My factory truck batteries are now 5 1/2 years old and seem to be doing fine. My question is if I should be proactive and replace the batteries, or wait until there are signs of impaired performance.

My dad would always replace the battery at a maximum of four years.

 

If it ain't broke, don't fix it. That said! take to a parts store, Wally world, or bout anyone that sells batteries. They probablly have a free bty chec. Test the batteries separatelly with one disconnected from the other. Now you don't have to worry. If one fails then replace both and keep the good one for another vehice or sell. Don't use a old and new battery together.

 

X2 on IIABDFI. I got 8 years out of one factory battery with no sign of weakness, usually about 5-6 yr though.

Load test it and find out. You could check the terminal voltage at rest, and disconnected. Anything under 12.25 is not going to last much longer but would get through a summer. I would replace if going into winter.

Cya

 

Without a load and disconnected, one battery was 12.62V and the other was 12.65V.

 

The load test will be more accurate but I wouldn't have a problem with those numbers unless you're noticing weak prformance. Keep the cash for now and start shopping for your best deal in the fall. If you park inside or live where it's warm I'd bet you'll get another year or more out of them.

Theres no doubt the're not new anymore (13.013.2V new) but might as well get the use out of them before you replace them. JMHO.

Cya

 

It also depends on how big a deal it is if you can't start someday. If you don't mind getting a jump start and buying new batteries on the way home, let them go longer. If not starting is a big hassle to you, then buy them as they get old - watch for a sale, etc.