Bestech BMS, Switch not working

That makes sense. But I measure -2,45 Mega ohm. Isn’t it weird that I measure a negative resistance?

Try reversing the test leads.

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If I reverse them it won’t show the resistance, which makes it even weirder

I must have done that 20 times now and repeatedly gives me the same result. I get a measurement of -2.45 Mohm with the test lead the one way constantly and I get no measurement when I switch the test leads

The negative resistance is measured between the 2 white leads of the BMS. The switch is working fine regarding that I get 0 ohm when the button is pressed in and no measurement (probably too high to measure) when it is in it’s off position.

OK, what I’m trying to figure out is if you have removed the switch and isolated the leads. If so is the BMS off? when you touch the leads together is it on? All the switch leads do is complete the circuit, they are not positive and negative.

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The board turns on when I plug in the battery, no matter if the leads are touching or not. Then touching the leads or not doesn’t have any effect

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then the BMS is bad. You easiest solution is to contact BesTech and get a replacement.

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I think so too, thanks. The problem is that I didn’t buy from Bestech directly but from a seller. I will contact him now

He will send me a knew one, but I want to try to fix this one first

Can anyone tell me if these pins are supposed to be shorted?

Respectively, what this part is used for?

thats the temp sensor

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Thanks! Do you know how it works?

Is it supposed to create a short when the temperature-cutoff of the BMS is NOT reached? (and open when it is reached?)

I honestly have no idea how it operates. I would ask [email protected].

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Ok thanks!

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It’s probably just a thermistor, always a closed circuit that varies resistance depending on temperature.

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Somehow my problems solved themselves… What happened: Since the button was not changing anything and the BMS and VESC where powered on anyway as soon as I plugged in my battery I didn’t have my switch soldered to my setup anymore when I started testing my board for the first time after having loctited and secured everything properly. The board itself performed great for about 1km and then suddenly powered off. I already thought I smoked something because there was no more spark after unplugging and plugging back in my battery connection. Then I shorted the 2 white wires of the BMS manually again (had tried it before that test already) and the VESC turned on. So I soldered back on my switch and ever since everything is working just fine.

Thanks a lot for your help guys!

Edit: VESC issue solution: Fully charging my battery solved my issue that the power delivery was poor. Disconnected my battery had a Voltage of 37,5V and as soon as I powered my motor with it it probably dropped below 3,6V or 3,5V which triggered the cutoff start/end

I’m having his exact same problem. I tried what you said I and it didn’t fix anything

I edited my solution reply.

I guess you are talking about my BMS related problem that the switch is not working? Do you also have the Bestech HCX-D223V1 10s BMS and this problem:

Maybe some pictures of your BMS could help :slight_smile: