Do I really need a BMS To charge or discharge 12s 3v 20AH cells

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sangesf
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Joined: 11/10/2008
Points: 142

I purchased 50 3.3v 20AH cells from someone online and wanted to build several 36v 20AH packs.
Do I need a BMS since there's no parallel configuration involved?

P.S. I know that some or most of them are probably useless or low amped but I only paid $100 for em.
If I can get even one 36v pack out of them, I'll be happy

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Spaceangel
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Joined: 07/15/2009
Points: 497
Re: Do I really need a BMS To charge or discharge 12s 3v ...

Try hooking them up and charging them then try a discharge. Do it a few times and check every cell. Both on charging and discharging. I notice on using NPX-80 Pb cells if they are the same batch and run numbers they are balanced both charge and discharge but my Yellow Thunder Sky Cells are mostly balanced but not as close as my Gel Cells. If you got a good price it is well worth experimenting with some cells. My new 48 volt LiFePO4 pack from V power has a BMS and I won't remove it for some one designed it and why mess with some ones Engineering.
Lithium technology seem to be fairly New and still evolving so I feel it is best to go with the flow. Even though a good BMS is fairly expensive.
Rusty

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eva-michael
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Joined: 04/12/2010
Points: 22
Re: Do I really need a BMS To charge or discharge 12s 3v ...

BMS is a system which balance the lithium battery pack. But they have a certain range of its balance function.
According to our experience, if these cells are different in voltage. They are very difficult to be made as a pack since their different internal resistances will make them charge and discharge differently.
BMS is a system to keep cells consistent. That's what make cells as a real pack.

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