From Light Speed
Stormy said:
Have a dual lightspeed system ordered for my extreme 360 coming. Looking for different ideas of backup electrical systems. Dual Bat. or backup alt..
any ideas?
Stormy, This is the last thing I have to buy for my plane. My plan is for a dual LSII+ ignition system. I like the idea of the P-mag, I have discovered or come to personal conclusion however mixing and matching different EI systems is not an efficient thing to do. Since the LightSpeed systems are meant to work together. Since I am not using one magneto or P-mag, I also have a desire for some back up electrical power.
One thought is the main battery should provide enough power with out back up. Battery failures are rare and catastrophic alternator failures vs. just dyeing quietly are also rare. I am not comfortable with that so I am using the suggest wiring that LS recommends:
http://www.lightspeedengineering.com/Manuals/PS_Diagram.htm
I have talked to Klaus and he runs no second battery on his Vari-EZ. The aux battery is isolated and runs one ignition module only. Also VERY important is DIRECT WIRES from the battery to the module. In other words DO NOT route through the mater relay or busses. The only thing between the battery and the module is a single switch and circuit breaker. In other words you will have two HOT BATTERY BUSSES, One off the main battery and one off the aux battery. Each battery will have a hot wire running right to the respective module switch. (A fusible link may be a good idea). A few "ON" lights or power lights may be good on the ignition switches if for no other reason than a reminder to turn them off. Also some switch guards might be good, not the red cover type, but the metal side guards that reduce accidental activation. The red flip over guards are cool, especially for things you will infrequently switch, but for every day use they are a pain in my opinion.
The down side is you MUST turn both ignitions off after shut down or you will drain the batteries, so you have the master, ign L, ign R and may be a avionics master off to shut down and power up.
Going to dual alternator I feel is overkill and the KISS method - Keep it Simple Stupid, is most reliable. You can't get much simpler than a simple circuit, battery, wire, switch, device and wire protection (CB). Also some attention to a good ground should be of prime concern. Suggest a central ground off the battery. Also running two wires side-by-side, with separate connectors is not a bad idea.
George