I know that charging a battery still installed in the Comanche (Single Engine) is not safe due to hydrogen gas build up. But it is it safe to use a Batery Tender PLus with battery installed since its a much slower charge. Besides the hydrogen gas hazard, will it harm the battery?

I have been doing mine while installed for several years with no problem. The battery minder charges then goes into float mode to keep it charged. I don't remember the specs, but the amperage rate is very low during charge and extremely low during full charge float mode.
My battery minder has a plug receptical in the line and I wired the negative to the ground on the exterior of the battery box and the positive to the battery switch solinoid. I put an in line fuse in the positive side of the line and then ran one end of the plug through the bag bin wall for easy plug in after flight.

Thanks! Thats what I wanted to know

I've been doing it for several years too... last battery was still good after 6 years... I only changed it because I was taking a long trip over several weeks and didn't want the risk of it failing while "on the road". I use the inexpensive one that I bought at Walmart... <$30. Battery is a Concord sealed battery.

Jim

Duane,

I have "hard-wired" my charger exactly as you have described. How did you route your wire into the baggage compartment? I have been removing the empennage access panel to plug the charger into the leads as I can't bring myself to drill a hole in the panel or floor.

Chris

I have wired in the same setup as those above. Since the lead in wire is so thin I just brought it around the edge of the back panel and fastened the panel back in place. It's worked fine for three years so far and my AI has no problem with it. Ray B

I ended up buying a battery minder rather than using my battery tender after reading several warnings from a few articles. Battery Minder has a different model specificialy for the Gil or Concord battery. Currently Battery Minder is running a special if you have a non approved battery tender or other incorrect charger. Just fill out the onlne certificate and fax it in and they will discount the price by about 60 dollars.

I bought mine from Spruce and Specialty. It's a desulfator type and approved for aircraft. It came with leads to hook up to the battery which included an inline fuse. It also came with a set of standard type clip on leads and I occasionally use it on other batteries. $49. Ray B

I also use the Battery Minder for our aircraft. It was highly recommended by Aviation Consumer and does internal checks to make sure of the correct voltage and polarity before it does its thing. The 12 Volt recharger is used on our TwinCo and the 24V version on our helicopter. So far they have worked like a charm keeping the batteries in good shape.