Got some batteries, figuring out what to do with them

Festus

Festus

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Aug 26, 2022
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So I decided to try my hand at building a DIY powerwall after coming into possession of a lot of ebike batteries. This place seems to be a great wealth of information to start my next big project.

On getting the ball rolling on this project... I've got the batteries covered, but I was thinking if anyone here wanted to barter for equipment or give advice on where to sell excess batteries, that would be great start for me. I'll be researching info on batteries, BMS, inverters, ect. in the meantime trying to figure out what the hell I'm doing.

Cheers
 
If all the ebike batteries are the same model and capacity , take photos of the batteries, the bms used, the cells clearly showing the brand of cell used,the model of cell used. and post them in the marketplace https://secondlifestorage.com/index.php?forums/marketplace-selling-commercial.20/ , listing how much you want for them if you will ship them or local sale only full guidelines on what is needed in the sale post is located https://secondlifestorage.com/index.php?threads/marketplace-guidelines.2163/
Later floyd
 
Perfect! Thanks Floyd. Did not know there was a marketplace on this site.
 
Sounds like you have an ideal start into the addictionhobby :)

It sounds like you should start in the FAQ area and that will give you a nice foundation of the basics. I also recommend you check out a few threads.
18650 Harvesting Flow Charts; https://secondlifestorage.com/index.php?threads/18650-harvesting-flow-charts.9714/#post-66496
Internal Resistance(IR) Metering is HIGHLY recommended and saves loads of time and headache; https://secondlifestorage.com/index.php?threads/ir-meter-recommendations.10361/
BMS I recommend is the DIY BMS for powerwall type applications and the Daly ones are pretty good for more portable solutions just make sure to only use them at 50% of the rated capacity they advertise which is a bunch of BS; https://secondlifestorage.com/index...building-the-diybms-by-stuart-pittaway.11871/
And if you want to really geek out then any of Wolfs posts like this one; https://secondlifestorage.com/index.php?threads/the-passion-of-the-li-ion-18650.11456/

Have fun!
 
Thanks cak, that gives me a lot to read. I'll just pester you with one quick question before continuing to digest all this information. On the BMS topic, will any of them (Batrium?) allow for charging with individual specifications of battery packs, or do you have to stick to one type of 18650 for every battery pack. That's hard to put into words. To clarify, I don't want to mix and match 18650 within a single battery pack.

I'd like to list some of the batteries I have in the market place to fund my build, but some have better specs than others and I have more of some types than other types. This seems like a topic that would be easy to find, but the information I found was related to mixing types of 18650 within a single battery. I'll end up keeping the 18650-29E, which I have the most of and sell the rest if this is the case.

Thanks again for the intro!
 
Festus said:
So I decided to try my hand at building a DIY powerwall after coming into possession of a lot of ebike batteries. This place seems to be a great wealth of information to start my next big project.

On getting the ball rolling on this project... I've got the batteries covered, but I was thinking if anyone here wanted to barter for equipment or give advice on where to sell excess batteries, that would be great start for me. I'll be researching info on batteries, BMS, inverters, ect. in the meantime trying to figure out what the hell I'm doing.

Cheers
Click to expand...
...excess batteries (I assume you mean cells)???
I have heard of this mythical creature, but was quite confident that it did not really exist!
You must be planning on one gigantic powerwall if you are confident you have "excess" cells!:D
Mine has 3,360 cells (that is how many AFTER processing), OffGridInTheCity has about million give or take a few, and Wolf is trying to catch him.
Selling cells should not be a problem, most have trouble finding enough.
Welcome to the addiction, I wouldn't sell any cells until you are sure you have ALL the cells you will need, plus enough to build another battery for the pack so you can switch it out for repairs.
A bigger powerwall is better, to a point. The bigger it is, the shallower the cycles for the same amount of power used, extends the life of the cells.
 
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Dr. Dickie said:
...excess batteries (I assume you mean cells)???
I have heard of this mythical creature, but was quite confident that it did not really exist!
You must be planning on one gigantic powerwall if you are confident you have "excess" cells!:D
Mine has 3,360 cells (that is how many AFTER processing), OffGridInTheCity has about million give or take a few, and Wolf is trying to catch him.
Selling cells should not be a problem, most have trouble finding enough.
Welcome to the addiction, I wouldn't sell any cells until you are sure you have ALL the cells you will need, plus enough to build another battery for the pack so you can switch it out for repairs.
A bigger powerwall is better, to a point. The bigger it is, the shallower the cycles for the same amount of power used, extends the life of the cells.
Click to expand...
Damn it! Based on what you said about excess cells, I went to double check the ebike batteries. I had assumed that I could sell all these red ebike batteries because I had more of a different type (black 36V), but I found out this morning that the quality and type of cells in those other batteries is different. Until all of them are checked, I don't know, I might actually end up with more uniform cells from these red batteries, which is around 72 batteries with 52 cells in each = 3700.

Anyway, that's why I came here. That's good advice. Thanks!

The red batteries have LG18650M26 (lightly used), 36V black batteries so far have both samsung 29E and 35E cells, and 48V black batteries have LG18650MH1 cells. The specs on these are pretty different. Looking at the repackr spreadsheet, it seems the capacity and resistance need to be similar for each pack?
 
Festus said:
72 batteries with 52 cells in each = 3700
Click to expand...
Depending on the condition of the EV batteries you have you are likely to reject 5-70% of the cells through testing. As an example there are a bunch of Ebike batteries that i got from battery clearing house that were obviously not used at all and so was able to repurpose 98% of them. and on the other side of the spectrum tool batteries I have taken apart I maybe get 20% that are usable(many are damaged/rusty) and those often don't test anywhere close to new.

As to matching cell models it helps but is not the end all since how degraded the cells are can also lead to significant variability as you select your pack cells.
Festus said:
On the BMS topic, will any of them (Batrium?) allow for charging with individual specifications of battery packs, or do you have to stick to one type of 18650 for every battery pack. That's hard to put into words. To clarify, I don't want to mix and match 18650 within a single battery pack.
Click to expand...
I am not sure I totally understand your question but a BMS does not control charging. A BMS is simply a safety pack monitoring device that can ideally turn the pack off if things are off. The one function most BMS do beyond that is that when one cell(s) series pack gets to a max set voltage before the others the BMS will apply a slight load via a resistor to hold that cell down and help it get back in balance. With well designed and balanced packs the BMS should be doing little to non of this balancing and a BMS is never a substitute for a well designed pack as the resistors are generally not enough to keep poorly balanced cell(s). [as a note in this context I am referring to a "cell" as one or more paralleled cells that are functioning as one "block" of cells being monitored by the BMS. You can have these "blocks" be as small(one cell) or large as you want but logistical concerns often lead to similarly sized "blocks" 80-100 18650 cells is common.]
 
That 72 number is down from a starting point of 76. Two packs had no charge so I just tossed them, two are questionable due to charge being below 2.5V. Every pack I've tested that had a decent starting voltage has been "good" so far. I ordered a resistance meter based on your linked sources. How degraded they are hasn't been variable so far as of testing about 10% of the EV batteries. We'll see if it keeps up.

Yeah I wasn't sure how to word my question. I looked at the repakr spreadsheet and I see the packs need to be close but the battery type doesn't matter, with caveat of not mixing some chemistries. I was wondering if the packs could have a mixed capacity or resistance (not within the pack or individual 18650s), but I think I know the answer to that. You answered one of my other questions about how large of a "block" people went with, with 80-100 cells.

Thank you! This has been a huge help.
 
cak said:
Sounds like you have an ideal start into the addictionhobby :)

It sounds like you should start in the FAQ area and that will give you a nice foundation of the basics. I also recommend you check out a few threads.
18650 Harvesting Flow Charts; https://secondlifestorage.com/index.php?threads/18650-harvesting-flow-charts.9714/#post-66496
Internal Resistance(IR) Metering is HIGHLY recommended and saves loads of time and headache; https://secondlifestorage.com/index.php?threads/ir-meter-recommendations.10361/
BMS I recommend is the DIY BMS for powerwall type applications and the Daly ones are pretty good for more portable solutions just make sure to only use them at 50% of the rated capacity they advertise which is a bunch of BS; https://secondlifestorage.com/index...building-the-diybms-by-stuart-pittaway.11871/
And if you want to really geek out then any of Wolfs posts like this one; https://secondlifestorage.com/index.php?threads/the-passion-of-the-li-ion-18650.11456/

Have fun!
Click to expand...
Looks like I'll be testing batteries for a while. I've ordered an additional OPUS to get through this a bit quicker. In the meantime I've been looking into inverters, BMSs and solar. One question I had on your link on the DIYBMS, it looks like a lot of work to set up- why do you recommend that one over Batrium? I get the DIY aspect, but in the end, it gets a bit time prohibitive if you DIY everything.

OK, so I looked a bit more at the DIYBMS and the building isn't too bad, but still will take some effort. I guess it's not that much more effort than the Batrium set up? I still do wonder about the benefits of each, which I'm sure that's somewhere on here.
 
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Festus said:
Looks like I'll be testing batteries for a while. I've ordered an additional OPUS to get through this a bit quicker. In the meantime I've been looking into inverters, BMSs and solar. One question I had on your link on the DIYBMS, it looks like a lot of work to set up- why do you recommend that one over Batrium? I get the DIY aspect, but in the end, it gets a bit time prohibitive if you DIY everything.

OK, so I looked a bit more at the DIYBMS and the building isn't too bad, but still will take some effort. I guess it's not that much more effort than the Batrium set up? I still do wonder about the benefits of each, which I'm sure that's somewhere on here.
Click to expand...
Cost is a big advantage of the DIY BMS over the Batrium. Other than the parts sourcing in this chip shortage era I found the DIY BMS to be pretty easy and a great learning DIY project. There were a few tools worth getting but they are also super great for other projects, SMD reflow heatgun, etc.
 
cak said:
There were a few tools.... SMD reflow
Click to expand...
Which now, if getting from JLCPCB or PCBWay, they offer SMD reflow options for free, or really cheap. Only thing to add afterwards would be the through hole components.
So even the assembly is a lot easier than it used to be.
Though still recommend the tools for other projects as well ;)
 
cak said:
Cost is a big advantage of the DIY BMS over the Batrium. Other than the parts sourcing in this chip shortage era I found the DIY BMS to be pretty easy and a great learning DIY project. There were a few tools worth getting but they are also super great for other projects, SMD reflow heatgun, etc.
Click to expand...
I had to look up what a SMD reflow heatgun was. I've been reading wolf's post on his build and watching the diybms videos. I'm going to give it a shot, although I'd prefer not to do the soldering myself on small components if there are alternatives. It will be a while until all the battery testing is done anyway. It will give me more time to figure things out and source the components.
 
Festus said:
I'd prefer not to do the soldering myself on small components if there are alternatives.
Click to expand...
0603 components are 'ok' to solder. Anything bigger is pretty easy to deal with. The buggers to work with are the 0402 and smaller are the pitas. 0603 can be an issue if you don't have steady hands. At least with those, you can hold them in place pretty easily with tweezers.

But generally speaking, yeah, have someone else do it that can do a bunch of them at once quickly and 99+% accurate :p
 
Korishan said:
0603 components are 'ok' to solder. Anything bigger is pretty easy to deal with. The buggers to work with are the 0402 and smaller are the pitas. 0603 can be an issue if you don't have steady hands. At least with those, you can hold them in place pretty easily with tweezers.

But generally speaking, yeah, have someone else do it that can do a bunch of them at once quickly and 99+% accurate :p
Click to expand...
Good to know on the small components. I really appreciate the willingness of folks here to give out advice. This is somewhat of a big undertaking. I've got some skills so it's not all Greek to me, but I can tell this is going to be challenging. Eventually I'd like to do something similar to OffGridInTheCity. Unfortunately, Alabama is the worst place to be doing this. The power company charges a "fee" on people generating their own power to discourage competition. There are added complications on non-technical related topics I wouldn't bore people here about :( so it's nice to have this community's help on the technical side. In comparison, my SIL is in Florida and they are adopting solar fast in her neighborhood. I see panels all over the place when I'm down there and pretty much never see them here.
 
Festus said:
I really appreciate the willingness of folks here to give out advice
Click to expand...
That's what we're here for :)

Festus said:
The power company charges a "fee" on people generating their own power to discourage competition.
Click to expand...
This is where having a hybrid inverter with zero backfeeding comes in handy. You can offset your power consumption from the grid but never have it set to 0 incoming that way you still buy a teeny tiny amount of power. Then if the grid goes offline, the Hybrid will switch fully to battery like a UPS.

I'm in N.Central Fl. There's a lot of panels going up around here too. At least here most of the power companies are actually trying to help ppl get more panels up. They even will co-sign with the loans to get them installed (at least Clay Electric does). Crazy how different states are run differently with the exact same stuff. :rolleyes:
 
Korishan said:
This is where having a hybrid inverter with zero backfeeding comes in handy. You can offset your power consumption from the grid but never have it set to 0 incoming that way you still buy a teeny tiny amount of power. Then if the grid goes offline, the Hybrid will switch fully to battery like a UPS.
Click to expand...
This is the kind of info I need. Hopefully decreasing my power consumption, while still purchasing a small amount of power won't raise any red flags. Alabama has more coal and gas than Florida, but about the same amount of sun. Entrenched industries buying off the public service commission has pretty much allowed Alabama power get away with this kind of crap, but it's not sustainable. They are going to have to go up on rates. It's sad to see them trying to greenwash the stuff they are doing by selling RECs, (renewable energy certificates) rather than just not charging their fees.
 
Dr. Dickie said:
...excess batteries (I assume you mean cells)???
I have heard of this mythical creature, but was quite confident that it did not really exist!
You must be planning on one gigantic powerwall if you are confident you have "excess" cells!:D
Mine has 3,360 cells (that is how many AFTER processing), OffGridInTheCity has about million give or take a few, and Wolf is trying to catch him.
Selling cells should not be a problem, most have trouble finding enough.
Welcome to the addiction, I wouldn't sell any cells until you are sure you have ALL the cells you will need, plus enough to build another battery for the pack so you can switch it out for repairs.
A bigger powerwall is better, to a point. The bigger it is, the shallower the cycles for the same amount of power used, extends the life of the cells.
Click to expand...
Hey Doc. You were spot on with not selling these. I'm starting to find more and more bad battery packs. I unfortunately am an idiot and keep cutting myself trying to get these stupid packs opened up to get to the cells. These things aren't easy to get into. I'm starting to get a system worked out, but too many beers, overconfidence, and utility knives need to be taken out of the equation.

I thought I had checked all the packs for voltage and that they would all be good because of that. Maybe I missed some, but I wrote down the voltage on the outside of the pack on some, and when I opened them up they had a bunch of bad cells. Guess that voltage reading isn't really representative of the health of the whole pack.
 
Get yourself a pair of working gloves. They work wonders with keeping cuts from your fingers away.
 
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