Based on info from another site, I just ordered a new rechargeable lithium-ion battery pack for my Pimaster (PM) Auto Temp Controller (ATC) from ebay for $23. It is 12v 6800mAh. The PM runs at 500mAh max - so I anticipate ~300mAh avg (kicking on and off/speeding up and slowing down). This should get me somewehere between 13 and 22 hours of ATC without having to run a drop cord from the RV when we go to the lake or to the races. Can't wait to use it.