Thank you Andy, the Neeeeeeey has been working great. It has balanced my cells very well. And I did arrange the balance cables with zip ties haha, looked messy in the picture, was so excited to send the pic ASAP! Andy included a hand written letter, lovely and I'm touched. Thanks so much!!!!
Thanks for the shout out, Andy! Yes, I know, a blog... ;) I'm just not very good at putting things in video format, or being in front of a camera. Edit: and yes, the balance leads are organized, that picture was work in progress :)
I'd like to add that Up North and Personal is also very helpful in youtube comments. Both answering questions as well as trying to correct misinformation from a very small number of other commenters.
I think a blog is excellent value! Andy was making a joke, I think. Also, blogs being text, are much easier for search engines to index, so your likely to have more people find you, so long as they're using a search engine, not youtube to perform the search. 😆
Hi, everyone) Thank You Andy! I have chosen flexible busburs after watching this video! And I have got perfect connection with them with sanding and cleaning with alcohol. No worming up and low resistance (don't remember, maybe 0,002 mOms) My 8cell battery have 1,150 mOm resistance on terminals and nearly 2,120 mOms on negative terminal connection after 200A Chint DC braker and GBat 200 A DC melted fuse and after bms on positive. Looks very effective and durable.
Excellent review Andy. Busbar temperature and poor contact surface area heating are surely one of main concern areas that needs to be monitored. Very interesting results indeed. My experience is similar to your test results. The Aliexpress Flexible busbars also came out #1 as depending on the dimension, they come in 300A and 400A high current versions. You can actually get suppliers to make custom lengths as well, besides having a wide range to select from. The #2 is tin plated copper bars. Copper has a lot less internal resistance than Aluminium. Aluminium only has 61% conductivity of copper, so much thicker conductor must be used. The main issue with copper is that it can form oxide and this oxide does not conduct well. Issue is addressed if it is tin or chrome plated. 😊👍 If you get slightly longer Aliexpress flexible busbars then bend and incorporate a small U-shape profile, this would allow the busbar to flex length-wise as well. This is how i got them to fit in my setup 😉👌
Thank you very very much for this! After our chat, I was worried that the flexible might have been two small. This is a wonderful result and makes me feel a lot better. The Anderson connector I am using is rated to 175A, so your test is nearly maximum load. Just wonderful! ^_^
I have a 16s pack with the EVE 304ah cells and the busbars don't even get warm to the touch during normal usage, which is minimal current as my entire battery bank is 36kWh.
Just check yours after you install them for hot spots, mine came with busbars, but they were not going to work in my setup (96v battery bank) so i made my own from 1/2" copper tube i flattened in bench vise and i had absolutely no hot spots since the copper tube moulded when i torqued the copper nut since i used copper studs and copper nuts. I went the copper route, because i read somewhere that the LiFePO4 cells were copper with nickel coating on the terminals.
Aluminum is famous for heating up and remaining hot , I work with it daily even deburring on a soft wheel will get that type of metal super hot . I'd go with a good copper busbar everytime. Great video , I really appreciate it helped me think of a couple new ideas for me to tryout myself.
Great test, I think for a moving boat the flexible busbars make sense. But indeed measuring every connection for resistance and oxidation makes sense. Thanks Andy!
Thank you! As with previous tests I did, the aluminium busbars are a better conductor as the copper busbars due to the fact they have larger dimensions as the standard copper busbars. But the contact areas are a real problem. Tinned copper is definitely better.
@ Andy is there some reason you don't use a conductive paste? I do build up welding with a mig welder for hours at a time 22-24 v 220-240 amps if connections get hot I use a conductive paste (can't recall the name) of it but it contains graphite I pull the connection apart clean it apply the paste and the heat is gone.
Hi Andy, a tip for thermal imaging: on a shiny and/or metal surface you need a layer with a known or near 1 emission factor as the emission factors of the materials above are nearly unpredictable. I use a bit of black electrical tape for that puspose.
Very well said Andy. LFP is indeed very different than Li-ion when it comes to applying an appropriate charging strategy to prolong the battery life. I have been running full off grid solar now for past 8 months, relying on 16x SUNPOWER MAXEON-3 400W panels and 6x VICTRON 50/100 Smartsolar controllers connected to BMS and CERBO GX to manage the whole setup. For battery I am running 12x 120Ah LFP from ITECH. The main challenge is in winter trying to recoup full charge on limited hours of productive sunlight and poor rainy weather. Often there is only around 3 hours of good sun in winter to charge at higher current >150A. It is great that LFP can take in much higher charge current than Lead Acid batteries. I utilise DVCC on CERBO GX to set upper limit of 250A for charging current and 14.5v on charging voltage as well to protect the system. With 1440Ah battery capacity 250A is only 0.17C, which is well below the 1C LFP is capable of. Happy to report that with some tweaking on the solar panel placement, this setup has been working extremely well and managed to deal with consecutive poor weather days with lots of reserve left. The POC Poof-Of-Concept phase has indeed completed successfully in proving if it is possible to go 100% off grid solar with current battery and solar technology. I have since contacted Synergy the power company to disconnect my power and finalise my account. Keep up with the good work. Are you planning to scale up your solar system to start parallel run on semi-of grid setup?
Thanks a lot for sharing. That is very interesting and great to hear. I think it depends where you are on this planet to make it work and how much power you consume. I am currently upgrading my solar on the garage and have also looked around for other suitable locations especially during winter time to get more energy. With an EV, pool and electric hotwater, I need lots.
Hello Andy,I want to share my experience with busbars,after an year using my battery bank. A few days ago I also completed 30 busbars for my 32 cells and 600 amp battery bank.I approached the problem from the point of view of corrosion that can occur at the aluminum terminals of the cells.I used a 35 mmp conductor and at the ends I used ring terminals made by me from 2 mm thick sheet, the sheet which has one surface of aluminum and the other surface of copper.I soldered the 35 mmp copper conductor to the copper surface of the terminals.Thereby it will come into contact with the cell terminals only the aluminum surface of the terminals.Thus, at a length of 18 cm, we obtained a resistance of 0.15-0.16 mohms. Before this setup, I used the same type of cable, the same length, but at the ends I used copper ring terminals soldered.I was fine for almost a year, but after a year some problems appeared due to the oxide that appeared between the aluminum terminals of the cells and the copper ring terminals. I opted for the version with flexible busbars because the placement of the cells requires it and because the cells are fixed in a frame with 300 Kgf.
hi Andy. looks like those braided copper straps did very well. since you mentioned that they were a bit too short i started looking around and i think i found the seller on Allie you used, well if it is the same seller they offer custom length straps aswell if you order 100 or more. maybe if there is enough demand from the community you could resell them. the biggest advantage using these straps is that they conform to their mounting, if one batt is higher it can move to accommodate the position. there is a reason heavy industry uses these kinds of bonding straps.
If you use a lower wattage incandescent light bulb as a resistor, it will light up while the capacitors are charging and it will dim and go dark when they are full, which will prevent you from hooking up the cable prematurely.
Roger, The Power supply is 48~54V. The Incandescent filament will be obliterated, if Andy doesn’t have a 54V filament incandescent bulb, right? 22+22 Ohm (11 Ohm approx) @ 5W is good as shown.
I wondered about this. This is good to know. I imagine that using a bulb with a voltage/wattage rating a little higher than the system being charged would be key to not losing the bulb in the process as you all said.
@@westking7746 we used this trick with a 12v bulb to charge super capacitors in car audio systems back in the day. My 5 farad capacitor even came with a bulb to use. I added a light bulb fixture and 7.5W bulb to my system as a pre-charge resistor, and with my 12KW Growatt inverter it takes a solid 20 seconds for it to dim and go dark. I think something around 20W may be ideal.
@@chevrofreak LOL. OK. Yeah. I remember the light bulb with the capacitor deal. I never knew what they were for. My Dad usually installed stuff like that.
I got sucked into the whole (make your own better busbars) but I’ve never had a problem with the bb that come with the cells… work great straight out of the packet
@Andy what i do not understand is the outcome of your second measurement, the internal resistant of the busbar at 160A. For example the first busbar did 1,2mOhm and 7,2 mV. That is not possible with 160A. The voltagedrop with 1,2 mOhm must be 160 x 1,2mOhm = 192milivolt. This value gives a wattage loss from 30,7 watt in that single busbar. :) I think the measurement of the internal resisant isn't right. What are your thoughts? I trust the voltage mesurement more than the internal resistant measurement. If we calculate the other way around than we get R=U/i = 7,2mV/160A=45 microOhm.
I'm pretty sure that the tester supplies an AC voltage at a particular frequency for the resistance test. Notice it has multiple prongs on each probe. There is a DC voltage test performed with one prong in each probe, and the resistance test is performed with the other prong(s) in each probe. It's not just a passive measurement, like a multimeter. Possibly one could conclude this makes it unsuitable for testing a bus bar, which clearly isn't a "chemical battery" and therefore isn't affected by that AC test, or the connected cell(s) are affecting the test, either way...
You are right, the figures are against physics. There is the ohms law U=R*I, which is violated by these figures. @Andy, please measure the voltage drop with your voltmeter, as well.
Hi Andy, I have not read all the other comments, if someone has written this. These flexible "busbars" are normaly more used to connect an electrical kabinet with its door and also in kombination with high frequency topics. As I know high frequency current is flowing only / better on a surface. Because of that this connectors are made. All this tiny wires are giving a much bigger surface than a solid wire / busbar. (Don't kill me if I am wrong, but as I know this is, what the flexible connectors are for.)
Thank you for your test and video. After thinking about this for a while, I think the solid busbars are problematic. They rely on the battery terminals being in exactly the same plane. If there is any twist the solid busbars will have to bend to compensate. The Aluminum busbar would have the greatest problem in this area as it has to be thicker to maintain the same conductivity as copper. (this may be why the aluminum terminals had the greatest connectivity problems.) I like the braided busbar as it generates the least stress on the battery terminal. Cheers, Ken
Hi Andy Keep in mind that the battery terminal tops also form an oxide and should be removed as well. A twisting motion and scotch bright under your thumb for a few seconds is all it takes and won’t distort the flatness detrimentally. Use a can of dust off to blow out the holes because you don’t want grit in there. I made a lapping tool that works great and fast for terminals that already have studs(I made a video).Wipe off the top with alcohol and put on your favorite anti oxidant compound within a few minutes. Preparing both contact surfaces makes a huge difference. The flexible braided buss is very good but there’s things you need to know. It is perhaps a bit short but it can be lengthened by squeezing it’s width in the middle with your fingers. The problem with those is they need periodic re torquing as the stands within the ferrule compress. This will eventually settle down or an embossing tool can be made that can pre compress (in a machine vice) and flatten the contact area. Interesting resistance readings you got.
@@babaluto I turned a blank perfectly flat and drilled a 6mm hole in it. The other end was drilled and taped 1/4-20 where I Loctite-d a socket head screw. I cut the “L” off a ball hex wrench so I could put it in a drill motor. The ball drill reduces any leaning and helps keep it flat on the terminal. I used a sheet of 400 wet&dry sand paper that I put thin double sided tape, cut to 1” squares and punched holes. Use a 6mm pin in the lapping tool to line up the sand paper. Low, low speed, light pressure about three rotations then a about one rotation in the one direction to release the fines in the paper so it doesn’t load up. The terminals must be absolutely free of oil or any oxide compound so I clean them before and after with alcohol. Any contamination will instantly load the paper in spots halting all progress. Soon after it’s lapped,use a very thin layer of an anti oxidant paste (Noalox) on the finished surface. Avoid getting the paste on the threads because it can increase the tension of the fastener when torquing.
@@SkypowerwithKarl Sounds very good. The tool I still have, I think I bought it from buggies unlimited, it is a hexagonal tool steel section with cutting edges milled into the facing side. A hole in the middle for the post. It fits nicely into a 7/8" socket for either an impact or drill driver. The cutting edges leave the surface super clean and flat. Haven't had any issues with it clogging or marring of the surface. I checked recently and Buggies doesn't list it any longer and I cannot find it anywhere else. I simply do not understand why someone would work so hard to make the bus bars so flat without checking the mating surface as well. Good stuff. Cheers!
From what others said, the terminals are made from some different aluminium than the bus bars and don't oxide very much. In this test, I did not clean or treat the terminals at all. And the tinned copper bars are fine with this.
@@OffGridGarageAustralia I’m sure they are a different alloy than the buss bars. The important difference is they have been machined. The buss bars have what you discovered is a rolled finish that have a tough low conductive, oxide skin. All aluminum oxides but it’ll take quite a while in a nice environment to be as bad as the finish of the stock plate. The terminals are pretty soft yet weldable so I’d guess a 5XXX alloy. The buss bars are probably one of three 2024, 6061 or 7075 . Probably 6061 because it’s the most common and cheaper than the high strength 7075. Glad you figured out the hot bars.
Good job on the presentation. I believe that I make an idea as to why your connectors on the hookup wire are a bit hot. When making a bench spot welder, I had a problem with my cable getting hotter than the welding point. We found that the connectors cross section area were smaller than the welding point. We made the connectors thicker. When we did this, the temperature at the connectors was much lower and the welding point started welding properly. Think about the wire size for your current flow. The wire and connectors are resistors in the circuit. Smaller (cross sectional area of the wire) wire, in this case, smaller connectors bigger resistor. I find that many do not take the connector size into account when building a circuit. I hope this helps. Fairwinds and following seas.
I think bending the flexible bus bar loosened the braid which shortened the length. I’m curious if it would have fit beforehand. Try putting a screwdriver through each hole and pull to try to lengthen it.
@@TheDigitalMermaid I’m saying stretch it back to its original length I’m thinking that’s it’s shorter than it’s factory center to center length because he was bending it back and forth and it didn’t appear to be missing the stud by much. And great video on the cerbo gx and display you explained exactly what I was confused about so I ordered one now lol
032822/2107h PST 🇺🇸. Danke Herr Andy. Understood the importance of transfer of power and the torque standards. I’m highly impressed with the flexible bar, because , even though it had 5 joints at each sides( the flat plate compressed to Cu braid and the Al battery threads, SS grub bolt, and the knurled SS nut) on one terminal; it ( flexible BB) surprisingly stayed cool. I’m not surprised at Madam Matty’s ( sorry if I misspelled the name) 2 cable bus bars, that stayed cool, because they both are AWG4. (4X10AWG=4 AWG) But, No comments on Al BB because it was a gift.😬 The normal Sn plated Cu bus bar, tested at China Labs and found suitable for the occasion, so it stayed cool. If you are asking my opinion, I’d say, stay with flat pure Cu bar 3~4mm X 20mm drilled elongated and smear MG Chemicals Carbon Conductive Grease #846-80g. The CCG will not harden and takes away all the joint (electrical) issues. Beware… the compound is messy messy and very messy. I have pronounced lewd verbal epithets while installing the same🤪. Do forgive if I exceeded my limits. Take care und 73s…
@@OffGridGarageAustralia I agree, and I think the idea with the #4 copper with lugs would be best with a small space between batteries. This would allow for any expansion and contraction so that there is no tension on the terminals as well. (Mermaid's dream cables)
Hey Andy, my hubby faithfully watches your videos. He said to tell you that as a retired mechanic when he had a bad connection he would use an internal/external star lock washer between the contact surfaces for 100% connection. Worked every time. Might try that between battery terminals and bus bars. He thinks it just might work
Hi Deb, thanks for your comment. That would be the worst connection for such high amperage. Imaging the star washer has only contact to either side where the stars are connecting to the metal surface. So all the current needs to go through these few connections points. This might be good for resistance but with amps going through it will heat up like crazy!
I'm not experienced with this issue but in other videos with thermal cameras I've seen a lot of discussion about measuring some surfaces and them not being able to get useful measurements with some materials. Usually it comes up that something extra is needed to get an accurate reading, which I think is perhaps applying a matte black thermally conductive tape to the surface and measuring that instead? Have you considered this sort of effect with thermal cameras? Of course it really doesn't matter in this case since you're using your hand anyway, just a side note. Edit: It looks like Fluke has a good simple guide on measuring reliably
Everything reflective cannot be measured with a thermal camera. It is like filming a mirror and you will only see the thermal reflections of yourself and your surroundings. Also, if you want to measure something behind a see through lid (or a window) than it is best practice to remove the lid when measuring. A good example is to try to film outside your home from behind a window. You only will see the thermal reflections of the inside of the room you are standing in.
Hi, some advice, I need to extend an equipotential bar, is it possible to join it with two 8 bolts instead of doing it all over again? or is it not recommended? Thank you
You understand, I presume, that your R, ΔV measurements are flawed, as they deviate from Ohm's law and test conditions. The series current is the same on all 5 jumpers, hence if you view them like shunts, the I = ΔV/R should have been the same, within meter's accuracy and rounding errors. They are in fact: 6.00, 14.12, 8.75, 8.50 and 6.25 Amps, very distant from the 160 Amps that were flawing during your test. Greetings from sunny Greece. Nikos
Maybe it is just me, but I'd call those things "interconnects". I think bus bars are different - in wiring up a battery a bus bar would be used when connecting the cells in parallel.
Yeah, OK, that makes actually sense as well. It's just another word. I used to work in switchboard manufacturing and we called them always a busbar if they are from solid copper material and not a cable.
Loving your channel and testing,just curious iam planning on building a parallal 4x100ah lithium set up in my caravan and want as best as possible ballance,would running equal length 70mm wire with both neg and b+ cables stacked to a single post then having a 70mm lead from that post going to the inverter be the best way? Also what effect on the voltage/current sharing when stacking 5 terminals onto one centre 250amp post,cheers.
copper for sure is good,,,, the tinned part is to prevent the galvanic corrosion between different metals,,, the tin coating decreases the conductivity a little
Great Video! I'm glad to see you really don't need to "upgrade" the busbars. I'm sure people need different types for different configurations, but for the most of us... Stick with standard copper!
To expand on what Andy said at the end; What is right depends entirely on each person's use and needs. For me, the effort to make the flexible was worth it because I'm using them in a high vibration, high shock loaded environment (on a boat, vibrations from a generator, and the crashing of waves). If your install is static, like Andy's, I think the bus bars that come with the batteries are just fine.
@@TheDigitalMermaid I think your design is a winner in an environment where movement is a possibility, your connections are much safer as there is far less exposed conductive parts improving safety, would be good to have covers over the studs as well like the type you get on car alternator terminals and i think it would be as safe as is possible, nice job
Andy, great video as always. I know it's impossible to do it as you put so much effort Into the videos for our entertainment but wish there was more videos to watch back to back (without restarting from the beginning) My new born son is finally out of icu and home, Logan will fall asleep many times in his life hearing uncle Andy do his thing 😋😃 In a country where we have load shedding frequently (south Africa can't supply enough power due to lack of maintenance to power stations ) solar is the way to go.
Very interesting video, thank you Andy! Aluminium needs plating or tinning to prevent oxide layer forming. If alu busbar was already plated then sanding would make it worse. Don't know how effective anti-ox paste is but I wouldn't trust it by itself.
there is a youtube guy "ray builds cool stuff" who tests the resistance via different methods of connecting the nickel plated copper busbars to his EVE 280Ah cells.... he (Ray) also noted one vendor sent him tinned brass busbars which increased the resistance a lot.....copper is the best choice and the thicker it is the higher its ampacity will be and the corresponding resistance... I recommend tinned copper bus bars and pure copper cables with tinned lugs that have adhesive shrink wrap at the lug/cable junction to limit oxidation... avoid brass bus bars...have a great day all....cheers from the off-grid farm in South Dakota.....USA
Thanks Michael. The aluminium busbars have actually a lower resistance than the standard copper ones coming with the cells. But obviously they have their problems with with oxidation and high resistance to the busbar if untreated. I agree, copper is definitely the way to go. Madi has actually used these adhesive heat shrink with her cables she made. I can see the clear glue coming out a bit where the heat shrink ends.
So, having always seen the options in your videos for BMS having separate resistance values for balancing, does this provide any real world advantage in speed of top balancing your battery bank's? Or is it just simpler to rely on equal length balance lead lengths and connection methods and let the BMS auto distribute the current? I still can't fathom why the options are in there for individual resistance values.... Thanks again for all your learning and sharing Andy!
Thanks Zoe. Different lengths of balance cables don't play a role as such. When the BMS measures voltages, there is pretty much no current flowing, therefore no voltage drop. I think the JK-BMS just measures the resistance of the balance cables. I'm not 100% sure either why it may be important though unless you have a real bad connection and it has trouble pushing these 2A through such a cable.
@@OffGridGarageAustralia thanks Andy! Does this mean the issues with your V1 battery bank coupled with the QUCC BMS having such a high millivolt deviation is due to not having balancing while charging activated in the app settings or actually the cells individual behaviour? Happy spat hour to you :)
A great test, thank you. Very different that I had expected. Aluminium should be as good as copper when there is double the area and the awg 4/0 cable is 3x the area of the original busbar, so how on earth could it be worse?!? The answer must be connections to the posts and perhaps crimps. Tin is a very soft metal. Although there isn't much of it on a tinned busbar it must be improving the surface contact somehow in a way aluminium doesn't. Likewise for the crimp ends of the wires.
I want to start experimenting for a new off grid house. But this video just again proofs: if you are going to do high current in any way, a good IR cam is a necessity. So that's probably the first thing I will investigate. But I'd rather have a good usb/phone version, because I can install a usb/phone version later on a PI to watch the installation.
Hi Andy great video as always, in regard to the busbars I have to say thay I had a problem we the alluminium, ones and to solve the problem I changed it with the pure copper semiflexible ones; the problem with the busbars is caused even by charging/discharging the battery at high currents.
Thank you Andy for doing this video. I was just about to make some fixable bus bars. But notice how both the fixable bus bar and the aluminum bar on the ends were cool. what would happen if you changed them and put them in the center and the other bars on the end. It seems that most of the heat is coming from battery post to battery post. 🤔
You make a case for certainly using the convenience of the standard busbar for initial top balancing. Maybe the final build can be a more painstaking exercise, but if several banks are to be assembled, a set of the standard busbars is warranted for top balancing in the background during the build.
Not sure if you have seen my previous videos but I have one battery bank already assembled with the aluminium bus bars for quite some time now (OK a few weeks only) and haven't had any issues after sanding and applying this paste to the contacts. The next two banks will be done with the standard bus bars coming with the cells, one bank will get the paste as well, the other won't. Just to see the difference over time.
I remember that GMC pickups from the 1940s, 1950s, and 1960s with both 6- and 12-volt systems quite often used the braided straps as ground straps between the body and the frame. Braided straps were also used between the battery and either the engine or a point on the frame. The only downside that I could see was that they were corrosion prone at the lead-acid battery negative terminals. The old 6-volt systems had positive battery cables as thick as a grown man's thumb, but I can't remember what the gauge was. My Dad used to make replacements for the corroded ground straps from scratch with a special crimper and terminal ends and soldered the terminal ends as insurance. The positive battery cable ends were replaced with a clamp on terminal end after cutting the corroded one off and stripping the insulation. They seemed to work OK at best. Those old battery systems were never that reliable even when new, especially the 6-volt outfits.
Does anyone know, where can I find precise information about the value of the torque for tightening busbar nuts? Thanks. You mentioned 4Nm. I guess it's M6 stud?
23:50 From the voltage across and resistance of each busbar that you measured, we can calculate the current through each busbar. Why is the current through each busbar not equal to each other?
@@OffGridGarageAustralia being a big bike build I went for the 24s to get a high voltage but didn't realise there's no serial port on it so I can't pull the data off to the bikes main diy LCD screen, I'm looking at trying to connect an Arduino to it via Bluetooth just so I can display amps and volts alongside bike mph
Hi, If I'm not mistaken when you connect in series you battery AH stays the same as a single cell. So it would make it a 300+ AH 12v bettery. Os this correct?
Hi Mike, if you torque them too high you can strip the terminal thread. I did this with at least one of my batteries. I'll show how to repair it soon. 4Nm is enough for these connections.
Here is actual resistance and power loss on the bus bars tested in this video: EVE Orig R=0.045mOhm Ploss=1.152W SuperAlu R=0.15mOhm Ploss=3.84W 4x10AWG Flex. R=0.0875mOhm Ploss=2.24W 1x4AWG Flex. R=0.106mOhm Ploss=2.72W Ali 'Flex' R=0.031mOhm Ploss=0.8W Calculated base on measured voltage drop with 160A of current. Ideally it would be best to measure on the battery terminals with high input impendance multimeter because bolts are carrying a little bit of current too and measurement would not be true. Kind of. As for thermography - it is a good idea to use black sharpie on your shiny metal parts...
Thanks for doing this additional maths and sharing it here. The overall test was more to show that the problem is with the connection and not so much with the actual material of the busbars people choose.
Great video Andy, I am curious how my DIY busbars would test out in your testing environment. I made mine from 1/2" (12.7mm) copper tube that i flattened in bench vice and punched holes that i made from a 10ft section i bought from hardware store for $13USD. Your braided test results has me intrigued as i wish more flexibility in my busbars and i just went and picked up a small section of copper braid wire that they commonly call "grounding braid wire" here in the USA for $2.74/ft and going to use copper tube as ferules on the ends. I previously plasti-dipped the copper tube diy busbars for insulation, so i am unsure if i should insulate them or not, it seemed them being bare was cooling the busbar combared to the insulated wire busbars.
insulating them does cause them to retain heat a bit....no longer has the natural radiator effect to get rid of the heat as the electricity flows through them...
Hola Andy he visto muchos videos y en casi todos los paquetes de barerias para EV utilizan barras colectoras de aluminio, eso si estas estan soldadas por láser entonces??
Hello I was trying to find where I can get a busbar similar to the first one for a different project. If you could point me to the right direction it will be greatly appreciated. Thanks
Andy, measuring the voltage drop and resistance of the bus bars from the stainless steel grub screw is erroneous. To get a true measurement of the connection, voltage drop and resistance the measurement needs to be taken directly from the battery terminals. That way the resistance of both the connection of the bus bar to the terminals and the bus bar itself are measured, which is what is important.
As Andy has said in many replies over a number of his videos, once the bus bars are on, he no longer has access to the actual terminal. They are completely covered by the bars. So he has the terminal screw, or the bar itself, that's it. And I see he in fact measured from both of these options in this video, albeit in different tests.
Not being able to access the battery terminal does not change the reality of the correct way to measure the bus bar connection, voltage drop and resistance.
All i am saying is that when measuring it is important to know what you are actually measuring. In the video Andy is not measuring what he thinks he is measuring, while it may be close. To get a correct measurement of the bus bars it has to be done from the battery terminals.
Great demonstration Andy, The Aluminium problems are likely due to the type of Aluminium, if it was 6xxx type Aluminium it's not suited for this purpose, 8xxx series was developed in the 1970's when copper was expensive and Aluminium was becoming popular for electrical use, other types of Aluminium had higher electrical resistance leading to excessive heat and fires, 8xxx Aluminium was developed and is the only type of Aluminium permitted under electrical code standards, IMO stick with the ones that come with the battery the supplier generally knows what works best based on their testing, the Ali braided type is also very good because it will dissipate heat very quickly, Easy fix is to drill a 1mm larger hole, also you mentioned to sand the burred edge, this is not recommended as you will sand into the plating of the copper, it's best to use a deburring tool or a good quality countersink bit to remove the burr.
Most people don't understand about resistance, not just the wire size, but the strands, "electrons travel on the outside of the wire or bar" so if you use welding, welders cable, a 4 gauge welders cable, "picking random numbers" might have 50 wires, where as a house wiring 4 gauge wire would only have 25 wires... hope this makes sense....
That's real interesting about the braided bus bar, anyone know how difficult they would be to make? I found suppliers that are copper braid suppliers, such as Arcor Electronics, and have them in rolls up to 1000' in flat or tubular designs in many cross section profiles.
Thank you. You would need the right end-caps made from tinned copper and the tools to crimp them. I think Up North and Personal made his own... somehow...
@@OffGridGarageAustralia Yes, I make my own. End caps are just pieces of (annealed) copper tube, compressed with a small hydraulic press (a manual one, around 10 tons should do). I nickel plate them using a nickel acetate solution (made with vinegar, a power supply and some pieces of nickel).
Struggling with bus bars for my LTO build, but to the topic... The bus bars you link for the flexible bus bars are 3mm thick and 20mm wide. I am lead to believe that the bus bar calc for copper is 1.2 x thickness (mm) x width (mm) which makes them capable of taking 72amps, which seems much lower than what you were testing. Did you have a calc that you use to determine suitability?
Thanks. I googled a few bus bar calculators and rating tables. They seem to give out different results du to different material for 'copper' and 'aluminium'. It also depends how the bus bar is installed, similar to cables. These flexible bus bars are also multilayer which affects the current capability as well. The ones coming with the cells are certainly not rated for 300A either but doing great and heating up at all.
@@OffGridGarageAustralia Thanks! When I look at nickle strips for 18650s, I get totally different results as well. Could you advise the measurements of the bus bars you are currently (pun!) using? I think I saw you draw 300amp without them heating?
@@GTrainRx7 sure. The normal bus bars which came with the cells are 20mm x 2mm and made of tinned copper. The aluminium bus bars are 20mm x 4mm and the flexible bus bar I showed is 20mm x 4mm braided tinned copper.
@@OffGridGarageAustralia Thanks! I think a more reasonable calculation is 20x2x (5) = 200amps, which matches better with the nickle strips and what you have demonstrated. I think the bars I have are good for 100 amps (20x1x5). I will only be drawing that for a few seconds, then less than 10 amps, so even if they do heat up momentarily, it should not be a problem. Also, thanks for inspiring me to do more with getting back into my battery gear :D
I picked aims over a renogy inverter based on reviews. Ren seemed to have reports of complete failure of the boards in as little as 3 uses. Many failed before 2 years if they can be believed. I think aims has lower standby consumption too. I consider it important.
Is better to have one 12S lifepo4 battery(one bms) but one busbar will be 1 meter long. Or 3pcs 4S lifepo4 batteries and 3psc bms (one on each 4S) in series of course? Space and place are limitations.
loose connections generate heat and can become a fire hazard so it is important to torque them to the manufactures specifications and periodically check them as you would when you do maintenance on a car's battery....
Andy - was this a fair test? Didn’t the first and last bus bar not have a heat source on one side of them? Can you repeat the test and move the same bus bars around to put a heat source on both sides of every bus bar
THey didn't have an aluminium busbar connected but just the cables to the inverter torqued with the same 4Nm. I can repeat the test with a 16s pack in the future so we have more opportunities to test different materials the same way.
By copper strip, do you mean a pure copper bar, like the supplied (by EVE or whoever) bus bars, but not "tinned"? A pure copper bar would be the best (affordable) bar, but it oxidises, so standard practice is to "tin" it. Usually nickel plating. A pure gold or silver bar would be better, but unless you're an oil magnate, who's going to do that. Imagine, an oil magnate building a DIY clean energy system with gold bus bars. 🤣
Hey Mark. If your strip is 12 mm wide 3 mm thick, 36 square mm section, and we follow the rule of 1 square mm per 5 Ampères, it could be good up to 180 Ampères. Cheers.
Hi Collin. Copper is a better conductor than gold, just gold doesn’t oxydise. In Ohm x meter x 10^9 at 300K or 26,85c° Silver 16 Copper 17 Gold 22 Aluminium 28 Zinc 61 Brass 71 Nickel 87 Iron 100 Platinum 111 Tin 120 Lead 208 ;-)
hi andy, is it possible for you to do a test for the JK BMS for something like 150a~200a continuous charge/discharge test, and check the temperature of the BMS and BMS''s cabling. I was fed-up with JBD/QUCC 200a BMS and looking for alternative BMS. Thank you.
They are cheaper for a reason. Far less material. Copper cannot be replaced except by more copper. It depends on your overall current you are planning to run though your cells. The PCB bars are great for smaller projects but if can get 200A from your battery, I would not risk it.
marine grade tinned copper cables are made to resist the salt-water corrosion but they are less conductive than pure copper cables...depends on where you are placing your battery setup... are you on a boat in the salt water?? or inland in a stationary build...???
I used 3/8 copper pipe squished flat. When using a thermal camera i recommend painting a strip of flat black paint on them so you can get the accurate temp and not reflections
A comment to the charging resistor. I also use anti spark resistors. Around 10 Ohm. Make sure to disconnect the resistor, when the big connection is made. For that i have installed a little fuse with a switch on the positive terminal. After the switch is the resistor soldered into flexible wire. At the end i use an alligator clip for busbars or a short solid wire for breakers. With that i have one to both hands free to make the connection and have no time pressure before the capacitors in the inverter discharged again. With this method i have absolutly no sparks. I don't like these battery resistance meters. Because many measure with AC. The result is useless, because batteries are used with DC. This measuring method is better for capacitors, where the frequency is important. For batteries i always use a dump load and measure the voltage drop.
Hi Andy, Greetings from the USA. A suggestion on the Buss wire and bar test connections. Switch the different test buss components to different cells and repeat your test. It's quite possible that the heat is actually coming from an internal cell connection. You may have hot cell terminals heating the buss material through thermal conduction. I realize that the aluminum is heating from the current it's carrying but if you have hot terminals you need to ensure it's due to an external connection rather than an internal one. Marking your hot cell terminals and the putting your cold buss links on that cell will tell you whether you have a bad terminal, bad terminal connection, or undersized buss conductor.
Makes sense. If the busbar itself is the issue then there should be a gradual change in temperaue from the hotspot to the "not so hot" spot. And not a sudden change with a visible separate temperature zone. My guess is also the cell underneath the busbar is radiating heat to the bar.
Hi Andy, I wonder if the aluminum buss bars would work better if you removed the oxidation layer from both sides of the buss bars, and also did a light sanding on the aluminum on the battery themselves -- and of course liberally used the anti-oxidation goop everywhere you sanded. I'd also be interested in seeing if using a brass or bronze stud and nuts would be better than the steel ones, as the brass or bronze should also conduct better. I would be interesting to see a re-test with those changes.... Philip
Hi. Everyone is using nickel plated copper as busbars for cells with aluminium terminals. So it should be ok, even though nickel and aluminium are not 'friends' in terms of galvanic corrosion? Much less than aluminium and copper itself though.
Those ally bars could do with some surface grinding! Fantastic test, it seems that heat or not tells you how good/ bad the bus bars are. If one does not have the camera. Thanks again for your effort.
Thanks Jackie. The aluminium bars will definitely work but need some treatment, sanding and no-ox-id paste. I'm just not sure how long this treated connection will last.
IME of automotive and marine electronics, 90% of issues are the connections, usually solder joints cracking followed by contact points needing a good sand down and re seat or replacing connection terminals Surprisingly (not to me) crimp joints are by far the least problematic area of an electrical system 👍
Thank you. That's exactly what I found too. The IR camera doe s a great job revealing these weak points in your system quickly. The crimp connection of this cable leading to the inverter seems to have a problem and gets really hot. I removed the heat shrink but could not really see a problem. I may just re-crimp it...
Hi, Andy, have you also tested stainless steel 304 nuts or serrated stainless steel 304 nuts would change the resistance of the same bus bars with same torque, would different nuts affect the current flow of the bus bars and results of your BMS? How about adding a layer of aluminum foil under bus bars or above bus bars to reduce resistance? I am going to use nickel plated bus bars with serrated stainless steel 304 on batteries in series, then apply dielectric grease to prevent corrosion and arching but now I would consider to use graphite grease to reduce resistance and corrosion without attracting dust. I am going to get a clamp meter as my multimeter would not test current other than 1.5V and 9V batteries. I figure this might be related to contact resistance and I am sure that different torque would even change voltage and current.
Not a problem if a busbar acts like a spring,one is supposed to compress the cells anyways, woven busbars can change in length too like your underpants even if I use neighter of them.
@@OffGridGarageAustralia hope so ;) Mind you, this is a non-stationary solution, so I figured using flexible, given the vibrations, would be better anyway.
The question now is, why do you use those aluminum bus bars for your build? They seem to have perpetual problems. I drilled and tapped (for the sense leads) the nickel plated copper bus bars that came with my EVE LF304 cells. I was worried about them only being 2mm thick and copper, but there seems to be enough threads for a sufficient connection.
Hi Andy, great test, thank you! This confirmed my gut feel that the original bus bars are fine. About the flexi-Ali bus bars "don't fit" I think that applies only for your huge batteries, for the "normal" sized ones they probably would be fine. Right?
The original busbars are actually pretty good considering they are 'free'. No, that does not matter which cells you use. The EVE LF280/LF304 have the same terminal distance. I've got some new ones now which have the welded stud and they have different distances between the termerminals.
@@OffGridGarageAustralia I was referring to the 176Ah (which I use) or even lower - the "poor people" choice 😉, they are definity slimmer. SRY for not mention it before.
What is the heat reating of the wires ? Generaly is 70 c to get more then 30 40 is not good at all .the onley solution is biger wires.also you need an adapter in order to connect aluminyum to coper .
It does not say anything on the wires. These are the ones which came with the Renogy inverter. I have to check the crimping as this seems to be the issue.
Thank you Andy, the Neeeeeeey has been working great. It has balanced my cells very well. And I did arrange the balance cables with zip ties haha, looked messy in the picture, was so excited to send the pic ASAP! Andy included a hand written letter, lovely and I'm touched. Thanks so much!!!!
Seems I am not the only one to get caught with AliExpress junk batteries, oh well good luck and I hope you get somewhere near your moneys worth.
Thanks Dennis. Great to have you on board and I could help to make your battery a bit better.
Dennis, look for MDS enterprise in Imphal, have have good EVE LF105s.
Thanks for the shout out, Andy! Yes, I know, a blog... ;) I'm just not very good at putting things in video format, or being in front of a camera.
Edit: and yes, the balance leads are organized, that picture was work in progress :)
I'd like to add that Up North and Personal is also very helpful in youtube comments. Both answering questions as well as trying to correct misinformation from a very small number of other commenters.
Do as i do, stay behind the camera 😁
I'm sure you have something to add to the community judging by your posts on here 😎👍
I think a blog is excellent value! Andy was making a joke, I think. Also, blogs being text, are much easier for search engines to index, so your likely to have more people find you, so long as they're using a search engine, not youtube to perform the search. 😆
@@Dirt-Diggler I do have some videos on my channel where I do that. I'll see if I can expand on that.
Appreciate your effort on documenting the entire thing
Hi, everyone)
Thank You Andy!
I have chosen flexible busburs after watching this video! And I have got perfect connection with them with sanding and cleaning with alcohol. No worming up and low resistance (don't remember, maybe 0,002 mOms) My 8cell battery have 1,150 mOm resistance on terminals and nearly 2,120 mOms on negative terminal connection after 200A Chint DC braker and GBat 200 A DC melted fuse and after bms on positive. Looks very effective and durable.
Thanks
Still waiting for my 8 280 cells , but i have learned so much on your channel.
Thanx a million amps!
Excellent review Andy. Busbar temperature and poor contact surface area heating are surely one of main concern areas that needs to be monitored. Very interesting results indeed. My experience is similar to your test results. The Aliexpress Flexible busbars also came out #1 as depending on the dimension, they come in 300A and 400A high current versions. You can actually get suppliers to make custom lengths as well, besides having a wide range to select from. The #2 is tin plated copper bars. Copper has a lot less internal resistance than Aluminium. Aluminium only has 61% conductivity of copper, so much thicker conductor must be used. The main issue with copper is that it can form oxide and this oxide does not conduct well. Issue is addressed if it is tin or chrome plated. 😊👍
If you get slightly longer Aliexpress flexible busbars then bend and incorporate a small U-shape profile, this would allow the busbar to flex length-wise as well. This is how i got them to fit in my setup 😉👌
Thank you Andy.
What a result.
Simply using the original that came with the cells is the best choice.
;-)
Yeah, I'm only using the ones coming with the cells now and it all works fine.
Thank you very very much for this! After our chat, I was worried that the flexible might have been two small. This is a wonderful result and makes me feel a lot better. The Anderson connector I am using is rated to 175A, so your test is nearly maximum load. Just wonderful! ^_^
Great job on those bus bars! :)
Yes, I can only say, congratulations on these bus bars and design. The quality seems to be perfect. Just don't put a washer underneath ;)
Soon as I saw you even torque the bolts, I knew you wasn't messing around, you're hard core testing this
Thank you!
Really enjoyed your experiment with busbars!
Perfect timing!! I was going to make some fancy aluminum bus bars from stock, but now I will just use the ones that came will the EVE 304 cells
I have a 16s pack with the EVE 304ah cells and the busbars don't even get warm to the touch during normal usage, which is minimal current as my entire battery bank is 36kWh.
Just check yours after you install them for hot spots, mine came with busbars, but they were not going to work in my setup (96v battery bank) so i made my own from 1/2" copper tube i flattened in bench vise and i had absolutely no hot spots since the copper tube moulded when i torqued the copper nut since i used copper studs and copper nuts. I went the copper route, because i read somewhere that the LiFePO4 cells were copper with nickel coating on the terminals.
@@williamhustonrn6160 terminals are made of aluminum....copper is a far superior conductor for busbars. or copper cables...
@@williamhustonrn6160 That is what I have used in the past. What wall thickness are you using? K, L or M
Aluminum is famous for heating up and remaining hot , I work with it daily even deburring on a soft wheel will get that type of metal super hot . I'd go with a good copper busbar everytime. Great video , I really appreciate it helped me think of a couple new ideas for me to tryout myself.
I was cutting drilling and shaping copper bus yesterday and they were almost burning me.
Great test, I think for a moving boat the flexible busbars make sense. But indeed measuring every connection for resistance and oxidation makes sense. Thanks Andy!
That's where the Flir camera comes into play. Very easy to see where the problem is...
Andy, I have totally switched everything to shrink tubing and zip ties for looms, connections and everything else. No more tape or wire messes for me!
Thanks for the video! I
In my experience aluminum is not a desirable conductor so your results make sense to me. 👍
Thank you! As with previous tests I did, the aluminium busbars are a better conductor as the copper busbars due to the fact they have larger dimensions as the standard copper busbars. But the contact areas are a real problem. Tinned copper is definitely better.
@ Andy is there some reason you don't use a conductive paste? I do build up welding with a mig welder for hours at a time 22-24 v 220-240 amps if connections get hot I use a conductive paste (can't recall the name) of it but it contains graphite I pull the connection apart clean it apply the paste and the heat is gone.
Well, the test has shown, it's not necessary. Except the aluminium bus bar, all others staid cool.
Hi Andy, a tip for thermal imaging: on a shiny and/or metal surface you need a layer with a known or near 1 emission factor as the emission factors of the materials above are nearly unpredictable. I use a bit of black electrical tape for that puspose.
Very well said Andy. LFP is indeed very different than Li-ion when it comes to applying an appropriate charging strategy to prolong the battery life.
I have been running full off grid solar now for past 8 months, relying on 16x SUNPOWER MAXEON-3 400W panels and 6x VICTRON 50/100 Smartsolar controllers connected to BMS and CERBO GX to manage the whole setup.
For battery I am running 12x 120Ah LFP from ITECH. The main challenge is in winter trying to recoup full charge on limited hours of productive sunlight and poor rainy weather. Often there is only around 3 hours of good sun in winter to charge at higher current >150A. It is great that LFP can take in much higher charge current than Lead Acid batteries. I utilise DVCC on CERBO GX to set upper limit of 250A for charging current and 14.5v on charging voltage as well to protect the system. With 1440Ah battery capacity 250A is only 0.17C, which is well below the 1C LFP is capable of.
Happy to report that with some tweaking on the solar panel placement, this setup has been working extremely well and managed to deal with consecutive poor weather days with lots of reserve left. The POC Poof-Of-Concept phase has indeed completed successfully in proving if it is possible to go 100% off grid solar with current battery and solar technology. I have since contacted Synergy the power company to disconnect my power and finalise my account.
Keep up with the good work.
Are you planning to scale up your solar system to start parallel run on semi-of grid setup?
Thanks a lot for sharing. That is very interesting and great to hear. I think it depends where you are on this planet to make it work and how much power you consume.
I am currently upgrading my solar on the garage and have also looked around for other suitable locations especially during winter time to get more energy. With an EV, pool and electric hotwater, I need lots.
Hello Andy,I want to share my experience with busbars,after an year using my battery bank.
A few days ago I also completed 30 busbars for my 32 cells and 600 amp battery bank.I approached the problem from the point of view of corrosion that can occur at the aluminum terminals of the cells.I used a 35 mmp conductor and at the ends I used ring terminals made by me from 2 mm thick sheet, the sheet which has one surface of aluminum and the other surface of copper.I soldered the 35 mmp copper conductor to the copper surface of the terminals.Thereby it will come into contact with the cell terminals only the aluminum surface of the terminals.Thus, at a length of 18 cm, we obtained a resistance of 0.15-0.16 mohms.
Before this setup, I used the same type of cable, the same length, but at the ends I used copper ring terminals soldered.I was fine for almost a year, but after a year some problems appeared due to the oxide that appeared between the aluminum terminals of the cells and the copper ring terminals.
I opted for the version with flexible busbars because the placement of the cells requires it and because the cells are fixed in a frame with 300 Kgf.
Andy just 6:30 into the piece, these videos keep getting better and better, keep em coming, Enjoyment and Learning! ........ S.P.A.T. to ya!
Thank you so much for this testing!
hi Andy.
looks like those braided copper straps did very well.
since you mentioned that they were a bit too short i started looking around and i think i found the seller on Allie you used, well if it is the same seller they offer custom length straps aswell if you order 100 or more.
maybe if there is enough demand from the community you could resell them.
the biggest advantage using these straps is that they conform to their mounting, if one batt is higher it can move to accommodate the position.
there is a reason heavy industry uses these kinds of bonding straps.
I use them on my battery, but I make them myself. It's time consuming, but they've been running for two years now without issues.
@@upnorthandpersonal You ought to make a video of how to make them, I think many would be interested.
And I guess by pulling a little on them they would still extend by a mm or so. They don't look fully extended in the video
@@ForbiddTV I'll give it a try. I have to make a set anyway this spring/summer.
If you use a lower wattage incandescent light bulb as a resistor, it will light up while the capacitors are charging and it will dim and go dark when they are full, which will prevent you from hooking up the cable prematurely.
Roger, The Power supply is 48~54V. The Incandescent filament will be obliterated, if Andy doesn’t have a 54V filament incandescent bulb, right? 22+22 Ohm (11 Ohm approx) @ 5W is good as shown.
@@sreekumarUSA I meant a 120v bulb. I use them regularly. Andy will have 230v bulbs, so lower wattage will be best for him.
I wondered about this. This is good to know. I imagine that using a bulb with a voltage/wattage rating a little higher than the system being charged would be key to not losing the bulb in the process as you all said.
@@westking7746 we used this trick with a 12v bulb to charge super capacitors in car audio systems back in the day. My 5 farad capacitor even came with a bulb to use.
I added a light bulb fixture and 7.5W bulb to my system as a pre-charge resistor, and with my 12KW Growatt inverter it takes a solid 20 seconds for it to dim and go dark. I think something around 20W may be ideal.
@@chevrofreak LOL. OK. Yeah. I remember the light bulb with the capacitor deal. I never knew what they were for. My Dad usually installed stuff like that.
I got sucked into the whole (make your own better busbars) but I’ve never had a problem with the bb that come with the cells… work great straight out of the packet
I'll use them for the new batteries going into the shelf soon as well.
@Andy what i do not understand is the outcome of your second measurement, the internal resistant of the busbar at 160A. For example the first busbar did 1,2mOhm and 7,2 mV. That is not possible with 160A. The voltagedrop with 1,2 mOhm must be 160 x 1,2mOhm = 192milivolt. This value gives a wattage loss from 30,7 watt in that single busbar. :)
I think the measurement of the internal resisant isn't right. What are your thoughts?
I trust the voltage mesurement more than the internal resistant measurement. If we calculate the other way around than we get R=U/i = 7,2mV/160A=45 microOhm.
things definitely don't add up.
I'm pretty sure that the tester supplies an AC voltage at a particular frequency for the resistance test. Notice it has multiple prongs on each probe. There is a DC voltage test performed with one prong in each probe, and the resistance test is performed with the other prong(s) in each probe.
It's not just a passive measurement, like a multimeter.
Possibly one could conclude this makes it unsuitable for testing a bus bar, which clearly isn't a "chemical battery" and therefore isn't affected by that AC test, or the connected cell(s) are affecting the test, either way...
Yes, 30,72W, that’s why the batteries get hot after longer use, but the battery would run less than 2hours under that load.
Cheers.
You are right, the figures are against physics. There is the ohms law U=R*I, which is violated by these figures.
@Andy, please measure the voltage drop with your voltmeter, as well.
Hi Andy, I have not read all the other comments, if someone has written this. These flexible "busbars" are normaly more used to connect an electrical kabinet with its door and also in kombination with high frequency topics.
As I know high frequency current is flowing only / better on a surface. Because of that this connectors are made. All this tiny wires are giving a much bigger surface than a solid wire / busbar.
(Don't kill me if I am wrong, but as I know this is, what the flexible connectors are for.)
Blogs are quicker to read than video
That is very interesting. Thankyou for the in-depth test.
Thank you.
Thank you for your test and video. After thinking about this for a while, I think the solid busbars are problematic. They rely on the battery terminals being in exactly the same plane. If there is any twist the solid busbars will have to bend to compensate. The Aluminum busbar would have the greatest problem in this area as it has to be thicker to maintain the same conductivity as copper. (this may be why the aluminum terminals had the greatest connectivity problems.) I like the braided busbar as it generates the least stress on the battery terminal. Cheers, Ken
Merci Andy pour encore une fois une belle démonstration technique. Bonne continuation.
Merci beaucoup!
I'm impressed by the original tin and copper busbars.
Hi Andy
Keep in mind that the battery terminal tops also form an oxide and should be removed as well. A twisting motion and scotch bright under your thumb for a few seconds is all it takes and won’t distort the flatness detrimentally. Use a can of dust off to blow out the holes because you don’t want grit in there. I made a lapping tool that works great and fast for terminals that already have studs(I made a video).Wipe off the top with alcohol and put on your favorite anti oxidant compound within a few minutes. Preparing both contact surfaces makes a huge difference.
The flexible braided buss is very good but there’s things you need to know. It is perhaps a bit short but it can be lengthened by squeezing it’s width in the middle with your fingers. The problem with those is they need periodic re torquing as the stands within the ferrule compress. This will eventually settle down or an embossing tool can be made that can pre compress (in a machine vice) and flatten the contact area. Interesting resistance readings you got.
From my lead acid days, I use a facing tool that slips over the threaded post that takes any slight crowns off of the post.
@@babaluto
I turned a blank perfectly flat and drilled a 6mm hole in it. The other end was drilled and taped 1/4-20 where I Loctite-d a socket head screw. I cut the “L” off a ball hex wrench so I could put it in a drill motor. The ball drill reduces any leaning and helps keep it flat on the terminal. I used a sheet of 400 wet&dry sand paper that I put thin double sided tape, cut to 1” squares and punched holes. Use a 6mm pin in the lapping tool to line up the sand paper. Low, low speed, light pressure about three rotations then a about one rotation in the one direction to release the fines in the paper so it doesn’t load up. The terminals must be absolutely free of oil or any oxide compound so I clean them before and after with alcohol. Any contamination will instantly load the paper in spots halting all progress. Soon after it’s lapped,use a very thin layer of an anti oxidant paste (Noalox) on the finished surface. Avoid getting the paste on the threads because it can increase the tension of the fastener when torquing.
@@SkypowerwithKarl Sounds very good. The tool I still have, I think I bought it from buggies unlimited, it is a hexagonal tool steel section with cutting edges milled into the facing side. A hole in the middle for the post. It fits nicely into a 7/8" socket for either an impact or drill driver. The cutting edges leave the surface super clean and flat. Haven't had any issues with it clogging or marring of the surface. I checked recently and Buggies doesn't list it any longer and I cannot find it anywhere else. I simply do not understand why someone would work so hard to make the bus bars so flat without checking the mating surface as well. Good stuff. Cheers!
From what others said, the terminals are made from some different aluminium than the bus bars and don't oxide very much. In this test, I did not clean or treat the terminals at all. And the tinned copper bars are fine with this.
@@OffGridGarageAustralia
I’m sure they are a different alloy than the buss bars. The important difference is they have been machined. The buss bars have what you discovered is a rolled finish that have a tough low conductive, oxide skin. All aluminum oxides but it’ll take quite a while in a nice environment to be as bad as the finish of the stock plate. The terminals are pretty soft yet weldable so I’d guess a 5XXX alloy. The buss bars are probably one of three 2024, 6061 or 7075 . Probably 6061 because it’s the most common and cheaper than the high strength 7075.
Glad you figured out the hot bars.
Good job on the presentation. I believe that I make an idea as to why your connectors on the hookup wire are a bit hot. When making a bench spot welder, I had a problem with my cable getting hotter than the welding point. We found that the connectors cross section area were smaller than the welding point. We made the connectors thicker. When we did this, the temperature at the connectors was much lower and the welding point started welding properly. Think about the wire size for your current flow. The wire and connectors are resistors in the circuit. Smaller (cross sectional area of the wire) wire, in this case, smaller connectors bigger resistor.
I find that many do not take the connector size into account when building a circuit.
I hope this helps. Fairwinds and following seas.
I think bending the flexible bus bar loosened the braid which shortened the length. I’m curious if it would have fit beforehand. Try putting a screwdriver through each hole and pull to try to lengthen it.
If you have to pull it that tight to connect it, is it really flexible anymore?
@@TheDigitalMermaid I’m saying stretch it back to its original length I’m thinking that’s it’s shorter than it’s factory center to center length because he was bending it back and forth and it didn’t appear to be missing the stud by much. And great video on the cerbo gx and display you explained exactly what I was confused about so I ordered one now lol
Do not try this. Because the braid ends may get , either detached or get lose , causing issues. Prepare a new one to exact measurement, instead.
032822/2107h PST 🇺🇸. Danke Herr Andy. Understood the importance of transfer of power and the torque standards. I’m highly impressed with the flexible bar, because , even though it had 5 joints at each sides( the flat plate compressed to Cu braid and the Al battery threads, SS grub bolt, and the knurled SS nut) on one terminal; it ( flexible BB) surprisingly stayed cool.
I’m not surprised at Madam Matty’s ( sorry if I misspelled the name) 2 cable bus bars, that stayed cool, because they both are AWG4. (4X10AWG=4 AWG) But, No comments on Al BB because it was a gift.😬
The normal Sn plated Cu bus bar, tested at China Labs and found suitable for the occasion, so it stayed cool.
If you are asking my opinion, I’d say, stay with flat pure Cu bar 3~4mm X 20mm drilled elongated and smear
MG Chemicals Carbon Conductive Grease #846-80g. The CCG will not harden and takes away all the joint (electrical) issues. Beware… the compound is messy messy and very messy. I have pronounced lewd verbal epithets while installing the same🤪. Do forgive if I exceeded my limits. Take care und 73s…
Nice to know. I charge at 30 amps and discharge at 50 max so i will just use the bus bars that came with my LF304 cells. Thanks OGG!
Yes, use the bars coming with the cells, they will be totally fine.
Nice results, thanks Andy.
The original Buzzbar is a god choise tinned Cooper works well together Whit Alu but it should be oxide free and vhit paste
Very interesting Andy. I used solid copper for my bank, but almost went with aluminum. Glad I didn't now! Awesome test as always! Thank you
Thanks Dan! 👍 Copper is the way to go, I think.
@@OffGridGarageAustralia I agree, and I think the idea with the #4 copper with lugs would be best with a small space between batteries. This would allow for any expansion and contraction so that there is no tension on the terminals as well. (Mermaid's dream cables)
Hey Andy, my hubby faithfully watches your videos. He said to tell you that as a retired mechanic when he had a bad connection he would use an internal/external star lock washer between the contact surfaces for 100% connection. Worked every time. Might try that between battery terminals and bus bars. He thinks it just might work
Hi Deb, thanks for your comment. That would be the worst connection for such high amperage. Imaging the star washer has only contact to either side where the stars are connecting to the metal surface. So all the current needs to go through these few connections points. This might be good for resistance but with amps going through it will heat up like crazy!
Agreed
to wat he was sayin at 2 min, the phones are giving us ADD. soon as i leave it in a different room blogs, articles n such are gold
I'm not experienced with this issue but in other videos with thermal cameras I've seen a lot of discussion about measuring some surfaces and them not being able to get useful measurements with some materials. Usually it comes up that something extra is needed to get an accurate reading, which I think is perhaps applying a matte black thermally conductive tape to the surface and measuring that instead? Have you considered this sort of effect with thermal cameras?
Of course it really doesn't matter in this case since you're using your hand anyway, just a side note.
Edit: It looks like Fluke has a good simple guide on measuring reliably
Everything reflective cannot be measured with a thermal camera. It is like filming a mirror and you will only see the thermal reflections of yourself and your surroundings.
Also, if you want to measure something behind a see through lid (or a window) than it is best practice to remove the lid when measuring.
A good example is to try to film outside your home from behind a window. You only will see the thermal reflections of the inside of the room you are standing in.
I have a thermal night vision setup and I can confirm this. A K type thermocouple may give more meaningful answers.
Hi, some advice, I need to extend an equipotential bar, is it possible to join it with two 8 bolts instead of doing it all over again? or is it not recommended? Thank you
You understand, I presume, that your R, ΔV measurements are flawed, as they deviate from Ohm's law and test conditions. The series current is the same on all 5 jumpers, hence if you view them like shunts, the I = ΔV/R should have been the same, within meter's accuracy and rounding errors. They are in fact: 6.00, 14.12, 8.75, 8.50 and 6.25 Amps, very distant from the 160 Amps that were flawing during your test. Greetings from sunny Greece. Nikos
Yes, I know that but just presenting the overall verdict, that not the material is the problem but the resistance.
Maybe it is just me, but I'd call those things "interconnects". I think bus bars are different - in wiring up a battery a bus bar would be used when connecting the cells in parallel.
Yeah, OK, that makes actually sense as well. It's just another word. I used to work in switchboard manufacturing and we called them always a busbar if they are from solid copper material and not a cable.
Loving your channel and testing,just curious iam planning on building a parallal 4x100ah lithium set up in my caravan and want as best as possible ballance,would running equal length 70mm wire with both neg and b+ cables stacked to a single post then having a 70mm lead from that post going to the inverter be the best way? Also what effect on the voltage/current sharing when stacking 5 terminals onto one centre 250amp post,cheers.
Thanks for this Video. Conclusion: High Power loves copper, even more tinned copper!
copper for sure is good,,,, the tinned part is to prevent the galvanic corrosion between different metals,,, the tin coating decreases the conductivity a little
The aluminium works as well if the connection is good 😉
Great Video! I'm glad to see you really don't need to "upgrade" the busbars. I'm sure people need different types for different configurations, but for the most of us... Stick with standard copper!
To expand on what Andy said at the end; What is right depends entirely on each person's use and needs. For me, the effort to make the flexible was worth it because I'm using them in a high vibration, high shock loaded environment (on a boat, vibrations from a generator, and the crashing of waves). If your install is static, like Andy's, I think the bus bars that come with the batteries are just fine.
@@TheDigitalMermaid I think your design is a winner in an environment where movement is a possibility, your connections are much safer as there is far less exposed conductive parts improving safety, would be good to have covers over the studs as well like the type you get on car alternator terminals and i think it would be as safe as is possible, nice job
Andy, great video as always. I know it's impossible to do it as you put so much effort Into the videos for our entertainment but wish there was more videos to watch back to back (without restarting from the beginning)
My new born son is finally out of icu and home, Logan will fall asleep many times in his life hearing uncle Andy do his thing 😋😃
In a country where we have load shedding frequently (south Africa can't supply enough power due to lack of maintenance to power stations ) solar is the way to go.
Very interesting video, thank you Andy! Aluminium needs plating or tinning to prevent oxide layer forming. If alu busbar was already plated then sanding would make it worse. Don't know how effective anti-ox paste is but I wouldn't trust it by itself.
there is a youtube guy "ray builds cool stuff" who tests the resistance via different methods of connecting the nickel plated copper busbars to his EVE 280Ah cells.... he (Ray) also noted one vendor sent him tinned brass busbars which increased the resistance a lot.....copper is the best choice and the thicker it is the higher its ampacity will be and the corresponding resistance... I recommend tinned copper bus bars and pure copper cables with tinned lugs that have adhesive shrink wrap at the lug/cable junction to limit oxidation...
avoid brass bus bars...have a great day all....cheers from the off-grid farm in South Dakota.....USA
Thanks Michael. The aluminium busbars have actually a lower resistance than the standard copper ones coming with the cells. But obviously they have their problems with with oxidation and high resistance to the busbar if untreated.
I agree, copper is definitely the way to go. Madi has actually used these adhesive heat shrink with her cables she made. I can see the clear glue coming out a bit where the heat shrink ends.
So, having always seen the options in your videos for BMS having separate resistance values for balancing, does this provide any real world advantage in speed of top balancing your battery bank's? Or is it just simpler to rely on equal length balance lead lengths and connection methods and let the BMS auto distribute the current? I still can't fathom why the options are in there for individual resistance values....
Thanks again for all your learning and sharing Andy!
Thanks Zoe. Different lengths of balance cables don't play a role as such. When the BMS measures voltages, there is pretty much no current flowing, therefore no voltage drop. I think the JK-BMS just measures the resistance of the balance cables. I'm not 100% sure either why it may be important though unless you have a real bad connection and it has trouble pushing these 2A through such a cable.
@@OffGridGarageAustralia thanks Andy!
Does this mean the issues with your V1 battery bank coupled with the QUCC BMS having such a high millivolt deviation is due to not having balancing while charging activated in the app settings or actually the cells individual behaviour?
Happy spat hour to you :)
Absolutely fascinating, thank you!
A great test, thank you. Very different that I had expected. Aluminium should be as good as copper when there is double the area and the awg 4/0 cable is 3x the area of the original busbar, so how on earth could it be worse?!? The answer must be connections to the posts and perhaps crimps. Tin is a very soft metal. Although there isn't much of it on a tinned busbar it must be improving the surface contact somehow in a way aluminium doesn't. Likewise for the crimp ends of the wires.
I want to start experimenting for a new off grid house. But this video just again proofs: if you are going to do high current in any way, a good IR cam is a necessity. So that's probably the first thing I will investigate. But I'd rather have a good usb/phone version, because I can install a usb/phone version later on a PI to watch the installation.
Hi Andy great video as always, in regard to the busbars I have to say thay I had a problem we the alluminium, ones and to solve the problem I changed it with the pure copper semiflexible ones; the problem with the busbars is caused even by charging/discharging the battery at high currents.
So, has the copper bus bar resolved the issue?
@@OffGridGarageAustralia Absolutely yes it solved the problem immediatly.
Thank you Andy for doing this video.
I was just about to make some fixable bus bars.
But notice how both the fixable bus bar and the aluminum bar on the ends were cool.
what would happen if you changed them and put them in the center and the other bars on the end.
It seems that most of the heat is coming from battery post to battery post. 🤔
Thanks Dennis. I haven't had time to do more testing but I will do another test with an 8s setup at some stage where we can test more materials.
You make a case for certainly using the convenience of the standard busbar for initial top balancing.
Maybe the final build can be a more painstaking exercise, but if several banks are to be assembled, a set of the standard busbars is warranted for top balancing in the background during the build.
Not sure if you have seen my previous videos but I have one battery bank already assembled with the aluminium bus bars for quite some time now (OK a few weeks only) and haven't had any issues after sanding and applying this paste to the contacts.
The next two banks will be done with the standard bus bars coming with the cells, one bank will get the paste as well, the other won't. Just to see the difference over time.
I remember that GMC pickups from the 1940s, 1950s, and 1960s with both 6- and 12-volt systems quite often used the braided straps as ground straps between the body and the frame. Braided straps were also used between the battery and either the engine or a point on the frame. The only downside that I could see was that they were corrosion prone at the lead-acid battery negative terminals. The old 6-volt systems had positive battery cables as thick as a grown man's thumb, but I can't remember what the gauge was.
My Dad used to make replacements for the corroded ground straps from scratch with a special crimper and terminal ends and soldered the terminal ends as insurance. The positive battery cable ends were replaced with a clamp on terminal end after cutting the corroded one off and stripping the insulation. They seemed to work OK at best. Those old battery systems were never that reliable even when new, especially the 6-volt outfits.
Does anyone know, where can I find precise information about the value of the torque for tightening busbar nuts? Thanks.
You mentioned 4Nm. I guess it's M6 stud?
23:50 From the voltage across and resistance of each busbar that you measured, we can calculate the current through each busbar.
Why is the current through each busbar not equal to each other?
just received my jk bms after seeing your 'reviews', i'm really happy with how its balanced the pack.
The JK-BMS is really great and works a treat.
@@OffGridGarageAustralia being a big bike build I went for the 24s to get a high voltage but didn't realise there's no serial port on it so I can't pull the data off to the bikes main diy LCD screen, I'm looking at trying to connect an Arduino to it via Bluetooth just so I can display amps and volts alongside bike mph
Hi, If I'm not mistaken when you connect in series you battery AH stays the same as a single cell. So it would make it a 300+ AH 12v bettery. Os this correct?
the link in the description for the Rnogy inverter is for the US one, just a heads up.
hello Andy, quick one what si the risk of over-torquing the bus bars9higher than 6Nm? in case, you don't have a torque wrench.
Hi Mike, if you torque them too high you can strip the terminal thread. I did this with at least one of my batteries. I'll show how to repair it soon.
4Nm is enough for these connections.
Here is actual resistance and power loss on the bus bars tested in this video:
EVE Orig R=0.045mOhm Ploss=1.152W
SuperAlu R=0.15mOhm Ploss=3.84W
4x10AWG Flex. R=0.0875mOhm Ploss=2.24W
1x4AWG Flex. R=0.106mOhm Ploss=2.72W
Ali 'Flex' R=0.031mOhm Ploss=0.8W
Calculated base on measured voltage drop with 160A of current.
Ideally it would be best to measure on the battery terminals with high input impendance multimeter because bolts are carrying a little bit of current too and measurement would not be true. Kind of.
As for thermography - it is a good idea to use black sharpie on your shiny metal parts...
now that is good information....thanks
Thanks for doing this additional maths and sharing it here.
The overall test was more to show that the problem is with the connection and not so much with the actual material of the busbars people choose.
Great video Andy, I am curious how my DIY busbars would test out in your testing environment. I made mine from 1/2" (12.7mm) copper tube that i flattened in bench vice and punched holes that i made from a 10ft section i bought from hardware store for $13USD. Your braided test results has me intrigued as i wish more flexibility in my busbars and i just went and picked up a small section of copper braid wire that they commonly call "grounding braid wire" here in the USA for $2.74/ft and going to use copper tube as ferules on the ends. I previously plasti-dipped the copper tube diy busbars for insulation, so i am unsure if i should insulate them or not, it seemed them being bare was cooling the busbar combared to the insulated wire busbars.
There are websites that sell flat or round copper braid profiles in many sizes by the roll.
insulating them does cause them to retain heat a bit....no longer has the natural radiator effect to get rid of the heat as the electricity flows through them...
Just to provide balance, I have bought 8 x Lifepo4 105ah cells from litokala and they capacity test and perform perfectly.
WOW you ARE lucky!
Great, thanks for sharing. Hope they have better quality now.
Did you know about the issues when you ordered them or found out later?
Hola Andy he visto muchos videos y en casi todos los paquetes de barerias para EV utilizan barras colectoras de aluminio, eso si estas estan soldadas por láser entonces??
Do you recommend solder and crimping the electric cables??
Hello I was trying to find where I can get a busbar similar to the first one for a different project. If you could point me to the right direction it will be greatly appreciated. Thanks
I made my bus bars out of 2/0 copper. It was welding cable.
Andy, measuring the voltage drop and resistance of the bus bars from the stainless steel grub screw is erroneous. To get a true measurement of the connection, voltage drop and resistance the measurement needs to be taken directly from the battery terminals. That way the resistance of both the connection of the bus bar to the terminals and the bus bar itself are measured, which is what is important.
As Andy has said in many replies over a number of his videos, once the bus bars are on, he no longer has access to the actual terminal. They are completely covered by the bars. So he has the terminal screw, or the bar itself, that's it. And I see he in fact measured from both of these options in this video, albeit in different tests.
Not being able to access the battery terminal does not change the reality of the correct way to measure the bus bar connection, voltage drop and resistance.
@@dan2304 Guess he has to become a magician then. Or are you saying he should just never perform these tests?
All i am saying is that when measuring it is important to know what you are actually measuring. In the video Andy is not measuring what he thinks he is measuring, while it may be close. To get a correct measurement of the bus bars it has to be done from the battery terminals.
@@dan2304 right. Thank you for explaining. 😊
Great demonstration Andy, The Aluminium problems are likely due to the type of Aluminium, if it was 6xxx type Aluminium it's not suited for this purpose, 8xxx series was developed in the 1970's when copper was expensive and Aluminium was becoming popular for electrical use, other types of Aluminium had higher electrical resistance leading to excessive heat and fires, 8xxx Aluminium was developed and is the only type of Aluminium permitted under electrical code standards, IMO stick with the ones that come with the battery the supplier generally knows what works best based on their testing, the Ali braided type is also very good because it will dissipate heat very quickly, Easy fix is to drill a 1mm larger hole, also you mentioned to sand the burred edge, this is not recommended as you will sand into the plating of the copper, it's best to use a deburring tool or a good quality countersink bit to remove the burr.
Most people don't understand about resistance, not just the wire size, but the strands, "electrons travel on the outside of the wire or bar" so if you use welding, welders cable, a 4 gauge welders cable, "picking random numbers" might have 50 wires, where as a house wiring 4 gauge wire would only have 25 wires... hope this makes sense....
Please Andy, I need two cell of this battery and balancer , how can i get it? Thank, am in Nigeria.
That's real interesting about the braided bus bar, anyone know how difficult they would be to make? I found suppliers that are copper braid suppliers, such as Arcor Electronics, and have them in rolls up to 1000' in flat or tubular designs in many cross section profiles.
Thank you. You would need the right end-caps made from tinned copper and the tools to crimp them. I think Up North and Personal made his own... somehow...
@@OffGridGarageAustralia Yes, I make my own. End caps are just pieces of (annealed) copper tube, compressed with a small hydraulic press (a manual one, around 10 tons should do). I nickel plate them using a nickel acetate solution (made with vinegar, a power supply and some pieces of nickel).
Struggling with bus bars for my LTO build, but to the topic... The bus bars you link for the flexible bus bars are 3mm thick and 20mm wide. I am lead to believe that the bus bar calc for copper is 1.2 x thickness (mm) x width (mm) which makes them capable of taking 72amps, which seems much lower than what you were testing. Did you have a calc that you use to determine suitability?
Thanks. I googled a few bus bar calculators and rating tables. They seem to give out different results du to different material for 'copper' and 'aluminium'. It also depends how the bus bar is installed, similar to cables. These flexible bus bars are also multilayer which affects the current capability as well.
The ones coming with the cells are certainly not rated for 300A either but doing great and heating up at all.
@@OffGridGarageAustralia Thanks! When I look at nickle strips for 18650s, I get totally different results as well. Could you advise the measurements of the bus bars you are currently (pun!) using? I think I saw you draw 300amp without them heating?
@@GTrainRx7 sure. The normal bus bars which came with the cells are 20mm x 2mm and made of tinned copper. The aluminium bus bars are 20mm x 4mm and the flexible bus bar I showed is 20mm x 4mm braided tinned copper.
@@OffGridGarageAustralia Thanks! I think a more reasonable calculation is 20x2x (5) = 200amps, which matches better with the nickle strips and what you have demonstrated. I think the bars I have are good for 100 amps (20x1x5). I will only be drawing that for a few seconds, then less than 10 amps, so even if they do heat up momentarily, it should not be a problem. Also, thanks for inspiring me to do more with getting back into my battery gear :D
@@GTrainRx7 great to hear. 100A for a few seconds will be totally fine, even with a smaller bus bar.
I picked aims over a renogy inverter based on reviews. Ren seemed to have reports of complete failure of the boards in as little as 3 uses. Many failed before 2 years if they can be believed. I think aims has lower standby consumption too. I consider it important.
Is better to have one 12S lifepo4 battery(one bms) but one busbar will be 1 meter long. Or 3pcs 4S lifepo4 batteries and 3psc bms (one on each 4S) in series of course? Space and place are limitations.
loose connections generate heat and can become a fire hazard so it is important to torque them to the manufactures specifications and periodically check them as you would when you do maintenance on a car's battery....
Yeah, if you have vibration, you should check...
Andy - was this a fair test? Didn’t the first and last bus bar not have a heat source on one side of them? Can you repeat the test and move the same bus bars around to put a heat source on both sides of every bus bar
THey didn't have an aluminium busbar connected but just the cables to the inverter torqued with the same 4Nm. I can repeat the test with a 16s pack in the future so we have more opportunities to test different materials the same way.
hi Andy, is 3mm copper strip no good for busbars/
By copper strip, do you mean a pure copper bar, like the supplied (by EVE or whoever) bus bars, but not "tinned"?
A pure copper bar would be the best (affordable) bar, but it oxidises, so standard practice is to "tin" it. Usually nickel plating. A pure gold or silver bar would be better, but unless you're an oil magnate, who's going to do that.
Imagine, an oil magnate building a DIY clean energy system with gold bus bars. 🤣
Hey Mark.
If your strip is 12 mm wide 3 mm thick, 36 square mm section, and we follow the rule of 1 square mm per 5 Ampères, it could be good up to 180 Ampères.
Cheers.
Hi Collin.
Copper is a better conductor than gold, just gold doesn’t oxydise.
In Ohm x meter x 10^9 at 300K or 26,85c°
Silver 16
Copper 17
Gold 22
Aluminium 28
Zinc 61
Brass 71
Nickel 87
Iron 100
Platinum 111
Tin 120
Lead 208
;-)
@@hommerdalor6301 I stand corrected. I should have said silver. Everyone else, substitute gold with silver in my comments above. There, fixed it. 😊
@@CollinBaillie Cool, so I checked metal resistivity again, and shared for our friends who don’t even know it exist.
:-)
hi andy, is it possible for you to do a test for the JK BMS for something like 150a~200a continuous charge/discharge test, and check the temperature of the BMS and BMS''s cabling. I was fed-up with JBD/QUCC 200a BMS and looking for alternative BMS. Thank you.
i set up is 16s 2p 200Ah LFP cells, my best busbars are 25mm² copper cable with SC25-8 copper lug and 3mm thick 1 inch wide copper plate.
@OffGridGarageAustralia whats your take on pcb busbars? Jehugarcia is selling them.
Pcb is probably cheap, but way less copper seems a bit risky?
They are cheaper for a reason. Far less material. Copper cannot be replaced except by more copper.
It depends on your overall current you are planning to run though your cells. The PCB bars are great for smaller projects but if can get 200A from your battery, I would not risk it.
marine grade tinned copper cables are made to resist the salt-water corrosion but they are less conductive than pure copper cables...depends on where you are placing your battery setup... are you on a boat in the salt water?? or inland in a stationary build...???
Just in the garage in South East Queensland 😉
I used 3/8 copper pipe squished flat.
When using a thermal camera i recommend painting a strip of flat black paint on them so you can get the accurate temp and not reflections
A comment to the charging resistor. I also use anti spark resistors. Around 10 Ohm. Make sure to disconnect the resistor, when the big connection is made. For that i have installed a little fuse with a switch on the positive terminal. After the switch is the resistor soldered into flexible wire. At the end i use an alligator clip for busbars or a short solid wire for breakers. With that i have one to both hands free to make the connection and have no time pressure before the capacitors in the inverter discharged again. With this method i have absolutly no sparks.
I don't like these battery resistance meters. Because many measure with AC. The result is useless, because batteries are used with DC. This measuring method is better for capacitors, where the frequency is important. For batteries i always use a dump load and measure the voltage drop.
Hi Andy, Greetings from the USA. A suggestion on the Buss wire and bar test connections. Switch the different test buss components to different cells and repeat your test. It's quite possible that the heat is actually coming from an internal cell connection. You may have hot cell terminals heating the buss material through thermal conduction. I realize that the aluminum is heating from the current it's carrying but if you have hot terminals you need to ensure it's due to an external connection rather than an internal one. Marking your hot cell terminals and the putting your cold buss links on that cell will tell you whether you have a bad terminal, bad terminal connection, or undersized buss conductor.
Makes sense. If the busbar itself is the issue then there should be a gradual change in temperaue from the hotspot to the "not so hot" spot. And not a sudden change with a visible separate temperature zone.
My guess is also the cell underneath the busbar is radiating heat to the bar.
Hi Andy,
I wonder if the aluminum buss bars would work better if you removed the oxidation layer from both sides of the buss bars, and also did a light sanding on the aluminum on the battery themselves -- and of course liberally used the anti-oxidation goop everywhere you sanded.
I'd also be interested in seeing if using a brass or bronze stud and nuts would be better than the steel ones, as the brass or bronze should also conduct better.
I would be interesting to see a re-test with those changes....
Philip
Hi. Everyone is using nickel plated copper as busbars for cells with aluminium terminals. So it should be ok, even though nickel and aluminium are not 'friends' in terms of galvanic corrosion? Much less than aluminium and copper itself though.
Those ally bars could do with some surface grinding! Fantastic test, it seems that heat or not tells you how good/ bad the bus bars are. If one does not have the camera. Thanks again for your effort.
Thanks Jackie. The aluminium bars will definitely work but need some treatment, sanding and no-ox-id paste. I'm just not sure how long this treated connection will last.
IME of automotive and marine electronics, 90% of issues are the connections, usually solder joints cracking followed by contact points needing a good sand down and re seat or replacing connection terminals
Surprisingly (not to me) crimp joints are by far the least problematic area of an electrical system 👍
Thank you. That's exactly what I found too. The IR camera doe s a great job revealing these weak points in your system quickly.
The crimp connection of this cable leading to the inverter seems to have a problem and gets really hot. I removed the heat shrink but could not really see a problem. I may just re-crimp it...
Hi, Andy, have you also tested stainless steel 304 nuts or serrated stainless steel 304 nuts would change the resistance of the same bus bars with same torque, would different nuts affect the current flow of the bus bars and results of your BMS? How about adding a layer of aluminum foil under bus bars or above bus bars to reduce resistance? I am going to use nickel plated bus bars with serrated stainless steel 304 on batteries in series, then apply dielectric grease to prevent corrosion and arching but now I would consider to use graphite grease to reduce resistance and corrosion without attracting dust. I am going to get a clamp meter as my multimeter would not test current other than 1.5V and 9V batteries. I figure this might be related to contact resistance and I am sure that different torque would even change voltage and current.
Not a problem if a busbar acts like a spring,one is supposed to compress the cells anyways, woven busbars can change in length too like your underpants even if I use neighter of them.
I'm using cable/braided crimped, so that at least the ring lugs can flex for the terminals that aren't perfectly flat next to eachother.
Yeah, that sounds like a good solution and will work perfectly.
@@OffGridGarageAustralia hope so ;) Mind you, this is a non-stationary solution, so I figured using flexible, given the vibrations, would be better anyway.
The question now is, why do you use those aluminum bus bars for your build? They seem to have perpetual problems. I drilled and tapped (for the sense leads) the nickel plated copper bus bars that came with my EVE LF304 cells. I was worried about them only being 2mm thick and copper, but there seems to be enough threads for a sufficient connection.
To test, learn, explore and... share 😉
Yes, I did the same with the Cu bars and the thread is enough for the balance cables.
Hi Andy, great test, thank you! This confirmed my gut feel that the original bus bars are fine. About the flexi-Ali bus bars "don't fit" I think that applies only for your huge batteries, for the "normal" sized ones they probably would be fine. Right?
The original busbars are actually pretty good considering they are 'free'.
No, that does not matter which cells you use. The EVE LF280/LF304 have the same terminal distance. I've got some new ones now which have the welded stud and they have different distances between the termerminals.
@@OffGridGarageAustralia I was referring to the 176Ah (which I use) or even lower - the "poor people" choice 😉, they are definity slimmer. SRY for not mention it before.
What is the heat reating of the wires ? Generaly is 70 c to get more then 30 40 is not good at all .the onley solution is biger wires.also you need an adapter in order to connect aluminyum to coper .
It does not say anything on the wires. These are the ones which came with the Renogy inverter. I have to check the crimping as this seems to be the issue.
@@OffGridGarageAustralia we had the same issu with ac pv brakers when we use adapter to coper they stop heating
It worth to chech with dc