Best Option for 12V 200A BMS?

[John Frum]

Question on this: I have 8 cells wanting to make what you're talking about. But how would I actually parallel them? Are you paralleling the BMSs too? Or are you just creating the 4S packs, both with individual BMSs and then connecting Pack #1 pos terminal to Pack #2 pos terminal (and same with the negs?)

I am suggesting 2 discrete batteries each with its own bms.
The general topology of the systems that we make is...
all the core components are in parallel.

 

[Just John]

Whats wrong with something like this?

Victron Battery Management System BMS 12/200 BMS012201000

Victron Battery Management System BMS 12/200 BMS012201000 protects the alternator (and wiring), and supplies up to 200A in any DC load.

invertersrus.com

I could do 150A also. I really just want the system to be capable of 300A for a short period of time.

We think of a BMS as a device that monitors individual cell voltages, apparently Victron sells Lithium batteries that have the monitoring built into the battery and communicate to this device. With high cell disconnect set at 4.2v, it is not using LiFePO4 cells.

 

[Just John]

What Joey said while I was typing. Here is one BMS; https://www.electriccarpartscompany.com/12V-4S-200A-EV-Lithium-LiFePO4-BMS-Battery-Management-System

That is a Daly BMS, and their 200 amp models have 4 gauge wiring. I would buy their 250 amp model just to step up to the 2 gauge wiring.

Probably cheaper to order directly from Daly.

 

[qtturner1]

Hi all, I have a functional question regarding a setup just like this. With two independent batteries each with their own bms, wired in parallel, what happens if a situation occurs where just one BMS is tripped/disconnected? Will the two batteries then eventually have different voltages? Will the BMS that shut off re-enable, causing an issue with the two batteries being different voltages? Seems like a situation like this would ideally have the bms's talking to each other, so if one trips the other also shuts off. Not sure if this is realistic, I'm sure that this methodology is used quite commonly. Just trying to learn ?

 

[John Frum]

Hi all, I have a functional question regarding a setup just like this. With two independent batteries each with their own bms, wired in parallel, what happens if a situation occurs where just one BMS is tripped/disconnected? Will the two batteries then eventually have different voltages? Will the BMS that shut off re-enable, causing an issue with the two batteries being different voltages? Seems like a situation like this would ideally have the bms's talking to each other, so if one trips the other also shuts off. Not sure if this is realistic, I'm sure that this methodology is used quite commonly. Just trying to learn ?

You would have to configure the reconnect triggers to avoid a death spiral.
Probably meaning manual intervention to put a tripped battery back in service.