You may need to be concerned about the type of metal of your bolts with the Aluminium. If they are dissimilar metals the reaction would potentially cause resistance and heating. So, a bit of grease may be in order. Also, I would widen the bolt hole slots 1 mm inline with the bar to account for expansion/movement. With no way to handle expansion, you could loosen or even break things.
As well as slot the holes in the bus bars vertically to allow for movement perhaps you could use a longer bolt with a cut down stiff spring & washer to keep tension on the bus bar but allow it to move. Loctite would help the bolt threads unwinding over time but not sure how that would affect conductivity.
I have a question. I have three 100 amp hour . Redodo batteries(12 volt )on a 6 post bus bar. and I want to add a fourth battery however I only have six positive posts on my bus bar. I already have three positive cables from my three batteries one on each post of my positive bus bar and I also have two Victron smart charge controllers one on each post and my Victron Phoenix 1200 watt inverter and it is on its own post that’s six. How could I add another battery(total four batteries at 12 V) is it advisable to double stack that fourth battery positive Cable onto one of the 6 bus bar posts??? and if so, which post or should I use???or should I make a jumper out of flexible, welding, cable, and add an additional positive bar to my existing positive busbar to give me more posts/terminals to work with???
Hello Andy ! Cheers for the entertainment as usual !! Always smiling ! I am living off grid myself and always read the comments as everyone is an expert and maybe that helps us all ! I love copper and would of done copper buss bars i might send you a nice pair for a future project i get big long nice looking bits and pieces from time to time from power house upgrades !! Real and old copper ! Keep up the great video’s in SUNNY STRAYA mate !!
FYI: Without any grease on aluminum, humid air will very quickly oxidize it. If your connections are sealed tight, it takes a long time for the oxidation to creep in, but grease will block it entirely. Also, the way to make the busbars safe is to get another vented battery cabinet and put that thing inside it.
Aluminum is a highly reactive metal and oxidizes almost instantly with atmospheric oxygen, nothing to do with moisture. Scratch aluminum to remove the oxide layer and it takes about 20 seconds to form a new one.
As an electrician I use noalox electrical antioxidant compound on aluminum electrical connections. You also have to be careful about your aluminum terminations because aluminum has a greater thermal expansion than copper. Your connection method needs to be listed for aluminum or you will constantly be dealing with loose connections.
Well to be fair you still want the heat shrink there because to turn the batteries off and on you are going to have to reveal the bus bars. So yeh I would totally cover them in heat shrink in this case. If you could turn the batteries off without exposing the bus bars then yeh sure a cabinet would be sufficient. Or if you used wires to connect to bus bars within a cabinet that were not easily accessible with your hands.
Nice to find an Aussie channel for all this stuff. The yanks are truly spoilt for choice, compared to us down under! Love the wrench casually sitting atop the unit, with two proud, 51.2v high amp bus bars right next to it 😂
Hi Andy. Your heat shrink size looks fine. The heat shrink bubbles like that because when it hits cold bus bar. If you heat the bus bar up with the heat gun a little it will help. You can also put a small ruler under it while shrinking and stretch the heat shrink while shrinking. Or just keep the heat on it a bit longer to heat the bar up a bit more. Heat shrinked plenty copper bar building switchboards😉
Stout looking busbars. I thought I was on the Pask Makes channel with all the filling - LOL. Currious what a clamp meter would show when you turned the third battery on. Wonder if it matches the BMS. Great show. thanks for sharing. Poor Joe's shirt - LOL.
Hi Andy, I'm also in Aus. Shoot me the dimensions and I'll design some snap on covers for the bolts if you like and print them for you. Can be my little donation for all you efforts with the channel we all love. 👍
It is best to connect the cables on opposite ends of the bus bars to help with equal current sharing between the modules. I am running copper bus bars myself on my battery system. Those terminals generally have quite a bit of flex so thermal expansion may not be a major issue with solid mounted bus bars.
Nohhh, not for such bus bars, they can be connected from one site easily. I have done the same in my battery shelf and have never had any issues with uneven charged batteries. 250A charging and discharging current. You may want to do this for larger batteries, with more in parallel and also higher currents but for such a baby battery, that would be overkill. Also, there is no access from the bottom...
@@OffGridGarageAustralia With only 3 modules and such big bus bars, current sharing is generally not an issue. I am just considering best practice. I have 5 modules and run at low rates, I do notice the closest battery finish charging 1% ahead but that is minor. I don't remember if any NoAlOx was applied or not, but some type of corrosion inhibitor should be applied to aluminum to avoid oxide related increases in resistance.
On the lighter-side: I only got 6.5 seconds of intro music. It does set the tone, I start bouncing my head, It is a cool little riff and it peaks interest in what Andy is going to enlighten me with. On the serious-side: Everyone will comment on how they can improve what they see but do not actually put the time in to do it.
OK, noted. I'll do more music next time! 🎸 Yes, thanks for your appreciation of my job! 🛠 I agree, a lot of comments but not many have done it themselves 😉
Does it make any difference on charging or discharging if you place the main wires to the bus bar on the same ends or opposite ends of the bus bars? I have heard that to charge the batteries evenly and drain them evenly it is best to put the main wire connections on opposite ends.
I would think that would be good, but if your bus bars are a larger amp capacity than would usually flow though them, if resistance is low, probably wouldn't make much difference.
Generally, no. Working with mutiple cell batteries is what makes that pointless. For the most part, if the batteries are of same capacity, than it won't matter. Whichever battery needs the power, will get it if the others don't. Good healthy batteries at same capacity will discharge equally as well. As the power leaves one cell, the other cells than pour out the power as they now have higher voltage potential, thus relatively insuring all will charge and discharge at the same time. Real life isn't paper however. While those 3 banks may be 10,000mah, one may be 10,234 while the other is 10,582, and the last being 10,334. You'll want to charge to lowest rating, charging to higher will eventually damage the cells of the lower banks. Back to the main question, no, it doesn't matter where on the bar the charge/discharge is as long as resistance is low.
A tip to throw in the toolbox for future reference. A power circular saw makes short work of aluminum stock machining. A finish blade having as many teeth as readily available for the saw diameter you have and carbide tipped teeth. Makes beautiful cuts that require little or no finishing after the cut. When making cuts don't be afraid of leaning into it. It will cut as easily or easier than the same size block of wood. Please don't skip the eye protection. Many fine chips will fly. Best not done in the presence of electrical gear without proper shielding.
That will effect the max current. Lets say it's a 8mm drill hole, than it would be around 10x20 that would limit the current to 160A. The bold will take some current also, so it will be a bit above that.
or a circular saw with the blade retracted so that 1mm is above the cutting plane, add stops to limit movement then cut a few passes, transverse, diagonal and side to side.
Hi Andy. The way you connected your load means that top battery will work harder than the bottom battery. For more even current flow it would be better to connect load to opposite sides of the busbar, so for example + to the top of the positive busbar and - to the bottom of the negative busbar (not both at the top). It will be great to see what difference will it make to the current flow through each battery. Sounds like an idea for an experiment :) many people don't realize that it will make a difference how you connect your load to parallel batteries.
Over the life of these batteries though even with the extremely flat discharge curve that is not going to be much of an issue as long as they get time most days to charge up fully and the loads are mostly below 150 amps. These busbars are capable of carrying far more power than the system is likely ever going to draw from them so the voltage drop down the length of the busbars is probably not enough to really matter. Sure he could do things to minimize it like making one connection at the top and the other at the bottom but it's probably not going to matter enough. This is probably only going to be an issue if the demand on the system is over 300 amps sustained during a prolonged discharge every day for its entire life. LiFePO4 cells are typically considered end of life at 60-70% of their original capacity. The failure rate goes up substantially per cell as they continue to be cycled beyond that point. Most of these installations will reach their limit due to calendar aging, before they ever reach that limit via cycle life. It will make sense to replace them in 20-30 years just to get the additional capacity back. I would also venture to guess DIY people like Andy will keep tinkering and building for years to come; so the system we see today will look drastically different over time, as more stuff is added and the batteries age. The point I am making is that it will likely not make a big difference over the life of these batteries, the size of the busbars, and the loads that will be put on each part of the system.
it isn't required do the math and you will see the voltage drop at the maximum current is a fraction of a volt across the busbar from memory it works out to be 0.07v and considering the busbars area vs the cables if 1 cable needs to be even a fraction longer to make that connection you have instantly cancelled out any benefit
4:13, to bits of copper sheet bent 90 degrees in the jaws of your vice would do the trick. At 22:00 I would likely try some clear acrylic bus-bar covers 'bended' and notched to fit over them. I'd drill and tap the busbars and use nylon screws to hold them in place, and 3d print some terminal covers for the top of the buss bar connections, or cut them shorter and connect the cables in the middle or bottom of the rack.
I like the bended acrylic covers. Maybe I can bend them snap onto the square bar or terminal. I have some leftovers from the acrylic work I did in the battery shelf. Good thinking, thanks!
@@OffGridGarageAustralia Andy, I was thinking that Sign and display shops and industrial supply sources, often use clear acrylic U-channel and square tubing stock, and even flexible colored PVC channel, and some styles are bended or extruded to be narrow at the open and help grip
Painters tape is a great way to find holes across a weird space. put tape where you know you want holes, pull tape up and put on bar, poof measurements are perfect always =)
Hi Offgrid-Garage. Great video. Two notes of observation: 1. Safety: That uninsulated spanner on top of the batteries just next to the end of busbars......uuhhhh...not advisable, especially for the viewers. I know you are experienced enough not to make a mistake but the viewers need to know, that it is extremely dangerous to put uninsulated metal tools on top of any battery ( “Do not try that at home” ), because things could go “South” pretty rapidly. All tools should be kept on the floor away from the battery whenever you are working with batteries. 2. When connecting output cables of paralleled battery bank, it is advised that the two output cables (positive and negative) be connected at the far opposite ends of the bus bars. By that I mean for example; positive out cable connects at the top of the left bus bar, and the negative out cable connects at the bottom of the right bus bar. Reason? Because this ensure a balance of currents flowing through each battery pack, since every conductor of current has some finite length thus some finite resistance and therefore when large currents are flowing, these resistances can cause imbalance of currents. Once again for the sake of viewers, it is “industry standard practice” to connect output cables at the opposite ends of paralleled batteries of a battery bank. Thanks and regards.
Hi! Probably someone suggested this but it'd be easy to design a cap for the battery terminals, there seem to be holes on the sides of the brackets that can be utilized for something sturdy and safe. Also, I don't think you should extend the bus bars beyond the top of the battery because you can just connect the cables to one of the terminals. That way you have no metal sticking out and vulnerable to metal touching it and causing all hell. And I agree with some of the comments here, grease wasn't the problem before, it must have been corrosion. Not using grease on the mating surfaces will absolutely cause corrosion and at these currents they could get hot when that happens. Really nice solution otherwise, this looks way more sturdy and with way less points of failure than a bunch of crimped cables.
Yeah, I was hoping for the inverter to test as I mentioned and maybe the longer busbar will come in handy at this point, so I didn't want to cut them prematurely.
Hmm. Its nice that the bus bars fit the slots. I'm a bit worried about the contact area though. If it were copper I wouldn't be as worried as the copper will deform a bit to snuggle up. But that is mighty thick aluminum... it might not deform enough to make a solid contact. Also, won't the aluminum oxidize? Those are (I assume) nickel plated contacts, but the aluminum bus bar is (?) just straight aluminum. The potential issue is that you get arcing from micro-gaps between the aluminum and terminal contacts. -Matt
If the terminals are not designed to handle any other metals than copper or steel, it may be that the aluminum may get very hot from corrosion because of the metallic differences between the metals. There is a history of mobile homes catching fire from aluminum wiring because the terminations couldn’t handle aluminum.
remove the black plastic/rubber trim off the 2nd and 3rd battery from the bottom and then the brackets will line up correctly. It looks like they did not account for the spacing of the trim.
I was thinking the same thing. Connecting in the middle at the second battery connection would spread the load more evenly and could handle up to 3 times as much.
Hallo Andy, jetzt schau ich schon länger Deine Beiträge und plötzlich taucht in Deiner Garage ein Schild von der nordhessischen Fuldametropole Kassel auf und hat mich total überrascht. Von daher musste ich Dir einfach ein paar Zeilen mit vielen lieben Grüßen aus Kassel schreiben und mach weiter so, Klaus
I used made alluminium bars cut from angle extrusion, I just sanded and cleaned them just before assembly to prevent oxidization, it made for a far cleaner looking instal than the connectors that came with it which I couldnt use anyway because of the different length bolts needed at the points where those connectors need to be stacked. I have since learnt that a galvanic reaction happens because one of the terminals of the lfp cells is copper which could be creating problems but its been running fine for nearly 4 years now. I will take it all apart and re sand and clean it to see if there is a difference. Perhaps for a high power application like an Ev it might not be the best way to go but for a lowish power instal its fine.. A tip for lining up all the bolts on the bar I use promite and dab a bit on each bolt head then press the bar against them all to mark the positions to drill.
For the cover, Perspex bends really easily, sandblast AG on the surface. You could have drilled the 8mm holes at 90 degrees near the middle and used less length. The 90 degrees current shift would help the flux capacitor.
Very clean looking, but are you worried at all about those aluminum bus bars fitting so tightly? Aluminum expands and contracts more so than other metals.
Have you considered using 16mm bus bars? Also, copper washers work well for interfacing bus bars with contact pads. Soft copper compresses nicely and form an "electric gasket". And nice idea with the "loin cloth". You should be able to just shrink wrap the tops. Cut it off if you need access later, not a big deal, you don't need access very often and heat shrink is cheap for the protection it provides. Thanks for the video! ps.. use wood slats as shims to protect soft metals in a clamp.
Thank you. Yeah, 16mm, right 😄 I don't want to heat shrink the top as I often take of the cables off and connect it to other batteries... Still unsure what to do here... I could use a heat shrink and not fully shrink it so it only sits loose on the top and can be slid back over the cable.
Hi Andy, with the ampere calculation of the diameter you commit a fallacy. The holes for the screws must be subtracted from the cross section, since the screws do not represent a solid connection to the busbar. But you have enough safety margin 🙂
Yes, smaller bus bars would have been easier. I also would have but them just long enough to span the three batteries and then attach the external cables to the same bolts as the center battery connections. This minimizes the average resistance to each battery and also removes the bars extending above the top battery. And I would have used some grease to prevent oxidation in the future as that will become a problem.
Ive had my server rack batteries like this but with twin copper bus bars on each side for the last 4 months. all good so far. expect its a bit of a ball ache to remove a battery if needed.
Thank you for showing your thought processes and work. I worked for years in a data center which was powered by AC and -48 vdc. If a product came with exposed busing or terminals, I would adapt a small plastic bin designed to separate hardware in a drawer. I would use tin snips to cut it to fit around the exposed metal, and attach it with Velcro. I am curious why you didn't use a spacer to bring the bus bar away from the connection without filing? All our bus bars were copper, but if aluminum wire was ever present from the factory, we used a product called no-alox or de-ox to make a superior connection. Poor connections are a safety hazard and protecting a room full of billions of dollars in servers was paramount.
Thanks for your tip. A spacer was on my list but I would have to file it as well (unless buying a 16x16mm piece of aluminium)\. I didn't go down that route as it a) didn't look great, b) added more resistance between all the pieces and c) didn't fit with the back plates mounted on the batteries. Filing was the only solution at the time.
Idea for the top part. You can use paint on electrical tape. Also, you'll want to grab the positive and negative from opposite ends to balance the load better. There is resistance in the bar, and the voltage will drop between batteries. This will only be a problem for larger loads.
Thank you. I still have such isolating paint from our battery shelf built. The problem is, that I need to take these connections off frequently, when I test batteries. Connecting them opposite sites makes sense, if the interconnections are thin. With such a big dimensioned bus bar, it makes no difference. Especially with LiFePO4 and the very flat voltage curve, I found no benefit. The battery banks will balance out when they are almost fully charged.
Nice video! The tops -- cut one piece of shrink wrap long enough that it covers the top (like 22mm) and cut the loop and place on top. Then cut another short piece of shrink wrap and put it over the bar, which will hold the top shrink wrap on the bar. Then heat and shrink the wrap and cut off any extra. Might work, just a theory/idea. Cheers!
@@OffGridGarageAustralia It would just cover the top of the bar. First 1-3mm from the top, above the bolt holes. Basically a tiny busbar condom over the top and first 1-3mm of the sides.
Use a 3d Printer to create caps for all of your bolt holes. Andy, what would happen if each of the polos had different cells in them. Lets say the top one had LF 304's and the two bottom ones had LF 280's. Would they eventually equalize or would the LF 304 have more capacity than the LF280's?
quick question: when pulling voltage and amps and putting in voltage and amps, I thought./ maybe think, it is best to pull the + at one battery and the - from the other furthest with multiple batteries ... so V and A balance equally to all batteries... my system is tiny tiny compared to your units .. so maybe it doesn't make a difference to do it the way you did/do.
it makes no difference here the voltage drop even at the extreme ends of the busbars is less than 0.1v at their maximum current capacity which the system can't supply and none of the monitoring systems could even measure such a small difference
You could design, and 3D print, snap-on plastic protective covers using these indentations on the sides of the positive and negative poles on this battery pack.
@@OffGridGarageAustralia If you buy a 3D printer, I'm sure you'll be in awe of your new toy. You are just the type of person who will fall in love with this toy. It can even help you a lot to make parts for a new base for your solar panels that can follow the movements of the sun.
Looks like you could use those square holes to mount a big acrylic gate down in front of the whole lot? Slide the gate up when you need to flick a switch or hit a button or whatever, have nothing but insulated wiring coming out from the top (or bottom). That or drill strategic holes so you can poke a tool in for resetting or flicking switches.
If you have a miter saw you can cut aluminum with most wood blades. Just check the manufacturer's instructions. Makes quick work of things like this if you set the stops to 1mm and use stop blocks for how far you want to move left to right.
Hallo Andy, maybe a piece of cable duct that fits/clamps onto the Terminals isolator to cover the Terminals an even the busbars too ? (Für die Busbars und Terminals der LF280k Zellen nehme ich z.B. geschlitztes Wellrohr als Schutz.)
While it would work, it somehow just feels wrong to file down the battery terminals. Theres the saying "if it's stupid but it works, it isn't stupid" but even so, that doesn't mean it's a professional solution. (not to imply the idea stupid either but you get the gist).
Andy, i plan to connect four 280ah 200a BMS wall batteries in parallel. Batteries are on the wall next to each other. I m thinking of using a two 2m long 40x10 aluminum busbars running under the batteries and then short 95mm2 cables to each battery. 40x10 aluminum busbars gives me 320A. As my inverter is max 240a it should be enough. However I did not find any information how long busbars can be. Is 2m ok?
Hy Andy, if there is a groove on the busbar then the surface area is bigger what means better for electrical flow but you don’t have a milling Maschine. Like I know electricity is flowing on the surface.
2:50 : I think the formula is not for all use cases. Actually it gives a value that represents the generated heat in the conductor. If you reduce the cross section only at the small part where the space constriction is, then I guess the heat can conduct fast enough away from that place so that the temperature there will not reach the same value as if the whole bar was made with the reduced cross section. Heat generated gets worse by 20^2/(18*20) = 1.111 (in that section). btw, if you retained the square shape to get the new cross section of 18*20=360 it would be a square rod 18.974*18.974 and then you would also loose cooling surface by 0.949 (and the bar would not fit in). But because of the new rectangular shape you only loose cooling surface by 0.975. So that's fortunate. And you get cooling by the screw that connects the bar to the terminals.
Not with bus bars, that does not make any difference. When using cable connections with less ampacity, yeah, maybe. I have the same setup and connection from the top in my battery shelf. The Bus bars are so large, the batteries are all charging equally.
Yeah that is silly it is resistance that makes that a factor but the busbars is 33ų Ohms or 0.007V at a full 220A basically not measureable numbers on standard equipment even the best bms couldn't measure that it would be less than the tollerances in the batteries themselves
Regarding the busbar calculator a standart copper busbar 2x20 is only suitable for 48A....? Lynx should then have have a 20x42 busbar to handle the 1000A.... It seems they foregot to regard the length.
You may need to be concerned about the type of metal of your bolts with the Aluminium. If they are dissimilar metals the reaction would potentially cause resistance and heating. So, a bit of grease may be in order.
Also, I would widen the bolt hole slots 1 mm inline with the bar to account for expansion/movement. With no way to handle expansion, you could loosen or even break things.
As well as slot the holes in the bus bars vertically to allow for movement perhaps you could use a longer bolt with a cut down stiff spring & washer to keep tension on the bus bar but allow it to move. Loctite would help the bolt threads unwinding over time but not sure how that would affect conductivity.
I have a question. I have three 100 amp hour . Redodo batteries(12 volt )on a 6 post bus bar. and I want to add a fourth battery however I only have six positive posts on my bus bar. I already have three positive cables from my three batteries one on each post of my positive bus bar and I also have two Victron smart charge controllers one on each post and my Victron Phoenix 1200 watt inverter and it is on its own post that’s six. How could I add another battery(total four batteries at 12 V) is it advisable to double stack that fourth battery positive Cable onto one of the 6 bus bar posts??? and if so, which post or should I use???or should I make a jumper out of flexible, welding, cable, and
add an additional positive bar to my existing positive busbar to give me more posts/terminals to work with???
Hello Andy ! Cheers for the entertainment as usual !! Always smiling ! I am living off grid myself and always read the comments as everyone is an expert and maybe that helps us all ! I love copper and would of done copper buss bars i might send you a nice pair for a future project i get big long nice looking bits and pieces from time to time from power house upgrades !! Real and old copper ! Keep up the great video’s in SUNNY STRAYA mate !!
Thanks a lot. I could not find any copper busbar in this size unless I bought a 4m full length. The aluminium bar works great though. Cheers.
Andy, Congratulations! You do some very creative projects.
Thank you very much!
Artisanally crafted bespoke busbars.
Andy, should take custom orders for those!
FYI: Without any grease on aluminum, humid air will very quickly oxidize it. If your connections are sealed tight, it takes a long time for the oxidation to creep in, but grease will block it entirely.
Also, the way to make the busbars safe is to get another vented battery cabinet and put that thing inside it.
smiles .. almost instantly ..
@timg6850 Are the battery terminal blocks aluminum? Is the air not humid with moisture in the morning?
Aluminum is a highly reactive metal and oxidizes almost instantly with atmospheric oxygen, nothing to do with moisture. Scratch aluminum to remove the oxide layer and it takes about 20 seconds to form a new one.
As an electrician I use noalox electrical antioxidant compound on aluminum electrical connections. You also have to be careful about your aluminum terminations because aluminum has a greater thermal expansion than copper. Your connection method needs to be listed for aluminum or you will constantly be dealing with loose connections.
Well to be fair you still want the heat shrink there because to turn the batteries off and on you are going to have to reveal the bus bars. So yeh I would totally cover them in heat shrink in this case. If you could turn the batteries off without exposing the bus bars then yeh sure a cabinet would be sufficient.
Or if you used wires to connect to bus bars within a cabinet that were not easily accessible with your hands.
Nice to find an Aussie channel for all this stuff. The yanks are truly spoilt for choice, compared to us down under! Love the wrench casually sitting atop the unit, with two proud, 51.2v high amp bus bars right next to it 😂
Glad you are better again, hope Silke is also back to being better!
Hi Andy. Your heat shrink size looks fine. The heat shrink bubbles like that because when it hits cold bus bar. If you heat the bus bar up with the heat gun a little it will help. You can also put a small ruler under it while shrinking and stretch the heat shrink while shrinking. Or just keep the heat on it a bit longer to heat the bar up a bit more. Heat shrinked plenty copper bar building switchboards😉
Stout looking busbars. I thought I was on the Pask Makes channel with all the filling - LOL. Currious what a clamp meter would show when you turned the third battery on. Wonder if it matches the BMS. Great show. thanks for sharing. Poor Joe's shirt - LOL.
Cute play on words Andy. Bastard filing is SOOO fun…
Well, it is... all this hard work for half a handful of aluminium flakes...😂
I really love ❤ you’re sense of humor!! Thanks for the Knowledge on these thing.
Interesting battery design. And nice solution in the end
Thank you!
Hi Andy, I'm also in Aus. Shoot me the dimensions and I'll design some snap on covers for the bolts if you like and print them for you. Can be my little donation for all you efforts with the channel we all love. 👍
Expansion/ Contraction on aluminum is real, that has to be allowed in your builds. Some flexibility somewhere is always a plus.
The easiest solution is to leave all the bolts just a touch loose so things can move, especially when under load.
It is best to connect the cables on opposite ends of the bus bars to help with equal current sharing between the modules. I am running copper bus bars myself on my battery system. Those terminals generally have quite a bit of flex so thermal expansion may not be a major issue with solid mounted bus bars.
Nohhh, not for such bus bars, they can be connected from one site easily. I have done the same in my battery shelf and have never had any issues with uneven charged batteries. 250A charging and discharging current. You may want to do this for larger batteries, with more in parallel and also higher currents but for such a baby battery, that would be overkill. Also, there is no access from the bottom...
@@OffGridGarageAustralia With only 3 modules and such big bus bars, current sharing is generally not an issue. I am just considering best practice. I have 5 modules and run at low rates, I do notice the closest battery finish charging 1% ahead but that is minor. I don't remember if any NoAlOx was applied or not, but some type of corrosion inhibitor should be applied to aluminum to avoid oxide related increases in resistance.
On the lighter-side:
I only got 6.5 seconds of intro music. It does set the tone, I start bouncing my head, It is a cool little riff and it peaks interest in what Andy is going to enlighten me with.
On the serious-side:
Everyone will comment on how they can improve what they see but do not actually put the time in to do it.
OK, noted. I'll do more music next time! 🎸
Yes, thanks for your appreciation of my job! 🛠 I agree, a lot of comments but not many have done it themselves 😉
Andy when batteries are installed in telecom installations we never used any paste.
The most important thing was to torque the connections.
Yes, say NO to paste!
You could slip a piece of PVC pipe/conduit over the cable end of the busbar, 50mm ID might work.
It doesn’t matter how others would do it, what you did wrong / right blah. It’s still entertaining 👍 and worked
Thanks, yeah, I guess it is working quite well!
Does it make any difference on charging or discharging if you place the main wires to the bus bar on the same ends or opposite ends of the bus bars? I have heard that to charge the batteries evenly and drain them evenly it is best to put the main wire connections on opposite ends.
I would think that would be good, but if your bus bars are a larger amp capacity than would usually flow though them, if resistance is low, probably wouldn't make much difference.
Generally, no. Working with mutiple cell batteries is what makes that pointless. For the most part, if the batteries are of same capacity, than it won't matter. Whichever battery needs the power, will get it if the others don't.
Good healthy batteries at same capacity will discharge equally as well. As the power leaves one cell, the other cells than pour out the power as they now have higher voltage potential, thus relatively insuring all will charge and discharge at the same time.
Real life isn't paper however. While those 3 banks may be 10,000mah, one may be 10,234 while the other is 10,582, and the last being 10,334.
You'll want to charge to lowest rating, charging to higher will eventually damage the cells of the lower banks.
Back to the main question, no, it doesn't matter where on the bar the charge/discharge is as long as resistance is low.
Excellent video, thank you. But your patience is legendary !! I would have swapped out for a 16mm bar lol.
That was cool, thanks for the effort and your awesome energy
Thanks for the feedback. Appreciate it!
3d print little box covers in desired color. Have done this on my EG4's and they work great and look great.
A tip to throw in the toolbox for future reference. A power circular saw makes short work of aluminum stock machining. A finish blade having as many teeth as readily available for the saw diameter you have and carbide tipped teeth. Makes beautiful cuts that require little or no finishing after the cut.
When making cuts don't be afraid of leaning into it. It will cut as easily or easier than the same size block of wood. Please don't skip the eye protection. Many fine chips will fly. Best not done in the presence of electrical gear without proper shielding.
Hi Andy, 10 out of 10 on your Loincloth idea! 👏👏👏
Love from 🏴
Gary
All that file work. Considering what you have into all the solar equipment a bench top mill would be cheap and very handy.
Seeing you calculate the amps and later drilling the holes got me thinking, it's not 18x20 anymore is it? Does it matter? 😅
That will effect the max current. Lets say it's a 8mm drill hole, than it would be around 10x20 that would limit the current to 160A. The bold will take some current also, so it will be a bit above that.
you put a bolt in the holes also the terminals are another chunk of metal so in reality they make no difference
Ever thought about using a router - alu can be machined just with the wood bits as well ...
Or an electric planer
@@rattusfinkus ... If you have such a narrow one at hand ...
or a circular saw with the blade retracted so that 1mm is above the cutting plane, add stops to limit movement then cut a few passes, transverse, diagonal and side to side.
Hi Andy. The way you connected your load means that top battery will work harder than the bottom battery. For more even current flow it would be better to connect load to opposite sides of the busbar, so for example + to the top of the positive busbar and - to the bottom of the negative busbar (not both at the top). It will be great to see what difference will it make to the current flow through each battery. Sounds like an idea for an experiment :) many people don't realize that it will make a difference how you connect your load to parallel batteries.
Over the life of these batteries though even with the extremely flat discharge curve that is not going to be much of an issue as long as they get time most days to charge up fully and the loads are mostly below 150 amps. These busbars are capable of carrying far more power than the system is likely ever going to draw from them so the voltage drop down the length of the busbars is probably not enough to really matter. Sure he could do things to minimize it like making one connection at the top and the other at the bottom but it's probably not going to matter enough. This is probably only going to be an issue if the demand on the system is over 300 amps sustained during a prolonged discharge every day for its entire life.
LiFePO4 cells are typically considered end of life at 60-70% of their original capacity. The failure rate goes up substantially per cell as they continue to be cycled beyond that point. Most of these installations will reach their limit due to calendar aging, before they ever reach that limit via cycle life. It will make sense to replace them in 20-30 years just to get the additional capacity back. I would also venture to guess DIY people like Andy will keep tinkering and building for years to come; so the system we see today will look drastically different over time, as more stuff is added and the batteries age.
The point I am making is that it will likely not make a big difference over the life of these batteries, the size of the busbars, and the loads that will be put on each part of the system.
Agree. Check Tichelmann circuit. Very simple solution to this problem.
it isn't required do the math and you will see the voltage drop at the maximum current is a fraction of a volt across the busbar from memory it works out to be 0.07v and considering the busbars area vs the cables if 1 cable needs to be even a fraction longer to make that connection you have instantly cancelled out any benefit
For an interim insulation you can put some small PET bottle(neck) parts over the ends and shrink them with your heat gun to fit ... cheap and durable.
I was thinking something similar: use PVC tubes, they can be (de)formed easily too.
It is definitely pretty with the bus bars as opposed to wires and more functional as well. 👍🏻
4:13, to bits of copper sheet bent 90 degrees in the jaws of your vice would do the trick. At 22:00 I would likely try some clear acrylic bus-bar covers 'bended' and notched to fit over them. I'd drill and tap the busbars and use nylon screws to hold them in place, and 3d print some terminal covers for the top of the buss bar connections, or cut them shorter and connect the cables in the middle or bottom of the rack.
I like the bended acrylic covers. Maybe I can bend them snap onto the square bar or terminal. I have some leftovers from the acrylic work I did in the battery shelf. Good thinking, thanks!
@@OffGridGarageAustralia Andy, I was thinking that Sign and display shops and industrial supply sources, often use clear acrylic U-channel and square tubing stock, and even flexible colored PVC channel, and some styles are bended or extruded to be narrow at the open and help grip
Danke!
Da hat der Micha was von seinem Putzgeld spendiert. Danke Dir vielmals!
Painters tape is a great way to find holes across a weird space. put tape where you know you want holes, pull tape up and put on bar, poof measurements are perfect always =)
Hi Offgrid-Garage.
Great video. Two notes of observation:
1. Safety: That uninsulated spanner on top of the batteries just next to the end of busbars......uuhhhh...not advisable, especially for the viewers. I know you are experienced enough not to make a mistake but the viewers need to know, that it is extremely dangerous to put uninsulated metal tools on top of any battery ( “Do not try that at home” ), because things could go “South” pretty rapidly. All tools should be kept on the floor away from the battery whenever you are working with batteries.
2. When connecting output cables of paralleled battery bank, it is advised that the two output cables (positive and negative) be connected at the far opposite ends of the bus bars. By that I mean for example; positive out cable connects at the top of the left bus bar, and the negative out cable connects at the bottom of the right bus bar.
Reason? Because this ensure a balance of currents flowing through each battery pack, since every conductor of current has some finite length thus some finite resistance and therefore when large currents are flowing, these resistances can cause imbalance of currents. Once again for the sake of viewers, it is “industry standard practice” to connect output cables at the opposite ends of paralleled batteries of a battery bank.
Thanks and regards.
Hi! Probably someone suggested this but it'd be easy to design a cap for the battery terminals, there seem to be holes on the sides of the brackets that can be utilized for something sturdy and safe. Also, I don't think you should extend the bus bars beyond the top of the battery because you can just connect the cables to one of the terminals. That way you have no metal sticking out and vulnerable to metal touching it and causing all hell. And I agree with some of the comments here, grease wasn't the problem before, it must have been corrosion. Not using grease on the mating surfaces will absolutely cause corrosion and at these currents they could get hot when that happens. Really nice solution otherwise, this looks way more sturdy and with way less points of failure than a bunch of crimped cables.
Yeah, I was hoping for the inverter to test as I mentioned and maybe the longer busbar will come in handy at this point, so I didn't want to cut them prematurely.
A video on bus bars? Yes please!
Cool project Andy 👍
I like your sense of humor keeps me grinning …😅
Nice integration, Andy!
Hmm. Its nice that the bus bars fit the slots. I'm a bit worried about the contact area though. If it were copper I wouldn't be as worried as the copper will deform a bit to snuggle up. But that is mighty thick aluminum... it might not deform enough to make a solid contact. Also, won't the aluminum oxidize? Those are (I assume) nickel plated contacts, but the aluminum bus bar is (?) just straight aluminum.
The potential issue is that you get arcing from micro-gaps between the aluminum and terminal contacts.
-Matt
Not sure what paste he had , but many of the electrical ones are antioxidant .
If the terminals are not designed to handle any other metals than copper or steel, it may be that the aluminum may get very hot from corrosion because of the metallic differences between the metals. There is a history of mobile homes catching fire from aluminum wiring because the terminations couldn’t handle aluminum.
Aluminium attached to copper...have you tried using NoALox as a grease? Copper and aluminum just don't like being roomates for long periods.
Two years from now in can have a video on the heating connections. We used to use Chemfilm on aluminum that prevents the corrosion and is conductive.
Man, Andy , you are a real HOOT!
Thanks for entertaining us.
you're the man dear Andy
remove the black plastic/rubber trim off the 2nd and 3rd battery from the bottom and then the brackets will line up correctly. It looks like they did not account for the spacing of the trim.
92nd! no medals for me today! Hope you get back to 100% soon dude!
Would it improve the current flow if the external connecting cables were connected towards the middle of the bus bar?
I was thinking the same thing. Connecting in the middle at the second battery connection would spread the load more evenly and could handle up to 3 times as much.
Hallo Andy, jetzt schau ich schon länger Deine Beiträge und plötzlich taucht in Deiner Garage ein Schild von der nordhessischen Fuldametropole Kassel auf und hat mich total überrascht. Von daher musste ich Dir einfach ein paar Zeilen mit vielen lieben Grüßen aus Kassel schreiben und mach weiter so, Klaus
I used made alluminium bars cut from angle extrusion, I just sanded and cleaned them just before assembly to prevent oxidization, it made for a far cleaner looking instal than the connectors that came with it which I couldnt use anyway because of the different length bolts needed at the points where those connectors need to be stacked. I have since learnt that a galvanic reaction happens because one of the terminals of the lfp cells is copper which could be creating problems but its been running fine for nearly 4 years now. I will take it all apart and re sand and clean it to see if there is a difference. Perhaps for a high power application like an Ev it might not be the best way to go but for a lowish power instal its fine.. A tip for lining up all the bolts on the bar I use promite and dab a bit on each bolt head then press the bar against them all to mark the positions to drill.
For the cover, Perspex bends really easily, sandblast AG on the surface. You could have drilled the 8mm holes at 90 degrees near the middle and used less length. The 90 degrees current shift would help the flux capacitor.
Very clean looking, but are you worried at all about those aluminum bus bars fitting so tightly? Aluminum expands and contracts more so than other metals.
They would need a good portion of current and heat to expand that much. I'm not worried about that at all.
Lol. Funny how you said sorry for fileing over the line.
What is this battery again?
Do you have a link to purchase the Seplos batteries? Thanks for the content. Cheers
Have you considered using 16mm bus bars? Also, copper washers work well for interfacing bus bars with contact pads. Soft copper compresses nicely and form an "electric gasket". And nice idea with the "loin cloth". You should be able to just shrink wrap the tops. Cut it off if you need access later, not a big deal, you don't need access very often and heat shrink is cheap for the protection it provides. Thanks for the video!
ps.. use wood slats as shims to protect soft metals in a clamp.
Thank you. Yeah, 16mm, right 😄
I don't want to heat shrink the top as I often take of the cables off and connect it to other batteries... Still unsure what to do here... I could use a heat shrink and not fully shrink it so it only sits loose on the top and can be slid back over the cable.
Hi Andy, with the ampere calculation of the diameter you commit a fallacy. The holes for the screws must be subtracted from the cross section, since the screws do not represent a solid connection to the busbar.
But you have enough safety margin 🙂
Yep, got the plus and negative bus bars mixed up, but because these Seplos bms's are controlled on the negative, should be a-ok!
Is it normal M6 screws for the Weco 4K4 LT?
Yes, smaller bus bars would have been easier. I also would have but them just long enough to span the three batteries and then attach the external cables to the same bolts as the center battery connections. This minimizes the average resistance to each battery and also removes the bars extending above the top battery. And I would have used some grease to prevent oxidation in the future as that will become a problem.
Ive had my server rack batteries like this but with twin copper bus bars on each side for the last 4 months. all good so far. expect its a bit of a ball ache to remove a battery if needed.
Use liquid urethane casting kits for forming low cost custom insulators. Robust and good resistance material.
Thank you for showing your thought processes and work. I worked for years in a data center which was powered by AC and -48 vdc. If a product came with exposed busing or terminals, I would adapt a small plastic bin designed to separate hardware in a drawer. I would use tin snips to cut it to fit around the exposed metal, and attach it with Velcro. I am curious why you didn't use a spacer to bring the bus bar away from the connection without filing? All our bus bars were copper, but if aluminum wire was ever present from the factory, we used a product called no-alox or de-ox to make a superior connection. Poor connections are a safety hazard and protecting a room full of billions of dollars in servers was paramount.
Thanks for your tip.
A spacer was on my list but I would have to file it as well (unless buying a 16x16mm piece of aluminium)\. I didn't go down that route as it a) didn't look great, b) added more resistance between all the pieces and c) didn't fit with the back plates mounted on the batteries. Filing was the only solution at the time.
Idea for the top part. You can use paint on electrical tape. Also, you'll want to grab the positive and negative from opposite ends to balance the load better. There is resistance in the bar, and the voltage will drop between batteries. This will only be a problem for larger loads.
Thank you. I still have such isolating paint from our battery shelf built. The problem is, that I need to take these connections off frequently, when I test batteries.
Connecting them opposite sites makes sense, if the interconnections are thin. With such a big dimensioned bus bar, it makes no difference. Especially with LiFePO4 and the very flat voltage curve, I found no benefit. The battery banks will balance out when they are almost fully charged.
@@OffGridGarageAustralia For sure! The paint on tape is messy if you have to remove and reapply. Cheers mate keep up the good work!
Nice video! The tops -- cut one piece of shrink wrap long enough that it covers the top (like 22mm) and cut the loop and place on top. Then cut another short piece of shrink wrap and put it over the bar, which will hold the top shrink wrap on the bar. Then heat and shrink the wrap and cut off any extra. Might work, just a theory/idea. Cheers!
It needs to be detachable. I will take the cables off frequently to test other batteries...
@@OffGridGarageAustralia It would just cover the top of the bar. First 1-3mm from the top, above the bolt holes. Basically a tiny busbar condom over the top and first 1-3mm of the sides.
That is einfach a job for a milling machine --don't get me wrong --a good sharp file is one of my favorite tools.
Use a 3d Printer to create caps for all of your bolt holes. Andy, what would happen if each of the polos had different cells in them. Lets say the top one had LF 304's and the two bottom ones had LF 280's. Would they eventually equalize or would the LF 304 have more capacity than the LF280's?
FYI, GI busbars are Gas Insulated. Usually with high pressure SF6 (Sulfur Hexaflouride).
Cut, file, = work 😂 it’s looking good 👍
How was the heat on the bus bars once you put a load on the batteries for a while?
quick question: when pulling voltage and amps and putting in voltage and amps, I thought./ maybe think, it is best to pull the + at one battery and the - from the other furthest with multiple batteries ... so V and A balance equally to all batteries... my system is tiny tiny
compared to your units .. so maybe it doesn't make a difference to do it the way you did/do.
it makes no difference here the voltage drop even at the extreme ends of the busbars is less than 0.1v at their maximum current capacity which the system can't supply and none of the monitoring systems could even measure such a small difference
Looking sweet Andy. The busbars look so lucky better. What aluminium alloy in those busbars, 6060 ?
You could design, and 3D print, snap-on plastic protective covers using these indentations on the sides of the positive and negative poles on this battery pack.
Yeah, can't design that, wouldn't know how. I also don't have a 3D printer.
@@OffGridGarageAustralia If you buy a 3D printer, I'm sure you'll be in awe of your new toy. You are just the type of person who will fall in love with this toy. It can even help you a lot to make parts for a new base for your solar panels that can follow the movements of the sun.
Looks like you could use those square holes to mount a big acrylic gate down in front of the whole lot? Slide the gate up when you need to flick a switch or hit a button or whatever, have nothing but insulated wiring coming out from the top (or bottom). That or drill strategic holes so you can poke a tool in for resetting or flicking switches.
6:49 can you remove the plastic on that terminal?
If you have a miter saw you can cut aluminum with most wood blades. Just check the manufacturer's instructions. Makes quick work of things like this if you set the stops to 1mm and use stop blocks for how far you want to move left to right.
Counter sink the bus bar and use an hex bolt to secure bus bars leaving the bus bar flush.
Hallo Andy,
maybe a piece of cable duct that fits/clamps onto the Terminals isolator to cover the Terminals an even the busbars too ?
(Für die Busbars und Terminals der LF280k Zellen nehme ich z.B. geschlitztes Wellrohr als Schutz.)
What program are you using to monitor?
Hi Andy, just a thought, why don't you move your workshop into the "Big shed" then you would have more room?
👍👍great stuff
Andy. STOP 🛑 why didn’t you file down the plastic on the terminals. Then you could leave it 20x20 😮
Because the goal is to work with is provided
And you would void any warranty
How about getting 22x18 busbars?
While it would work, it somehow just feels wrong to file down the battery terminals.
Theres the saying "if it's stupid but it works, it isn't stupid" but even so, that doesn't mean it's a professional solution. (not to imply the idea stupid either but you get the gist).
My thoughts exactly when I saw him fitting them
Don’t forget about thermal expansion! Maybe larger holes or slots?
22:16 a rubber door stop would do it, with lugs down (as shown). They come in white
Heya, with those bush bars it looks much cleaner install. you cut to be crazy to do that with a rasp lol
Andy, i plan to connect four 280ah 200a BMS wall batteries in parallel. Batteries are on the wall next to each other. I m thinking of using a two 2m long 40x10 aluminum busbars running under the batteries and then short 95mm2 cables to each battery. 40x10 aluminum busbars gives me 320A. As my inverter is max 240a it should be enough. However I did not find any information how long busbars can be. Is 2m ok?
Are you sure the calculator for bus-bar ampacity is correct? 20X20 = 400mm2 aluminum = 400Amps on cable. Without insulation, even more!
This is the perfect job for a mini mill. They’re cheap at your local version of Harbor Freight
Muirhead Engineering in Archerfield can make up custom bus bars in alu, copper or other materials..
G I stands for Galvanized Iron
Always start all screws befor tightening so the holes line up better
Hy Andy, if there is a groove on the busbar then the surface area is bigger what means better for electrical flow but you don’t have a milling Maschine. Like I know electricity is flowing on the surface.
it's cross-sectional area not surface area that is the determining factor and it isn't flowing on the sufrace
Do you have a drop saw?
copper is much more conductive than aluminium, aluminium also oxidizes ...... why not try copper busbars instead? Nice job with the heatshrink
2:50 : I think the formula is not for all use cases. Actually it gives a value that represents the generated heat in the conductor. If you reduce the cross section only at the small part where the space constriction is, then I guess the heat can conduct fast enough away from that place so that the temperature there will not reach the same value as if the whole bar was made with the reduced cross section. Heat generated gets worse by 20^2/(18*20) = 1.111 (in that section). btw, if you retained the square shape to get the new cross section of 18*20=360 it would be a square rod 18.974*18.974 and
then you would also loose cooling surface by 0.949 (and the bar would not fit in). But because of the new rectangular shape you only loose cooling surface by 0.975. So that's fortunate. And you get cooling by the screw that connects the bar to the terminals.
Grüße aus Deutschland. Dein Zollstock hat es mir verraten.
You need to move either positive or negative cable to bottom. That way it will pull more evenly from batteries.
Not with bus bars, that does not make any difference. When using cable connections with less ampacity, yeah, maybe.
I have the same setup and connection from the top in my battery shelf. The Bus bars are so large, the batteries are all charging equally.
Yeah that is silly it is resistance that makes that a factor but the busbars is 33ų Ohms or 0.007V at a full 220A basically not measureable numbers on standard equipment even the best bms couldn't measure that it would be less than the tollerances in the batteries themselves
I am pretty sure that back of batteries have a metal cover piece to hide it all, indentation and slots on the sides are pretty clear indicator
Yes, they have. It's in the other Seplos Polo video. Not a great solution though.
ruclips.net/video/t3FiFvs1xBQ/видео.html
no grinder available ?! :)
Mr. Endy, we charge the plus in advance, but the minus must be charged from the bottom with such a connection.
Regarding the busbar calculator a standart copper busbar 2x20 is only suitable for 48A....?
Lynx should then have have a 20x42 busbar to handle the 1000A....
It seems they foregot to regard the length.
hello is it possible to parellel LIFEPO4 pack and Lithium iron NMC battery pack together with solar inverter?