Dual Batteries vs different systems
Most of my electrical system failures have been alternator failures but not all of them. Dual battery systems would no doubt help in those cases where I did not notice the annunciator and I had to enable the seconday battery. If it was all switched automatically I would probably just fly farther before elements in my LED displays started flickering, com becomes intermittent... This is just my experience but I have had several electrical failures and several vacuum failures and I would hate to give up the complete independence either one in favor of two of the other and I certainly would avoid trading one for a partially redundant single type system. Last week I was flying the RV-6A down to Ft. Smith, then over to Ozark, and finally up to Walnut Ridge before returning to Fayetteville, Arkansas. The low voltage light came on on the last leg of the trip. It was VFR out over the Ozarks so in my save the battery for com on the last part of the trip decision making, as I had done before in the Archer that we owned for over 20 years, I turned off the master and used pilotage for navigation. Even though I have a vacuum system with a AI and DG and some direct reading gauges I was struck by the great reduction in information available to me as opposed to the Archer with electrical systems powered down. The losses were not critical in that setting but losses of such things as engine RPM knowledge and outside air temperature were discomforting. Then as I got closer in to Fayetteville and powered up the systems and call the tower I had to wait for the SL-60 to initialize, then set it up for nav before I could focus on flying the plane and using it for com. I think when things deteriorate to the survival level (and they will) the old totally independent system concept (steam gauges) has a lot going for it.