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Charge Only BMS wiring advice

due to lack of fortune, it seems I have ended up a BMS that is rated at 30A in a pre-built battery pack
GZLS new36v v1.2 13710343220 BMS

I’d like to utilize more current of the 30Q battery (10S3P @15A =45A) say conservatively 40A
the wiring diagram for this BMS looks something like this:

My thinking, to bypass the Discharge section of this BMS, making it a charge only BMS I’d simply chop the P- BMS connection and route it directly to the discharge, something like this:

add a fuse to the charge port, and a loop key disconnect on the negative lead. does this look, or sound cray-cray? also since this is a 10S pack and only a 10 lead balance connector the BMS needs a negative lead source so I’ll keep a negative source connected to B-

All comments and criticism welcome.


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blasphemy I tell you simply blasphemy and a general misuse of condiments in general!


This looks correct to me, I really don’t like the way that you drew the loop key being so close the Discharge it implies that you’re using the discharge but we can clearly see that that is not the case.

There really isnt much more that I can really add here, the fuse may or may not be necessary for charging rather discharging IMO, but adding a fuse surely wouldn’t hurt anything.

The Balance Harness looks correct based on the image(of the bms) you provided, you should have 10 Positive connections (one for each of the Harness Leads) and one Negative connection which can/will be shared (as you have it illustrated) with discharge.

Im sure other will chime in, but from a glance this appears about the same way (Sans fuse) i have my 10s wired.


Your diagram looks fine :+1:
Bypassing discharge is fairly common BMS practice AFAIK.

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Yes, this looks great – if you don’t have any accessories.

If running lights or anything else not related to drivetrain function, I would do this

example with lights/accessories circuit:

this way if there is a battery issue, your lights will turn off – consider this a warning from the BMS to pull over and pull the loopkey as soon as it’s safe to do so! :wink: (but it’s not gonna cut your brakes)

I also added these diagrams to the loopkey thread, thank you :slight_smile:


@b264 That’s a solid recommendation. I never considered using a low amp bms like that. :ok_hand: