I have a question that may seem odd, but I am really searching for an answer. I have several 37 volt lithium ion bicycle batteries that hold a lot of charge after being recharged through grid outlets. I also have an old RV that uses 12 volt appliances run from 12 volt lead acid batteries, and solar panels on the RV roof, feeding the 12 volt batteries. Now I wonder whether the following idea makes sense: to connect two empty 12 volt batteries in series so they be a 24 volt bank, and then connect one 37 volt lithium battery in parallel. The idea would be to drain the charge of the 37 volt lithium battery "downhill" causing the empty 24 volt system to become charged, hopefully without much wasting of energy.