Discover AES LiFePO4 Battery with one dead cell- Is it possible to repair?

208stephen said:

once they sit at 0.0V for awhile they're not recoverable

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Yes, more or less not worth it and dangerous to use even if everything looks ok.

208stephen said:

So I would replace the Discover BMS with the JK?

I was thinking that I would replace all 15 cells of the group

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These are 2 good options. If this battery is alone, with no other batteries in parallel, you could buy the JK BMS and wire it up yourself. This might not be too easy. You would need to either find the balance cables and correctly splice them to the new BMS. Any mess up here could ruin the BMS. You need to know what you are doing. Please do your homework and wear safety glasses any time your are messing with any battery system.

Buying and spot welding a replacement would probably be easier. The hard part of this is finding a good spot welder. It would not be worth it to me pay $200 for a welder and $300 for 26650's. Also it might not be easy to find a shop to help. I doubt that every Batteries Plus shop has a spot welder.

I would buy the JK BMS. Just my opinion. It depends on how much money you want to spend to make the battery not more ewaste and preserve your investment.

ScrotusGobbleBottom said:

Yes, more or less not worth it and dangerous to use even if everything looks ok.



These are 2 good options. If this battery is alone, with no other batteries in parallel, you could buy the JK BMS and wire it up yourself. This might not be too easy. You would need to either find the balance cables and correctly splice them to the new BMS. Any mess up here could ruin the BMS. You need to know what you are doing. Please do your homework and wear safety glasses any time your are messing with any battery system.

Buying and spot welding a replacement would probably be easier. The hard part of this is finding a good spot welder. It would not be worth it to me pay $200 for a welder and $300 for 26650's. Also it might not be easy to find a shop to help. I doubt that every Batteries Plus shop has a spot welder.

I would buy the JK BMS. Just my opinion. It depends on how much money you want to spend to make the battery not more ewaste and preserve your investment.

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I have 6 of these batteries currently and ideally would like to ad this battery if I can repair it. I have a Lynk 2 that allows me to monitor the batteries and I'm assuming would not interface with the JK BMS.

208stephen said:

would not interface with the JK BMS.

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correct. most likely not compatible.

ScrotusGobbleBottom said:

correct. most likely not compatible.

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Probably best bet is to find an EV battery repair shop that has the necessary spot welder and experience with larger battery packs. This battery would probably be quite easy for them to figure out. Must be some automotive EV shops in your area?

You might reach out to Discover and request purchasing the specific battery part that you need now that you have figured it out. That way their liability might not be as much.

Could you arrange to ship the battery back to them for them to repair?

I'm a bit concerned about Discover's reluctance to support their products given that I just ordered a significant number of their batteries.

Send me a PM and I can discuss further options with you.

It looks like I'm running out of options so I'm leaning towards going into the unit and replacing all 15 cells with new ones. I know that they are 26650 cells, 3.2V, 3.8aH. Does anybody out there know what brand cells that Discover uses in their batteries? How important is it to use the same brand?

Any advice on breaking spot welds?

Any advice on a reasonably priced spot welder?

It is relatively easy to make a spot welder from an old microwave magnetron transformer. There are several Youtube videos!

You can also make a spot welder attachment for a conventional welder.

An an old microwave magnetron transformer can kill you if you touch the wrong thing even while unplugged. Be careful with this idea.

The Youtube videos show you how to take the windings off the transformer in order to make a spot welder. The idea is to make it into a low voltage high current power supply which makes the transformer safe to use. Do be careful though!

I finally made some time to get into this battery. Today I removed the busbars for the bad cell. The busbars themselves are in good shape but the metal tabs that were spot-welded to the batteries didn't fare so well.

Now that the individual cells are isolated is there any way that I can test for a bad cell(s) without opening up the plastic casing?
Or, since they all read 0.00 volts, are they all bad and in need of replacing? I have found a warrantied Discover Battery that I may be able to recycle good cells from.

The busbars have thin sheets of metal spot-welded to them with 2 tabs for spot-welding to the batteries (see photo below). Are these strips a proprietary Discover item or are they a standard item that's available and that could be replaced?

If they're not available, and I decide to replace all the cells, what would be the best way to spot-weld the batteries to the busbar?

I got the case open this morning and removed all 15 batteries from the bad string. It's pretty clear that one of the cells was defective (shorted?). Looks like it got hot and started leaking. Here are some pictures of the one damaged cell next to an intact cell.

And here's a picture of the only marking on these cells. Anybody have any idea about what brand they are or how I might find out.
I've asked Discover directly, but apparently it's "top secret". WTF?

I've done what you're trying to do. This was with a discover AES 6.4 KW battery I think. The design of that battery something like 24 cells in parallel then 16 in series. The connections between cells are not bus bars but were circuit board material I guess with a lot of conductive material in it. There are holes in these boards and the cells had male and female screws/threads on them so you could rotate the cell through the hole to lock with the next cell. I pulled out all the cells and tested every single one of them I removed about eight or nine cells which showed a zero voltage and then reconfigured the battery with fewer cells in parallel but the same number of parallel groups in series. It was not difficult but it was a lot of work. The trickiest part was removing and reinstalling the outer case. I put the battery upside down on a sheet of thick honeycomb cardboard then lifted with a forklift on straps that were wrapped on the handles of the outer case of the battery. I had to do a little jiggling to get the inner works to slide out of the outer case. There was an arc when I did this but it was momentary and did not seem to affect the battery later. When I put the reassembled in our works back into the battery case I wrapped the edges of the outer case with a non conductive tape to help prevent arcing. After I put the battery together I noticed that it seemed to think it was discharging all the time this was a problem with the internal shunt being tightened too much. I loosened the nuts a little bit and then it began reading current properly. I never really used this battery it was more for fun and as far as I know it's still working. I did all this work at a solar shop I was working at the time they were very understanding. These are cool batteries but I don't like the arrangement of many many parallel cells without fusing. I forget the exact number on the side of the cell but I recall them being 5,000 milliamp hours possibly 5,500 milliamp hours. I did find replacement cells on Amazon but never ordered them because there was no need.

Thanks for your reply. It sounds like their bigger batteries have a different kind of construction. Threaded terminals would be much easier to deal with. For me to put my battery back together I'll have to buy a spot welder and learn how to use it.

The cells that had 0 volts you threw away or were you able to recharge and use them? It's interesting that the defective cells didn't take the others down. Were the 8 or 9 bad cells all in the same string of 24?

I've only surgically removed one string of 15 cells from a "panel" that has 4 strings total. There are 4 "panels" in total and all the rest of the cells are holding a resting voltage of 3.32-3.5V.

208stephen said:

Thanks for your reply. It sounds like their bigger batteries have a different kind of construction. Threaded terminals would be much easier to deal with. For me to put my battery back together I'll have to buy a spot welder and learn how to use it.

The cells that had 0 volts you threw away or were you able to recharge and use them? It's interesting that the defective cells didn't take the others down. Were the 8 or 9 bad cells all in the same string of 24?

I've only surgically removed one string of 15 cells from a "panel" that has 4 strings total. There are 4 "panels" in total and all the rest of the cells are holding a resting voltage

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I removed the zero volt cells and did not try to charge them again. there was some leaking electrolyte in the case like a brown fluid that smelled incredibly bad. The zero volt cells weren't all in the same Parallel Group but they were in the same volumetric area. Yeah I don't recall that the zero volt cells brought the other ones down but the battery had been brought in because it would come up to voltage but then go to zero when a load was applied. Discover warrantied that battery and told the shop I worked for to dispose of it responsibly. I figured the most responsible thing was to recover as much energy storage capacity as possible. If I had to guess I would say that the cells were 32550 sized but I don't recall it was several years ago.

underdog5004 said:

I removed the zero volt cells and did not try to charge them again. there was some leaking electrolyte in the case like a brown fluid that smelled incredibly bad. The zero volt cells weren't all in the same Parallel Group but they were in the same volumetric area. Yeah I don't recall that the zero volt cells brought the other ones down but the battery had been brought in because it would come up to voltage but then go to zero when a load was applied. Discover warrantied that battery and told the shop I worked for to dispose of it responsibly. I figured the most responsible thing was to recover as much energy storage capacity as possible. If I had to guess I would say that the cells were 32550 sized but I don't recall it was several years ago.

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Also as I recall I had to take out a few good cells as well as all the bad ones I found so that each Parallel Group had the same number of cells in it. In my mind the smaller 5 amp hour cells aren't worth working with when you can get larger much larger Prismatic cells at a relatively low price. The problem with using multiple low capacity cells is that the hardware overhead grows so you end up spending as much if not more than if you had just used fewer larger capacity cells.