I have a 03 Subaru WRX and at a recent oil change at a local chain they tested my battery too(without me asking). Anyway the little slip of test showed full cranking amps but only half charged. They said drive it more and it will charge.

The thing is the car is driven daily between 5-40 miles.

I’m not a battery expert. Perhaps someone who is will explain this.

If the battery has full cranking amps how can it be only half charged?

Proper response: If I had wanted my battery tested, I would have asked for that service…Please do not perform any services unless I ask for them…"

Your battery is FINE. Drive on.

If that battery is the original one, it may actually be time to replace it.
If the battery is beginning to fail, your very expensive alternator will have to “work overtime” in order to keep it charged, and you could wind up killing the alternator over a period of time.

I would suggest that you go to Sears for a load test of the battery and charging system. Supposedly there is a fee for this, but I find that more often than not, the Sears employees just wave you out without charging you for the service.

If the load test indicates that you do need a battery, tell the Sears guy that you will be back later for a battery, and then drive over to Costco. The Kirkland Signature battery at Costco is made by the same company (Johnson Controls) as the Sears Diehard Gold battery, and it has identical specs to the Sears Diehard Gold battery. The only actual differences are the brand name on the battery case and the fact that Costco charges about $40 less than Sears. Yes, you do have to install it yourself, but that is really easy.

He already had a load test…The lube joint called it a CCA test…It passed. Then they told him it was only half charged, a determination made by the static voltage after the load test.

If you are worried about it, have a shop run a battery and charging system test. This takes about 5 minutes. Places like Auto-Zone will do it free…