How do you wire all these balance wires?

All of the voltages on the cells are correct, but the voltage drops about 3 volts from the total voltage when it goes through the bms. Primary positive and b- is 45.2 and primary positive and p- is 42.1… how does the bms draw that much?? Also, when I plug it in to the vesc nothing happens and the vesc voltage is 2.7-3 volts… I have no clue what’s wrong. I’ve read that my vesc might not be capable of using a bms.

Your vesc can definitely use a bms what you’ve heard is nonsense. I would check the main connections, I had something like this the other day and it ended up being a cold solder joint in my b-

1 Like

Alright I will try re soldering the negative battery connections (b- and p-)

How close we’re all the cells voltages before you connected them to the BMS? What was the difference between the highest cell voltage and the lowest in your 12 cells?

Were not we’re. Fing auto correct! L

They were balance charged by my other lipo charger individually. They should all be about 3.85 volts.

Good. It’s weird that the P minus output is reading 42.1. It almost seems like a 10s BMS has gone into over-voltage protection and is bleeding off 3 volts.

IDK. Even at 42v it should turn on your ESC. You do have an anti spark switch right?

The bms has an e-switch but it has no effect on whether the esc works or not. I have no clue what’s wrong.

Have you tried charging, you need the eswitch on to charge

1 Like

Ok so I plugged in the charger and the vesc turns on and flipping the switch has no effect. The vesc stays on at all times and I’m pretty sure the vesc is being powered by the charger because when I unplug the charger it turns off. 15418904015001858382445

So you have the vesc connected to P- and batt +. The charger connected to C- and batt +. And the battery connected to B-.

If all that’s right well then I’m assuming that the bms might not be registering that the battery is connected. The reason the vesc gets powered by the charger is because the p- and c- are usually connected together. I would check the switch and make sure it is turning on the bms when charging/ discharging

Also if you have a multimeter check the continuity of the wires, they should read very low. That will let you know if there’s a bad connection

So you’re saying my wiring is wrong? If my vesc Powers up when the charger is plugged in, the way it is now, can I just switch the p- and the c-? Because right now that seems like it would make it work. The batteries are charging the way it is right now, but when you unplug the charger nothing can discharge the batteries

The charger will turn the Vesc on even if the bms is turned off. (that is normal) If everything is wired correctly and there are no low cell voltages but bms is not outputting full voltage to the P-, then the most likely problem is that the e-switch wires are either broken somewhere between the toggle switch and the circuit board or the solder connection of the e-switch wires to the circuit board is faulty so that the bms is not turning on when you flip the switch.

I have seen this problem with the e-switch wires before. I believe it is because of the stiff wire they use. Also try connecting the e-switch wires together without the toggle switch to rule out the possibility of a faulty toggle switch.

1 Like

I understand what you’re saying, but by the looks of the bottom of the switch wires on the circuit board there is nothing disrupting the connection to the switch. 1541893044781104415844 Uploading… The wires are covered in sugru type stuff so I can’t really tell. I think after the batteries fully charge I’ll check the connection by putting a wire between them. I checked the continuitity of the toggle switch and it isn’t faulty.

There can be a break somewhere in one of the wires. This has happened before. try disconnecting the wires from the toggle switch and check them with your continuity meter between the solder joint and the end of the wire and check each wire separately.


The e-switch isn’t messed up and my vesc seems to work now without the charger plugged in. I don’t know what changed other than the charger changing the voltage of the batteries. Also, is the e-switch supposed to completely cut off power to the vesc or what Because for me it just lowers the voltage 6 volts. I think I’ll just use a loop key in the battery wire to turn the board on and off completely Because from what I see the switch just lowers the voltage.

yeah looks like your switch is a bit messed up

if you plan on doing the loop key yourself, do alot of research because ive seen some gems scattered about materials that you can use to strengthen the key, and other improvements to enable the switch to last longer and more predictably :slight_smile:

1 Like

So I unplugged the 4 batteries from the bms to measure their cell voltages and the 1st battery (the primary positive battery) had 12.7 volts and the other three had 12.1/.3 volts. It might be unbalanced because I was charging it and i didn’t give it time to balance them but I’m not sure. Is it because the first battery is getting the charge first?