be80be:
I think the op problem is the led doesn't light with the power backward. But from your link steve it looked like most problems there was in over rating, etc trying to use a 12 amp at 25 or a 20 at 40 as long as the op is using less amps then half the rating he should be good there.
Very true, there probably won't be a problem at that current, but I had to mention it.
Also handy for others that read this thread in the future, that plan to use one for currents closer to the rating. 
From reply #2:-
.... and others are suitable for random fire.
He wasn't kidding. 