Ground Power Capability?

[MichaelFarley56]

Hello All,

There's been some chatter among other homebuilt aircraft forum boards about what builders have installed in their aircraft to serve as a ground power option. In general, there seems to be two options; first is to install some sort of power plug that has the amperage to actually crank an engine, while the other option is to install a battery tender/charger in order to power up avionics, test wiring, and trickle charge the battery.

When I built my Waiex I didn't include any sort of capability for this, but I'm slowly starting to reconsider with the thought of adding something very small and lightweight to act as a battery trickle charger in addition to the ground power capability. I can see the benefits to this as I've had to pull my cowling two or three times in order to charge the battery during cold months after a lot of ground runs. Personally, given the electronic ignition design of the engine, I'd rather always make sure I takeoff with a fully charged battery!

In theory, this seems like it could be a pretty simple affair. Run some sort of medium gauge wire from the positive terminal of the battery down to the bottom of the engine mount, putting it in an accessible location through the cooling exit area so I can clip it to the positive clamp of a battery charger. The negative side could be done in the same fashion, or simply by clamping that lead to the exhaust pipe or similar grounding point.

Before I do anything though, I wanted to get your thoughts. Has anyone done something similar? Any recommendations? Has anyone done something similar?

Thanks everyone!

[sonex892]

Sorry I don't have a better picture Mike, but here's what I did. Its fitted it to the box section on the right lower engine mount. The fixed plug or socket is mounted perpendicular to the cowling. The cowling has a small square hole just large enough for the plug to pass through. The plug is the same type I've seen used for charging fork lifts. They come in many sizes

It can be used to charge or jump start with the cowling on. Wire is 8 AWG direct to battery terminals. If you only wish to charge a much smaller wire gauge could be used and it could also be fused

Steve
Sonex 892 3300 TD

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[radfordc]

I ran a wire from the battery + terminal to a 1/4x20 threaded fitting that fits just flush with the inside of the cowl. There is a 1/4" hole in the cowl. I screw a brass bolt into the fitting and clip the battery charger to it. Other charge lead clips to the exhaust pipe. Also works for jump starting if the battery is flat.

[vigilant104]

Jay Gibbs made a small hole in the cowling cheek so that an aluminum tube could be pushed through the cheek and threaded on to the positive terminal of the battery relay. I can clamp the the positive lead from the battery charger to that tube and the negative lead to the tiedown point and I'm good to go. The threaded aluminum tube stays with the plane. This weighs almost nothing and the price is right. I'm thankful he installed it every time I avoid opening the cowl just to apply a charger to the battery.

P.S.--oops, it looks like I cross-posted with Charlie. His approach is much the same as described above, and would work if the "+" terminal of the battery relay isn't easily accessible.
Mark

[tonyr]

Hi

I fitted a 165A Anderson plug to the underside of the battery box, allows the engine to be jump started easily. If you were only going to provide charging current you could go with one of the smaller versions i.e. 50A. You need two plugs, one for the fixed and one for the jumper/charge leads. The fixed connector is wired direct to BATT+ and main earth. I agonised over fitting a ground power relay but decided it was extra complication not required as the run is very short.

A small door in the RH cowl provides access and makes recharging the battery a breeze.

This image has the mating connector plugged into the fixed connector under the battery box.

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