system 3 prong

I was hoping to find a charging unit for ground power when i am in my hanger. I typically use my battery, but I am afraid i will drain my battery over time. any thoughts?

I use an accessory plug

I have an accessory plug (Cig Lighter style) in the baggage compartment that runs through an independent fuse directly to the battery. I can use it inflight for 12v, but I have a small charger I take on crosscountry trips that has the clamps cut off and an accessory plug on the end.
When I am performing tests or running electrical equipment, I plug in the charger to keep my battery topped off. If I run the battery down, I can connect and charge overnight - all without removing panels on my aft mounted battery.
Cheap and lightweight - my favorite option

Bruce "FM" Edwards
RV-8, N391FM, 469 hours - flying