My MPPT controller has a battery temp sensor, but the wire that it came with was too short to reach from the controller to the battery bank. This left the temp sensor just under the deck, and probably 20-40+ above the temp of the batteries. By extending the temp sensor wire and actually putting it with the batteries, the charge voltage and current went up. As you know "cooler" batteries can accept a higher charge voltage that "hot" batteries. Free power except for the cost of the wire. Thanks for the info re temp at negative post.

Doug
Namaste II Falmouth, ME