My Stampede 4x4, with datalog of the Castle 3800

[BrianG]

For some reason, I just now saw this thread.

It's hard to see from the graphs posted, but it sounds to me like your 100A logger is not reading high enough to see the real story. If you look at the datasheets for the actual hall-effect devices these loggers use, you'll see they lose accuracy almost exponentially above their rating - there's just not much more headroom in those things.

I've 147A on a CRT.5 on 3s geared for ~35-40mph, so it's very possible your 4x4 is pulling more than 117A.

To see if your logger isn't enough, you can study the graph a bit more. Look at all the peak currents. First of all, the current waveforms should look almost exactly like the voltage waveforms at that point in time, just reversed (voltage dips while current peaks). If the voltage has a negative peak, but the current peak looks flat, then the logger is chopping the rest of the peak off. Also, take a look at all the places where the voltage is the lowest - the currents at those times should be higher in proportion. If not, the logger is limiting the reading. You could also take readings of the battery voltage dips at various points in the graph at (10A, 20A, and so on), calculate the battery internal resistance at those points , get a graph of battery resistance over load, and then see if the current draw matches voltage dips at suspect points.

BTW: If you want, zip up and attach the raw logger file. I can load it in the ET software and see the details and let you know what I find...

Thanks for the reply, Brian. Any input would greatly be appreciated.
Let's see if I get this right with the files.

I also included a little E-revo run that I did. It shows 120 amps, but it was only geared 24/68, 42mph, pretty conservative by my standards, yet I was shocked to see the amps of the 2 vehicles so close. The Stampede is half the weight, on half the voltage, same speed, within 3 amps of each other, I have been checking the graphs, in small increments at my highest amp points, and have always seen the max amps, and the lowest voltages at the same points. But I'm very new with this, so maybe your eye will see something my doesn't.