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Board won’t power up - help please!

Asking for help diagnosing a problem:
My board won’t power up and I’ve tried two flipsky anti sparks (the 200a 2020 ones) one of which was brand new.

Build spec:
10s3p 30q
Flipsky anti spark
2x flipsky 4.12 vesc
2x 6374

Build thread

Battery is fully charged - checked with multimeter
Occasionally after disconnecting and reconnecting the battery manually the board will power up again.

The anti spark button illuminates when pressed but nothing powers up.

The input terminals of the anti spark only read 3v regardless whether the button is on/off.

Please help!

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can you take a picture of where you are measuring the voltage from?

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Make yourself a loopkey and test without the antispark setup. See if that’s the faulty variable in the board

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Have you measured the voltage coming out of the switch?

Sounds like a BMS issue to me, do you have discharge BMS ?

Seems like it could also be the Y cable making the connection between the vesc : for instance it happens to me once one of the solder between the XT did brake under vibration causing the same issue maybe check that connection and change it to try.

If you only getting 3v at the anti spark input you battry is the issue/joints plugs up to it. Id expect as soon as you apply a load the v drop. Why you think you’r getting full voltage at the battry.

@RhinoTH Pleas can you confirm your measuring Voltage at the anti spark INPUT/SUPPLY to make sure we don’t going down a rabbit hole

I’m thinking Broken joint/super high resistance between p groups or BMS I don’t see any details on how the battry was built in you build thread only

So it is a charge/discharge

I tried to bypass the switch and plug the battery direct to the splitter And it also didn’t power up, so I’m guessing battery/BMS is correct

What’s my best options next, strip the pack down and measure every group? Just swap out the BMS? Bypass the BMS on discharge?

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Next I would get to the balance leads and confirm eatch p group voltage with your multimeter. Your BMS is separate so shouldn’t be to destructive to do so.

Then I would checks solder joints

The edge of your pack looks prity squar. Are your p group connections done with nickel if so did thay get beefed up like this

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So the P groups are joined by folded nickel in the middle and copper braid on the edges.

I’ll check the voltages tonight

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I would try to bypass the BMS to me it looks like the voltage is there but something shut down when you try to get more than some mA out of it

To expand on this. Overcurrent on the BMS might be tripping as the fat caps on the esc try to charge instantly.

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Good point.

If you disconnect the ESCs, does the antispark input still read 3V?

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So I’ve messed all the P groups and they range between 4.17 and 4.19.

Based on this I’m guessing all the connections are in good condition? So probably best just to bypass the bms discharge?

I don’t think it’s recommended to have the anti spark plugged into the battery and not to the esc.

Thanks for you’re continued help everyone!

Dose not rule out high resistance joints that will only show under load

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