I have been running my SLA batteries through John DeRosa's test "rig" found he

http://aviation.derosaweb.net/

This is the second year I've tested them, and the batteries have been in service since March 2011.

I have two 12v/7.5ah batteries I purchased from Academy Sporting Goods (chain store) here in Austin, Texas for ~$20 each. They are primarily sold for deer feeders, electric fences, etc. They are sold under the trade name "Wildgame Innovations" and are listed as Model #12vb.

When I ran Battery #1 through John's testing protocol, I got 5 hours 35 minutes till it dropped from full charge to 11.5v. It lasted another 1:37 till it dropped to 10v, at which time I terminated the test.

Battery #2 is currently on the test rig, and has just hit 11.5v at 5:30 into the test protocol. I expect it will last to 10v the same as the first.

I do have a Werker 12v/2.9ah backup battery...config on my glider is such that it's easier to mount 1 big battery/1 small one vs 2 big ones...so I use the main all day and the 2.9ah to go into a "limp home" status if I ever need it (haven't yet).

The Werker is right at 1 year old...and it appears to be fading fast. One would think it would have ~39% of the bigger battery's life (2.9/7.5) or something near 2 hours 10 minutes, but in my testing, it dropped to 11.5v in only 55 minutes.

Wish the sporting goods guys would stock the smaller batteries in something other than 6v sizes...but they don't.

Hope some of that helped..

Rob S.
ASW-19b
ZAP