Bestech BMS, Switch not working

Hey guys,

I finally found the time to put together my first esk8 and I currently have a few issues I could not find an answer to on this forum.

BMS: I’m using @Namasaki’s 10s Lipo battery setup with the exact same Turnigy 5000mah batteries and the Bestech HCX-D223V1 10s BMS. The issue is: for some reason my switch function doesn’t work. It is always on, so the only way to turn on and off my board is to plug in and out one battery connection. I checked the resistance of the switch and of the solder points of the white wire and there are no shorts and the switch is working as it’s supposed to be. Has anyone had a similar problem?

Vesc: I’m using the hobbyking vesc and with the settings from this thread because I have the same 6374 sk3 as well. The issue now is that if I use 36 as the cutoff start voltage and 35 as the cutoff end voltage I can’t do a motor-detection. I measured the voltage of my battery pack and it is a bit over 37V. So I lowered the cutoff start and end to 33 and both the motor detection and the power delivery worked fine. Then I put the cutoff start and end back to the previous settings (36 and 35) and the power delivery got really poor and the motor only pulled 4A. So I think my Vesc is somehow getting a wrong voltage measurement. I found a thread witch a similar problem on the forum and charging could help here so I will test that out tomorrow. But maybe someone has an other solution to this problem too?

Same for me, my voltage when on is about 3-4v lower

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If you test the bms without the vesc connected, it will seem to stay on after your turn it off because there is no load to drain the voltage down. Even with the Vesc connected, it takes a few seconds for the voltage to drain down.

I actually never measured the voltage when my battery is connected. Thanks, I will check that tomorrow too

Thank you for answering so quickly! Unfortunately I don’t really understand how this could affect the switch not being able to turn on and off the vesc when it is connected or affecting the voltage measured by the Vesc.

Ok, I wasn’t sure if you had the Vesc connected or not. Some people in the past had thought something was wrong with the e-switch when they tested it without the Vesc connected.

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I will elaborate my problem further: When I close whole the circuit of my battery, Vesc and BMS the Vesc turns on, no matter if my switch was in the on or off position. Then I test the switch and again: no matter the position of the switch the vesc stays turned on until I open the whole circuit manually (unplugging a battery wire) again.

Are you using a simple button switch with 2 solder posts or the one with led and 4 solder posts?

One with Led and 5 solder points, 2 for the LED and the other 3 pins are for NO (normally open), NC (normally closed) and ground where I soldered to the NO and ground pin. I’m not powering the LED though, but that’s the way I measured it too and the resitance was really big when open and really small when closed

Did you wire it like this:


Exactly, only the green wires are connected at this stage

It is very uncommon for the e-switch to fail on that bms but it is possible. I would double check the e-switch wires where they connect to the bms and make sure there isn’t any solder bridge. also double check the wires that they aren’t touching where they solder to the bms.

Then email bestech about it.

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I will link my post here because I have similar issue

I rechecked the resistances and the Led switch is working but there seems to be a short between the upper right and the 2 bottom pins on the BMS.

I guess that’s not how it is supposed to be?

Maybe the wires are touching together under the white goop they put on it.

Somehow I measure a negative resistance when the switch is on the off-position. Any idea what this could mean?

I assume you have tried removing the switch and isolating the leads to see if it switches off?

Yes, but I will remove the switch again now to check if the negative resistance is also measured only between the 2 white cables

I’m not an electronics engineer but I think that the 2 white wires when connected, close a circuit. And when you test them with an ohm meter you are closing the circuit. Therefore you are reading the resistance of the circuit.