FOCBOX UNITY $299 | R-SPEC DRIVE KIT $588

Bms question: what does this mean?


#1

My battery pack is 10s5p. When i connected a bat indicator direct to the bat(before bms) it showed 64% like this

But when the indicator connected after bms it showed 0% and no light

I used multimeter after the bms, it showed 36v
I think the bms is cuuting off, its only 36v. Doesnt make sense.

One more weird thing, that i connect bat ( after bms) to vesc, the led on vesc flashing blue repeatedly. It is like there is no amp is coming out, and the computer could not detect a usb device when i i pluged it in.

Then i switched to laptoplike charger, the veac connected to computer with no issue.

@longhairedboy @lowGuido @MasterCho @Jinra @Michaelinvegas


#2

Is the meter negative going to P- or B- on the bms? You should be going to B-, assuming you have an eswitch on the bms. If you’re running a power switch after the bms, you should have the meter after the switch or it’ll always be on.

How are you wiring the meter?


#3

@Jinra thanks for quick reply. In the case that it showed 64% , yes the meter connected to the b- of the bms. In the case it showed 0% it connected to p-

One more weird thing, that i connect bat ( after bms) to vesc, the led on vesc flashing blue repeatedly. It is like there is no amp is coming out.

This is the bms i am using


#4

Yea sounds like you don’t have enough current going through. Did you wire battery negative to B- and VESC negative to P-? Battery positive doesn’t go to BMS at all right?


#5

Yes, i solder it right, negative bat to B- and negative power out to P-

And the computer could not detect usb device when i i pluged it in.

Then i switched to laptoplike charger, the vesc connected to computer with no issue.


#6

the BMS has probably cut out because of low voltage. charge your batteries and try again.

36/10= 3.6


#7

It is looking like one of your cell pack is not correctly link to the BMS (on the JST connector), causing a shutdown over a Undervoltage error…


#8

Thanks @lowGuido

@JohnnyMeduse thats a possibility. I will check that this weekend. Thanks


#9

just fyi, low voltage cut off is 2.9v per cell, I’m guessing it may be an incorrect balance lead as well.