[Huskymaniac]

I got the battery tested at Sears last night and it tested out OK there too. The thing is, they only test the cranking ability and not the reserve capacity so I don't know if the battery is good in that respect. The reserve capacity is supposed to be 110 minutes at 25A of draw. I bought a multimeter with a current clamp (always wanted one) and tested the car under the same exact conditions as the other day. I discovered one thing I didn't think of...the radiator fans. Even though the A/C wasn't on, the car had warmed up enough to kick on the fans. I have no idea how long those fans were running the other day out of the 30 minutes total time I was sitting there. But when they are on, the draw is 35A. I would think the battery should still be OK with a 35A draw for 30 minutes but I don't know how much faster the reserve capacity draws down at 35A versus 25A. I do know it is not proportional. So it looks like I probably did draw down most of the reserve capacity. After the car sat there for another hour or so, it was able to start. So what probably happened is that the reserve was heavily depleted AND the battery got pretty warm. Once the battery cooled down, there was enough reserve left and sufficient voltage to start the car. Ironically, this probably wouldn't have happened in the winter time as those radiator fans would not have been on or been on for very long. Those suckers draw a HUGE amount of current!

Thanks again for the info on the deep cycle batteries. I will definitely change them out before the spring thaw and maybe even before the November rains.