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Why do you guys think that some chinese made cells are going to be any safer than a battery custom made to use in a car in a huge variety of conditions while being rattled about and have comparatively huge loads put into and taken out of it?

Something designed for a car is massively over specced for use as a battery bank in a boat!

As far as BMS's are concerned the ratio of batteries saved by BMS's to batteries killed by BMS's appears to be about 1:20

I would NOT have some low volume DIY BMS protecting my system - the Automotive ones would be OK

But otherwise you only need to know if a cell has failed - and a "Battbridge"
will do that for you

6,489 Posts
No one is talking about using the original vehicles BMS, they are only suitable for the EV parameters.

Chopping up salvaged auto packs then re-assembing into small lower voltage blocks is what you apparently don't realize you're talking about.

And doing that requires a much more stringent custom BMS in any case, and that's a much greater challenge than the simple LVD / OVD needed to protect standard prismatics.

The main point is, these non-LFP chemistries are inherently more dangerous.

The biggest buyers of LFP prismatics are military, in use cases much bouncier than civilian EVs.

China is irrelevant, it is the brand and sales channel that needs to be trustworthy.

I don't see that in most eBay sellers and junkyards myself.
BMS's cause battery fires - most failures have been caused by the BMS partially discharging one cell

- without a BMS as long as you know that no cells have failed you are much safer than with some shoddy non OEM BMS

And yes I do know about
"Chopping up salvaged auto packs then re-assembling into small lower voltage blocks "
As I have a lower voltage pack in my car


Prismatic LFP have a much much higher failure rate than OEM cells - almost everybody who has used them has experienced at least one cell failure

NON OEM BMS's - have a similar high failure rate

OEM cells have a very low failure rate AND if you don't have a stupid BMS unbalancing them they won't go out of balance!

Battery fires are caused when a cell fails completely and you then charge the battery to the normal voltage - leading to n overcharge

If you have a BattBridge it will give warning if a cell has failed - that is all that you need to avoid problem
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