BMS sense wire fusing? What's the ADC input impedance?

RobertGreen

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Mar 15, 2021
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I hardly ever see anyone fusing the BMS cell voltage sense wires, and I was curious if anyone knows what kind of currents are passing through these leads on a typical BMS? I know it must be pretty small, but I have found some tiny fuses with a very high DC AIC rating for cheap and I'm considering putting them in play on my next pack. The sense leads are at elevated voltage relative to ground and each other of course.
Obviously if the current being drawn by the ADC or whatever the BMS uses to sense the cell voltage is too high, then the resistance of the fuses will introduce inaccuracy in the BMS's readings.

I guess my real question is: what order of magnitude would a typical input impedance be for an ADC used on one of these cheap chinese BMS units?
I tried searching, but didn't come up with much handy info. Basically, with the fuses I am looking at, if the impedance is on the order of 10 MΩ or more then the inaccuracy introduced would only be a tiny fraction of a millivolt.

I'm really enjoying reading and learning, and thank you all for the knowledge!
 
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