Are these even safe or legal?

wayneb

New Member
Joined
Apr 17, 2022
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4
I friend gave these to me as he could not connect 2 of them in parallel as per manufacturer specs, i was curious as to why so i pulled one apart. This is what was inside, i have never seen Lipo flat packs in a 12v battery before. Is this common? is it dangerous?
20220418_160827.jpg
 

Wjm1964

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Feb 4, 2022
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They are just pouch cells, common in some battery brands like kepworth etc. They are fine.
 

wayneb

New Member
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Apr 17, 2022
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4
They are just pouch cells, common in some battery brands like kepworth etc. They are fine.
So in theory i could just take the others out, continue the series and use a 8s bms as opposed to the two 4s bms's that are in them at the moment?
 

Don B. Cilly

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Aug 24, 2021
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Mallorca ES
No, they don't. I mean, they do if you connect paralleled cells in series, but not seried cells in parallel.
But still, you have 8 cells. You want to put them all in series for ~24V, right?
With an 8s BMS.

All I'm saying, is there any need to take any "out"? Just connect them in series where they are, add the BMS and you have your 24V battery.
Or am I missing something?
-
 

740GLE

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What were the voltages of the two batteries you were attempting to parallel? Maybe they were so far apart the BMS said no.
 

OffGridInTheCity

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May 23, 2021
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Absolutely you can take them apart and re-arrange in XsYp. You need to determine if their lithium-ion - 7s (24v), 14s (48v) or LifePo4 - 4s (12v), 8s (24v), 16s (48v) but they will be one or the other and you can build your battery, attach a BMS, and charge accordingly.

I'd recommend a standard test process - e.g. charge fully (use an OPUS w/extender wires or iCharger X8 or something) and discharge to measure capacity. Arrange the pouches (distribute them) in XsYp as you would 18650 cells so the capacities are evenly spread. Maybe most of the pouches will be 85% original capacity or better (keepers) and a few <60% (discard) or something like that. Let them sit for a few weeks to confirm no self-discharge. If you can find IR specs, test for IR and discard any outliers. Then assemble :)

Since they are pouch, a firm container or gentle compression to hold them from swelling is recommended.

Of course be careful as you would with any cell or pouch or brick :)
 
Last edited:

RCinFLA

Photon Sorcerer
Joined
Jun 21, 2020
Messages
1,779
The positive tabs are likely aluminum. Now that you disconnected them you will have aluminum oxide build up on positive tabs. This will degrade their connection resistance. Before reconnecting clean with 50/50% white vinegar/water then clean and dry with 91% alcohol.

The negative tabs are likely nickel-plated copper. Just clean and dry them with 91% alcohol.

Keep dirty, salty fingers off of cleaned tab surfaces.
 
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