Larry F. writes: > I also have a very small backup battery and electrical > system to power the pumps if I lose my main electrical system.
I've done the same and recently wiped out (over a 1½ week period) my smaller battery by flipping a switch that links both the main and back-up system. I connect them with the switch and put a float charger on when I leave the hanger. After a few days I'd noticed the smaller battery had lost voltage (separate voltmeter on both systems). When I went back approximately a week later, I found the 7.2 Ah gel cell dead. It may be the secondary system master switch that has failed - I haven't gotten into it yet to see. The primary battery is a 35 Ah AGM battery. Secondary is a 7.2 Ah gel cell. Both batteries were at full charge, or close to it, when I attached the float charger. The main battery is fine. The secondary is dead a doornail. I'll report back on what I find has failed, the battery or the secondary battery master switch. A few days after I leaving the plane with the float charger attached and both batterys in parallel, I noticed voltage had dropped from 12.76 to 12.46 (it should have either gotten higher or stayed the same with the float charger on it). I wondered about that and left things as it they were to see what would develop. What developed was a dead gel cell. So . . . this is a general query about the wisdom of connecting two different types (gel cell and AGM) and capacities (7.2 and 35) in parallel. Opinion around the airport is divided, as it is with the electrical gurus I've checked with on line. >From my current experience, it seems like the wise thing to do would be to put a charger on both batteries individually from now on. Meanwhile, I'll figure out exactly whether the battery is dead or the secondary master switch has failed. How have you got your secondary system configured Larry? With my top mounted Ellison my engine is totally dependent on a fuel pump. I have two, but both (for over 1200 hours now) are dependent on the same electrical system. It was to eliminate this vulnerability that I installed a second battery & bus. Even though it's never happened, a solenoid could fail, a master switch could fail, or something completely unforseen happen to cause loss of the electrical system. That would turn me into a glider quickly, and I would have felt pretty dumb had it happened knowing the possibility existed. ******** Those who respond, please don't quote this whole thing. I cringe every time I post something on KR net because so many refuse to delete the post they are responding to. You really don't need to quote more than the title. If we can't remember what was written the day before we shouldn't be flying airplanes. Thanks, Mike ____________________________________________________________ Do you need to diversify your portfolio? Click here for informaton on trading currency. http://thirdpartyoffers.juno.com/TGL2141/fc/BLSrjpTIyViDNCz3yasIHjcBFQLpOqdOpnGPgJw0SDwR9l7ZmsUvTG8yEuc/
