Look key taken OUT, battery still on

I feel like I’m overseeing something very obvious, hopefully you guys can help solve this problem for me. I created this battery/setup myself after a while of learning how to do so.

I just got my board up and running but I noticed the 4.2 VESC blue power light is always on regardless if my loop key is connected or not. I made a 10s4p and got a 30A BMS that I’m bypassing. I connected B- directly to the BMS, and have the negative load connected directly to that B- (ignoring P-).

I knew something was wrong when I got off the board, TOOK OUT the loop key, then put some throttle on the remote and watched my board take off without me. :rofl: :rofl: :rofl:

I tried to share a picture from my point of view of the flow of current to show why Im confused about the situation. (In the picture the load negative and battery negative are soldered on the B-) Was it something to do with me connecting load negative and battery negative directly to the BMS or something?

All help is appreciated :slight_smile:

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Yep, I believe the issue is this: even though you’ve unplugged the loop key, the negative of the battery is connected to the BMS via one of the balance connector leads (the black one). That allows current to flow from the load’s negative through the B- of the BMS and then through the balance connector to the battery. I was dealing with a similar issue a few days ago, and I think the only feasible way to solve this is to rewire the loop key so that it disconnects the positive side, i.e. disconnects the load’s positive from the battery’s positive. Hope that helps!

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Damn really? I was looking into that and thought (a) there cant be too much amperage running through that tiny 18gauge balance wire so I thought that wasnt feasible and (b) it didnt amtter which side the loop key was on. Thanks for the insight though.

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no prob. Yea I’m surprised that you didn’t burn the balance lead when you spun up the motor after the key was unplugged, but I guess a short burst current doesn’t do much harm.

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I mean, I rode it around the block at an average speed, lol. Oh well. I’ll try flipping the loop around

Haha even more impressive – guess you got some good wires then. Hope the fix goes well!