Best BMS for new 16S build w/ heater options?

[WaOffGrid]

Hello! I am building two new 280 amp hour batteries @ 48 volts. A couple questions from a new battery builder:

- regarding long term reliability, what is the consensus on "b" vs "a" batteries-- are they worth it?

- what is the best BMS for providing heating capabilities with documentation? Is it better to power the heating pads directly from the BMS or using some sort of a relay?

- finally, is it better to have two separate 16S batteries or one 2P16S battery w/ two (or one?) BMS? Tradeoffs?

Thank you in advance!

 

[sunshine_eggo]

Hello! I am building two new 280 amp hour batteries @ 48 volts. A couple questions from a new battery builder:

- regarding long term reliability, what is the consensus on "b" vs "a" batteries-- are they worth it?

No such thing as "a". It's a term created by the gray market sellers. They are either "EV grade" meeting all datasheet requirements, or they don't. EVE does the courtesy of indicating a "B" in the QR code. That doesn't mean a re-seller won't sand off the old code and laser on a new.

Generally speaking "B" grade cells seem to meet 90-95% of rated capacity, and meet or exceed Internal resistance and self-discharge requirements.

- what is the best BMS for providing heating capabilities with documentation? Is it better to power the heating pads directly from the BMS or using some sort of a relay?

No idea on heated options. I have a personal opinion based on the posts on this website that DALY should be avoided.

- finally, is it better to have two separate 16S batteries or one 2P16S battery w/ two (or one?) BMS? Tradeoffs?

Depends:

2P16S:
Limited to the output of one BMS
BMS failure = no battery
Single cell failure can take out it's mate.
Single cell failure can be masked by its mate. Can result in a significant delay in determining which cell has failed.
Single cell failure requires that battery must e broken down and reassembled in a working configuration to get battery power restored.

16S2P
Increased cost due to second BMS
Limited to the output of 90% of 2X the BMS rating, e.g., 2X 100A BMS could be counted on (100A + 100A) * 90% = 180%
BMS failure = still have one battery you can work with.
Single cell failure is readily obvious, and battery can be taken offline quickly and you can run on a single battery while you plan for cell replacement.

 

[WaOffGrid]

Great! Thank you for your input sunshine_eggo. Sounds like 16S2P is the way to go.


RE the BMS for heat ... it seems that there are options for JBD, JK, and Sepplos (Apexium?) and that you need to get the correct designation to have the heater feature activated. There is a dearth of information on this particular feature across most of the BMS documentations I have reviewed. Does anyone have a simple package recommendation where some heating pads are directly wired to the BMS? Or at least a configuration that seems to work well? Thanks for the heads up on Daly.

 

[sunshine_eggo]

The three listed seem to be popular and reliable. I personally have a few JBD that I'm happy with - no heat though.

My next will likely be JK due to the ability to use different cell counts (a single BMS model can be used for multiple cell counts - no need to buy 4S or 8S specifically) and active balancing.