E-switch problem

Even with the Vesc connected it takes several seconds for the voltage to drain down

@ekitesurfer was having the same issue with his until he connected the Vesc after which it works fine.

Youre right, I have connected the vesc and the voltage drain down, but not to 0volt but to 3volt… Is 3volt normal?_

Yes. 2-3v is normal

Yes is normal. I will check mine too when i get back. But when i switch it off my vesc is off so is all i need :smiley:

Glad you solved your problem pjotr

Hey i bring back this post with some new questions. I read that the bms e-switch should be on during the charging … but my board is charging with the e-switch on and off…

Is this normal ??

Also it happened that if i leave the board with the e-switch off and the loop key connected, when i turn the switch on the board wont turn on… i.ll have to disconnect the loop key and reconnect it.

Any idea with this??? Thank you

The instructions for the bms say that the E-switch should be on while charging. That means that it should be on. If you don’t turn it on, them maybe the bms won’t balance your pack properly or protect it from shorts or overcharging.

So if you ignore the instructions and something gets damaged, it’s on you.

Oh i see… it was strange for me because a few days ago i forgot to turn it on and thought it will not charge unless it is On. but i guess it make sense what you saying here.

And yeah i dont want to ruin it but was something unexpected for me hehe.


I measured about 9V across the switch and fuse. Is that right? I was expecting to get 36V since it’s connected to 10s4P battery. I have a 12V switch that would not work when wired to the bms e-switch. Where did I go wrong? Thanks for the input.


You wont get battery voltage on switch tho. Through switch will go less curren than the main battery cables.

Something strange that i saw tho is that when i have the vesc connected the switch is working just fine. On-37V off 0V

But if i remove the vesc and only connect my multimeter the eswitch is not working and is always on On 37V off 37V

…so it would not be able to power a 12V switch that I have? What kind of switch do you have?

12v switch you mean the one you connected to the bms wite wires ? That is the maximum voltage that the switch can handle more then that and it will short. So the 12V one should be just good

What is the rest of your setup ?? how did you connect everything else . and what is not working for you?

The switch works wether your vesc is connected or not. The reason it appears to not work is that when the vesc is disconnected, there is nothing to drain the residual voltage down. When the Vesc is connected, it’s Caps drain the residual voltage down

Did you mean the 12v switch is not turning the bms on?

My set up is similar to diagram #2 as Bloop with XT90s. Currently I have everything connected between the battery and the BMS except VESCs. I connected my 12V switch (Ulincos Latching Pushbutton Switch ON/OFF with Blue LED) to the BMS 2-white e-switch wires…push to turn on but blue LED did not lit up. How can you check whether the bms is on? Thanks.

The 2 white wires are not meant to supply voltage for a switch light

As @Namasaki said… the eswitch will only turn on and off the bms…

the button led will need the 3th pin connected too -> something like this

But id suggest you dont worry about the led… just on/off and see if the vesc is working.

when the switch is connected to the bms e switch, How do I check whether the switch is turning the bms on?

No way to check bms on or off unless VESC is connected?

What @Bloop said, Connect the vesc and turn the bms on. The vesc should turn on. You must have the balance wires connected though, or the bms will not turn on.