When I first bought this, I was at work a few years back and I hooked it up to a car battery tester to read its voltage and cca. IT registered 13.99 volts, 4000 CCA (WOW!). One time the battery in the car died, and the cap managed to start the motor for me (I verified this when the battery registered 4 volts and bad cells). Its been stored in a cool room for about a year or two when I came across it and thought I'd check it out and put it back to work. I plan on putting it under the seat by the battery if this is still good.
Here's what happened when I tested it. Hooked it up to a multi-meter on d/c and it registered only 0.99 volts. Figured I'd give it a try on the battery charger on 2amp trickle just to be safe. Now typically these take a lead from the battery on one post, then hook the other post up to the lead going to the amplifier. The post that's supposed to come off the battery is labeled (+) so I figured in a charging and testing situation use that post as + and the other as - even though its intended use is (+ of battery) to (+ cap terminal) to (+ wire to amp). Hooked up the charger, turned it on, and the needle jumped instantly to 100% and showed charged status. "Wow" I thought. Hooked up the multimeter, and sure enough it registers 13.99 volts. If I hook up a test light to it, it'll light up but drain fairly quickly (say 2 minutes or so).
Now if any of you ever hooked up batteries in series before, you'll know that if you take an old battery and a new one, the new one will pretty much get killed off trying to keep the old one up. Is there any way I can test this cap without hooking it up to my battery and amp and potentially wearing down the battery? Unfortunately this one doesn't have the digital read-out the fancy newer ones do, but I figure since its still holding 13.99 volts, it could possibly be useful still.