[sanddrag]

I'm not so confident the controller can count for volatge very accurately. We got some numbers that just seemed amazingly low under load sometimes.

If you have only the Chias driving I wouldn't suspect them shorting at all. However, if by some stroke of bad luck you got a defective one, it could be internally shorting or arcing perhaps. Assuming that you have one motor for each side of your bot, run your robot up on blocks (wheels off ground) and listen for a different tone when running each side separately. Slowly advance the control for one side of the drive system and get a feel for when it begins rotating and the sound it makes at different points along the range. Do the same for the other side and listen if there are any major differences in the sound. Certain sounds can indicate things binding or a lot of drag in the system too which can lead to the battery draining quickly. This was a big problem (now corrected) for us this season.