I can't wait to get my batteries - just ordered last week. I'll be watching your videos again once they arrive. I'm still trying to decide what BMS I'm going to employ.
There are quite a few options for BMS. Just to further cloud the issue and make the decision more difficult, overkill solar just came out with a 16S/48V nominal version of their BMS system for around 130$, depending on options.
@@w3bb0y Sure. I got mine as part of a group buy from the DIY Solar Power Forum group: diysolarforum.com/threads/lishen-272ah-thread.12871 Send a PM to Michael B Caro and he will get you a quote. They usually do a group buy every month.
The blue foil will age over the years and establish contact between the aluminum cells. Positive is connected to the aluminum housing. Spacers must be placed between the cells. !!!
The only thing I would add and this has also been mentioned on diysolarforum is that aluminum oxide is not very conductive so wire brushing the terminal tops is the most important step. Perhaps you did that earlier but it forms very quickly so the antiox should be applied after buffing.
Thanks! I did in fact wire brush the tops previously. I also wiped away the oxide dust with 99% Isopropyl alcohol on a paper towel. I then immediately coated the terminals with No-Ox-ID. If I had to do it over again I would have inserted the studs into the threaded holes before applying the No-Ox-ID as some of it got inside the lip of the hole which had to be cleaned out with a qtip before inserting the locktited studs.
I put my lifepo batteries in parallel as one would do with most batteries and it clobbered the capacity. I lost about 30% compared to what I should have gotten. Differentilal voltages between various parallel groups connected in series went wild to the tune of several hundred millivolts. I thought my batteries were bad but tested them individually and in series and all was fine. Took them out of parallel and just put them in series and got the capacity I expected. Not sure why but you should do some tests first. My guess is that the complex nature of Lithium battery chemistry and the distribution of internal resistance inhibits equal charge sharing between the batteries like we would expect with most things connected in parallel. You might be better off with 4 independent batteries in series with a bms on each and paralleled at the whole battery level. I will be checking that configuration out eventually. Since these batteries take so long to charge it is a very time consuming endeavor to experiment. By the way, you might not expect it but the busbars and cables have a significant resistance compared to the internal resistance of the lifepo batteries. Mine did anyway as they were 1/16 " thick by 3/4 " and 3" long. Therefore, you might want to try and connect the parallel groups with 4 busbars between each group (one off of and to each battery terminal). I saw this recommendation but did not follow it and maybe that also contributed to my problems. Oh, excuse me, I just got a shot of your battery configuration and it looks like you are doing it as recommended. I will be very interested to know if you get the capacity you expect.
@@metagrid9453 I think it might help but I am skeptical that it would really solve the problem. Then again, maybe it was just my batteries and/or my setup. I think not though. I calculated that my busbars (1/16 X 3/4 X 3 inch) had a resistance of about 25% of the internal cell resistance. That is assuming that the BMS I used which gives an estimate of internal resistance was correct. That might be a big assumption. In any case, we are stuck with the internal resistance of the cells and they will differ between cells which means we will always get different currents through each cell. If the IR is close enough it might not be a super big deal but, as you probably know, once you get towards the ends of the charge and discharge cycle IR goes nuts pretty quick. I am very interested to see if you experience the same thing if you want to take the time to test it.
A lot of people mess up connecting batteries in parallel, as the obvious way isn't optimal: www.solar-electric.com/lib/wind-sun/Iota_balanced_charging.pdf
@@alharrison3255 Thanks for the article Al. Yes, I am familiar with the problem and had mine connected as shown in figure 3. Although that is not bad, the article says I can do better so good to know. Since I wrote my statements above I did find out that a significant part of the problem was a software bug in my BMS that made it give me inaccurate amp hour measurements. Despite a firmware release, the BMS problem is not fixed yet. Just installed another BMS firmware fix yesterday but have not tested it yet.
I realize that most of the contact is not the stud, but since stainless steel is poor conductor had you considered using brass or even copper studs, both are stronger then aluminum.
Can you tell me why you are putting loctite or any other chemical on your battery studs? Any substance you put on those battery studs with few exceptions (there are some anti-corrosives that you might be able to use) is going to drastically increase resistance and clobber your battery performance I would think. I have never heard of anyone doing this and, as an engineer, it seems terribly wrong. Maybe you have a good reason but I sure would like to know what it is. In short, as with all expensive endeavors, don't do anything no matter how good it seems until you are 100% certain it is okay.
According to my research, Very little if any current flows via the stainless steel studs. It takes the path of least resistance which is the face of the aluminum terminal. So I focus on minimizing the resistance at the terminal interface. I am using the locktite because it purports to increase the mechanical strength of the thread interface to the stud. I want to avoid any further stripping of soft aluminum threads that I detailed in my previous video.
@@metagrid9453 The resistivity of stainless steel is about 41 times greater than copper and about 26 times greater than aluminum. So if you had a current of 100 amps about 3.7 amps would flow through the the stainless steel and 96.3 through the aluminum if they had the same area. It may not seem like much but to the other batteries it looks like added cell internal resistance. Over time it may or may not cause a problem. Just from a personal standpoint, I would avoid interfering with conductivity/resistance. Also keep in mind that stainless steel is more resistant to corrosion in most cases so, again, over time as aluminum oxide builds up on your battery terminals their resistance will likely grow faster than the stainless steel lugs. Personally, it is not the kind of experiment I would like to run with my expensive batteries until I had talked to a real expert (not me). Remember, even though current prefers to flow through the lowest resistance that does not equate to no current through more resistive paths.
@@metagrid9453 Forgot to mention, rather than locktite, why not just re-tap the holes and get a new stud? You would need a flat bottom tap to reach the bottom of the hole.
I like the information Meta Grid. I am doing 64 cells in a 48 volt configuration. Do anybody know how long of a time and what amps of a charger will it take for a charge . Right now I have a military gen. as an solar array I want to figure out the total run time on batteries and the amount of generator run time to charge this type of battery, I hear it charge faster. Best of luck on your project, and Thank for sharing. Sailorboy
It depends on how many Amps your charger can charge and discharge. Im going to buy the Deye 12k Hybrid inverter that can Charge/discharge with 240A, that is 240x48V=11.5 kW. if your battery is 56kWh it will take aroound 56/11.5 = 4.8 hours (less if you use 80-90% of the battery capacity) of charging. If you have lower amp on your charger you just exchange my 240A to your number to see how many hours it will take you.
Ya I think not but don't you need threads for a helicoil if so I'd just drill it if necessary and tap to the next size or possibly a SAE size I assume they are metric
It looks like he has 32x 280ah 4S8P configuration, making close to 27kw. Unless he has double the batteries, I’m not sure where he got his figures from. Still a massive size 😁
@@CryptoNut82 This system consists of a total of 64 of the eve 280AH cells. They are arranged in paralleled packs of 4 and there are 16 of those packs in series. 280AH X 4 = 1120AH Total X 52 volts = 58,240 or about 58KWH
I can't wait to get my batteries - just ordered last week. I'll be watching your videos again once they arrive. I'm still trying to decide what BMS I'm going to employ.
There are quite a few options for BMS. Just to further cloud the issue and make the decision more difficult, overkill solar just came out with a 16S/48V nominal version of their BMS system for around 130$, depending on options.
Got a link to which supplier you went with for the batteries David?
@@w3bb0y Sure. I got mine as part of a group buy from the DIY Solar Power Forum group: diysolarforum.com/threads/lishen-272ah-thread.12871 Send a PM to Michael B Caro and he will get you a quote. They usually do a group buy every month.
You sure turned the project into a lot of work! I hope it increases your satisfaction with the result.
I am having a lot of fun!
The blue foil will age over the years and establish contact between the aluminum cells. Positive is connected to the aluminum housing. Spacers must be placed between the cells. !!!
Nice attention to detail - same heights, level bus bars :)
Absolutely. Don't want any unseen gaps between the interconnections and the terminals,...
looking into the same LiFePO batteries you recomended thank you!
You bet! They have been working well for us. Will have an update out soon.
The only thing I would add and this has also been mentioned on diysolarforum is that aluminum oxide is not very conductive so wire brushing the terminal tops is the most important step. Perhaps you did that earlier but it forms very quickly so the antiox should be applied after buffing.
Thanks! I did in fact wire brush the tops previously. I also wiped away the oxide dust with 99% Isopropyl alcohol on a paper towel. I then immediately coated the terminals with No-Ox-ID. If I had to do it over again I would have inserted the studs into the threaded holes before applying the No-Ox-ID as some of it got inside the lip of the hole which had to be cleaned out with a qtip before inserting the locktited studs.
keep it coming.excellent.
Thanks!
looking good
Thank you!
Looking good. Can this batteries be charged below freezing?
In general, no.
No !!!!!!!! I wound not charge anything below 32 degrees to be safe. And live a long life.
Don't clean the posts on the cells?
I put my lifepo batteries in parallel as one would do with most batteries and it clobbered the capacity. I lost about 30% compared to what I should have gotten. Differentilal voltages between various parallel groups connected in series went wild to the tune of several hundred millivolts. I thought my batteries were bad but tested them individually and in series and all was fine. Took them out of parallel and just put them in series and got the capacity I expected. Not sure why but you should do some tests first. My guess is that the complex nature of Lithium battery chemistry and the distribution of internal resistance inhibits equal charge sharing between the batteries like we would expect with most things connected in parallel. You might be better off with 4 independent batteries in series with a bms on each and paralleled at the whole battery level. I will be checking that configuration out eventually. Since these batteries take so long to charge it is a very time consuming endeavor to experiment. By the way, you might not expect it but the busbars and cables have a significant resistance compared to the internal resistance of the lifepo batteries. Mine did anyway as they were 1/16 " thick by 3/4 " and 3" long. Therefore, you might want to try and connect the parallel groups with 4 busbars between each group (one off of and to each battery terminal). I saw this recommendation but did not follow it and maybe that also contributed to my problems. Oh, excuse me, I just got a shot of your battery configuration and it looks like you are doing it as recommended. I will be very interested to know if you get the capacity you expect.
I wonder if it would help to have double bus bars between the cells in each parallel group? I have lots of extras...
@@metagrid9453 I think it might help but I am skeptical that it would really solve the problem. Then again, maybe it was just my batteries and/or my setup. I think not though. I calculated that my busbars (1/16 X 3/4 X 3 inch) had a resistance of about 25% of the internal cell resistance. That is assuming that the BMS I used which gives an estimate of internal resistance was correct. That might be a big assumption. In any case, we are stuck with the internal resistance of the cells and they will differ between cells which means we will always get different currents through each cell. If the IR is close enough it might not be a super big deal but, as you probably know, once you get towards the ends of the charge and discharge cycle IR goes nuts pretty quick. I am very interested to see if you experience the same thing if you want to take the time to test it.
A lot of people mess up connecting batteries in parallel, as the obvious way isn't optimal: www.solar-electric.com/lib/wind-sun/Iota_balanced_charging.pdf
@@alharrison3255 Thanks for the article Al. Yes, I am familiar with the problem and had mine connected as shown in figure 3. Although that is not bad, the article says I can do better so good to know. Since I wrote my statements above I did find out that a significant part of the problem was a software bug in my BMS that made it give me inaccurate amp hour measurements. Despite a firmware release, the BMS problem is not fixed yet. Just installed another BMS firmware fix yesterday but have not tested it yet.
Agree 100%. 6 16s batteries with individual BMS’s of different brands. Redundancy.
I realize that most of the contact is not the stud, but since stainless steel is poor conductor had you considered using brass or even copper studs, both are stronger then aluminum.
It is hard to find copper or brass studs.
Found some brass set screws m6 x 20mm on eBay, would that be long enough
Did some more searching and found another source, aliexpress has m6 brass studs in many lengths
The surface area of the terminal post is large enough to pass enough more current than this battery would typically put out.
@@jakealmaguenther4366 I need 25MM
What gauge cable are using on the batteries?
The serial connections between the groups of cells are 4AWG welding cable.
@DIY Projects It is 4AWG. Just checked again.
Can you tell me why you are putting loctite or any other chemical on your battery studs? Any substance you put on those battery studs with few exceptions (there are some anti-corrosives that you might be able to use) is going to drastically increase resistance and clobber your battery performance I would think. I have never heard of anyone doing this and, as an engineer, it seems terribly wrong. Maybe you have a good reason but I sure would like to know what it is. In short, as with all expensive endeavors, don't do anything no matter how good it seems until you are 100% certain it is okay.
According to my research, Very little if any current flows via the stainless steel studs. It takes the path of least resistance which is the face of the aluminum terminal. So I focus on minimizing the resistance at the terminal interface. I am using the locktite because it purports to increase the mechanical strength of the thread interface to the stud. I want to avoid any further stripping of soft aluminum threads that I detailed in my previous video.
@@metagrid9453 The resistivity of stainless steel is about 41 times greater than copper and about 26 times greater than aluminum. So if you had a current of 100 amps about 3.7 amps would flow through the the stainless steel and 96.3 through the aluminum if they had the same area. It may not seem like much but to the other batteries it looks like added cell internal resistance. Over time it may or may not cause a problem. Just from a personal standpoint, I would avoid interfering with conductivity/resistance. Also keep in mind that stainless steel is more resistant to corrosion in most cases so, again, over time as aluminum oxide builds up on your battery terminals their resistance will likely grow faster than the stainless steel lugs. Personally, it is not the kind of experiment I would like to run with my expensive batteries until I had talked to a real expert (not me). Remember, even though current prefers to flow through the lowest resistance that does not equate to no current through more resistive paths.
@@metagrid9453 Forgot to mention, rather than locktite, why not just re-tap the holes and get a new stud? You would need a flat bottom tap to reach the bottom of the hole.
I like the information Meta Grid. I am doing 64 cells in a 48 volt configuration. Do anybody know how long of a time and what amps of a charger will it take for a charge . Right now I have a military gen. as an solar array I want to figure out the total run time on batteries and the amount of generator run time to charge this type of battery, I hear it charge faster. Best of luck on your project, and Thank for sharing. Sailorboy
It depends on how many Amps your charger can charge and discharge. Im going to buy the Deye 12k Hybrid inverter that can Charge/discharge with 240A, that is 240x48V=11.5 kW. if your battery is 56kWh it will take aroound 56/11.5 = 4.8 hours (less if you use 80-90% of the battery capacity) of charging. If you have lower amp on your charger you just exchange my 240A to your number to see how many hours it will take you.
Dang you striped 3 are you going to try an tap them bigger or what
The JB weld did not hold, will be inserting helicoil threads next.
Ya I think not but don't you need threads for a helicoil if so I'd just drill it if necessary and tap to the next size or possibly a SAE size I assume they are metric
@@james10739 I installed Helicoils. Working fine. Torqued to 4NM without issue.
58kW battery for powering a small village
It looks like he has 32x 280ah 4S8P configuration, making close to 27kw. Unless he has double the batteries, I’m not sure where he got his figures from. Still a massive size 😁
@@CryptoNut82 This system consists of a total of 64 of the eve 280AH cells. They are arranged in paralleled packs of 4 and there are 16 of those packs in series. 280AH X 4 = 1120AH Total X 52 volts = 58,240 or about 58KWH
Pretty much!
@@CryptoNut82 each cell is 3.2V at 280Ah multiply by 64 to give u 57344 watts
@@metagrid9453 well that explains it, you have 64 batteries, only saw around 32 so I obviously got half the KWs hehe
Doctor squash saids it your balls we're talken about man do it for Dan!!!???