backup battery

[rwarre]

I have a small back up battery wired to my IEFIS explorer. Maybe I missed something in the wiring setup, but it doesn't charge. Do I need to charge it manually?

[hpmicrowave]

I charge my backup battery through its own charging circuit, either from the main system during flight (with reverse current diode protection) or a separate trickle charger on the ground if needed. I do think the manual hints that a backup battery will get a charge from the EFIS during flight but I didn't really trust this as a good way to ensure the backup is always fully charged if it's ever really needed. If interested I can send you my electrical system diagram (RV8).

Cecil

[Live2Fly]

I'd be interested in the backup battery schematics
Please share

[hpmicrowave]

OK, the schematic below includes my Alternator and main battery, i also have a Backup Alternator,, the Backup battery has a 10Amp CB-Switch which turns it on, and a 5Amp CB from the Avionics Bus that will charge it in flight (with reverse current Diode), and is connected to the iEFIS through Backup power connection into the iBox. I normally leave the iEFIS BU power switch on all the time, this way it gets power from Backup Battery, and AVionics Bus when Avionics Bus is on, but I start engine with Avionics Bus Off, and iEFIS just using Backup Power. Hope this schematic makes sense, so far it is working fine in my RV8 with O-360. I bought a bunch of High Power Diodes used in Solar Power systems pretty cheap off of E-Bay and they all work fine (I do check them first).

Cecil

[gd5362]

Very impressive Cecil,
Is there a schematic program for dummies you could recommend and can you explain the purpose of the green colored diode between the 12v+ side of the backup battery and the 12v-. With my limited understanding that would cause a short.

Thanks

Glenn Davis

[hpmicrowave]

I really do use a schematic program for dummies, it's called Microsoft paint!! I can copy and paste from any other drawing to mine really quick, and the learning curve was quick...

Green Diode is a Green LED backup power on light.

[Live2Fly]

@hpmicrowave - great drawing, many thanks.

A couple of questions:
1. Do you have iEFIS or iEFIS lite (I do not see iBox and engine monitor on the drawing)
2. Do you have keep-alive connection from main battery directly to iEFIS keep-alive?
3. Do you keep backup switch On when Master and Avionics master is on?

[hpmicrowave]

Good questions

1. I have a iEFIS Challenger (RV8 front seat) and Explorer in the backseat. I have a separate power switch for iEFIS and iBox but they are powered through same respective CB's for primary and backup power inputs Backseat powered through Aux circuit). With a separate switch I can power cycle iEFIS or iBox separately if needed ( but haven't had to do that so far). IBox regulated power output circuit powers the Radac, SP9 & SP10, and trim and Flap sensor circuits. Separate schematic for those systems. So far no issues there either.
2. I have a keep alive circuit from iBox to the main battery but at this moment it's disconnected as early on I saw some weirde electrical issues I thought was happening through the keep alive circuit (power LED light was on for iBox and Radac when all power was turned off), but I think now that was caused by another issue that has been fixed, so next chance I get to dig back Into the plane where the battery is located (behind back seat and rear baggage compartment) I'm going to hook keep alive back up and recheck it.
3. For engine start I turn on master and backup power, so iEFIS, iBox, G5, Com 1 and Radac are on for engine start, but don't have their power sucked away by the starter, after engine and alternators are on line I then turn on avionics switch and rest of avionics come on line. I leave the backup power switch on. Backup CB remains in so iEFIS and iBox are powered by both the main power and backup power, iEFIS shows volt input from both sources. Backup battery is charged by primary electrical system. I have backup or primary battery switches for my Comm 1 and Garmin G5 backup attitude systems. But usually leave those systems switches in the backup power position.

Cecil

[rwarre]

Having issues getting my back up battery to charge. I am taking the voltage supply from the same connection point as my main buss with a diode for current regulation. I get an error message when I switch on the bu battery power and there is no indication I am getting a charge.