So how would something like this work if you have an isolated bus with your motors on the battery bus? Do you need this on both the isolated AND non-isolated sides? Seems to me that would cause a problem...

@qrk - GF is for safety. Comms are just fine

@dandavis - I'm working at 25kHz, not 25Hz and I'm moving a lot of power.

Thanks for this, I didn't think to look for the saturation flux density. I appreciate the info!

I'm not looking for anything that complicated or expensive. Those systems cost upward of $40k, I'm looking for something in the $600-$1k. I've seen them before, they look similar to a small rotor brake, but I'm having a hard time finding one.

@JohnD - so there's no need to meet any specific impedance - I could det it to something like... say 50 ohms, it's just the act of routing them as a differential pair that rejects the common mode noise?

I'd like to use my onboard processor to calculate as accurately as possible, how much energy I've used. Some functions use more energy than others, so from the look of that equation, I'd have to fit a curve to the data I read, then integrate it?

so if I sample 1 watt at let's say 10Hz, each sample could be representative of 1/10th watt second, summing all 10 samples gives me 1 watt second, etc etc...? That seems a little too simple. And I'm using a simple constant 1 Watt case...