Originally Posted by
Shadowrider
Joe, no short protection on the positive lead from the battery to VPX. Personally I don't think its needed. I think it would be more likely that the fault protection breaker fail versus chafe through the grommet and insulation on the wire. My alternators tie into the vertical power/battery that run through a switch/breaker so they protect the electrical from the charging system. The fault protection on the earthx battery is to protect the lithium battery and to keep a thermal runway from happening which typical happens when overcharging occurs. The fault protection also protects the battery to try and save the cells if the volts get to low. Basically if the volts drop to low it shuts off the battery to save the cells until hopefully soon a charge gets put on it.
I am not running a backup battery system. The electrical system I would run would be completely different if this where an IFR plane. VFR Day aircraft I am not too concerned if I lose avionics. I will just look out the window which hopefully I already am. The one concern I do have is there is a lot riding on the VPX. If the VPX dies, suddenly I will find myself on short final, with both fuel pumps running through it. I may take a closer look at the VPX pro that has a dual bus system so you can run one fuel pump on each bus or possibly run one fuel pump outside the VPX on its own bus. Of course the biggest concern I have with this aircraft is its engine is a piston engine and there is only one.:)