I've been using dual 5-cell packs and regulators for years...or a least ever since I decided to put a $2000 ++ engine in my planes! So far, it has been working great. Just about every equipment failure crash that I have experienced in the last 36 years or so has been caused by a failure of the electrical power system (not counting engine failures). It was either a battery pack shooting craps or a switch failure or a SINGLE plug/wire to either of them. I decided that two Ni-Cads and switches were CHEAP insurance. I currently use dual Maxx Products Miracle Switches with 5-cell Ni-Cads....Just because Ni-Cads are familiar to me and user friendly. The Maxx Miracle Switch is a regulator configured so that if the switch fails, it fails ON. I've been using the 6 volt version but I'm going to try the 5.4 volt variation next. I check the voltage of each pack prior to every flight. I Keep a logbook for each pack and I record the discharge capacities and charge info every few months.

That's my $.02 worth.

Tailwinds,

John