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2002 BMW 325i Electric
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Discussion Starter · #1 ·
Hey all,
I recently have been trying to add sensors and stats to log information about my car as I am driving it, and once necessity is the amperage. I have a 1000 amp/75mv shunt hooked up at the output of the negative battery pack terminal. But when I connect the shunt to any measuring device, I tried my Arduino with a shunt connector and an out-of-the-box battery SOC gauge, they freeze up and flicker.

I have tried using isolated power supplies to these devices (9v battery, 12v car accessory power, full 72v from battery pack) but that didn't fix the issue. I was also aware of EMF, so I added some ferrite collars around every cable going to my measuring devices. No change.

The only luck I have had is if I am give it extremely low throttle in neutral (maybe 1 amp drawn), the display seems to work as intended. The moment as the draw increases any amount, it freezes up again and goes back to flickering.

Here's a clip from one of the first times I tried and noticed this issue:

Any help or advice is greatly appreciated!
 
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