Hi Rick: When you discharge for storage, how low do you take the batteries? When you put the new battery on with one at 20% (so you have 100% and 20%), what you may see is that the 100% LiPo is cross-charging the 20% one. I didn't know the MP could do that, but what you're seeing suggests it can. I think you may have discovered a new "feechur!" Cheers Andy Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. The Ground Is The Limit™ ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert