At 01:48 PM 4/14/2009, you wrote: >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. >Mike ========================================================== Both my batteries are lead / acid type batteries. http://www.krnet.org/mvn2004/040929139.jpg I have no idea how two dissimilar batteries would interact. Both my fuel pumps are connected to the main buss via breakers, switches, etc., in a standard electrical circuit. I have a switch that connects the output of my B&C alternator, through a relay, to the main buss for charging the main battery. The backup battery is connected to a separate buss, then to breakers, and finally to the switches on the red panel (see photo) http://www.krnet.org/mvn2004/040929271.jpg and then to the fuel pumps. I have a separate switch, the white switch on the left edge of the red panel, that connects the output of the alternator, through a relay, to the backup battery. I will on occasion, while flying, tie the alternator output to the backup battery to keep it charged. At that point I am charging both batteries in parallel with no problems. The only other possible connection between the two busses is if I forget to turn off the main pump switches before turning on the backup system. On the upper right side of the panel I have volt / amp meter that allows me to check both batteries for charge before startup. No backup battery, no fly. I have on two occasions "killed" the backup battery. Once by leaving the volt / amp meter switch in the "backup battery" position. In the course of a week or so the meter drained the battery. Another time I managed to leave the switch that operates the relay connecting the alternator to the backup battery in the on position and the relay drained the backup battery. The reason I connected that relay to the backup battery buss is so I could operate the relay and keep the battery charged in flight if I lose the main buss. I suspect you have something draining the small battery, maybe a problem of dissimilar batteries having a different internal resistance or charge rate or something. My KR has set for several months on a couple of occasions and both batteries still read 12+ volts with neither having been charged. I'd suggest you check all the system components and then install two batteries of similar type and then see what happens. Larry Flesner
