Battery Reserve Capacity Test
 

Good afternoon - the battery in my 07 is leaving me stranded a few times now....only after listening to the radio with the engine off. The first time it was maybe 45 minutes....now...I can get about 20 minutes of radio time before it wont start.

The car can sit for days normally, and start right up no problem.

I wanted to make sure it was indeed the battery - so I swapped in the battery from my truck...the radio runs for a couple hours no problem.

I took the battery to the parts store since it is under warranty - they run their little test and says it good.

So my question....am I jerk if I throw a fit and demand they run some type of reserve capacity test on it or replace it? I asked if the quick test they did was the only one that had - yes they said.

So I feel that if they can't test for reserve capacity, then I should not be the one who has to buy a new battery. But maybe I am looking at it wrong - just wanted someone else's opinion.

I have checked the alternator....charges great. I have also put my charger on it - full charge - doesn't last long. An clamp style amp reader is showing well below the 25amps the reserve capacity is rated at.

How old is the battery? Is it the correct battery (with vent hose). Reserve capacity is not the real test. Maybe the 9-10 year old starter motor is drawing more amps than it used to.