Yesterday I replaced the original main battery in my 2014 model year GLK 3.5L Gasser. The battery was made in June of 2013 and I picked up the GLK, new, in July or August of 2013.

As expected, the test results show significant signs of degradation due to use and age. Having said that, the battery never failed to start the engine even one time and never even caused a slow crank situation. I could have continued using this battery until: who knows? Obviously, one day, it would have let me down. I just don't know when.

After removing the battery I put it on the charger for 24 hours. The test photos are from today after taking it off the charger. Ambient temp. around 50F / 10C.



calculated CCA well down from original 800.

State of Health, after a full charge, only 61%.

A lot of starting success has to do with having a well maintained vehicle that starts easily.

BTW - How often do you find the carbon pile tester useful? My 250 Amp tester went to storage because my rather old on car analyzer was a lot more convenient and gave enough information.

My 7 year old original AGM tested about 580 and I replaced it . It has gotten down to -20 in chicago and I was worried about winter drain. In a mild climate your old one is ok for now , but yes , for how long . A charger with a restore cycle might add 25 amp . It’s still good for an emergency jump !

I agree - a well-maintained vehicle helps a lot, but maybe more so with older vehicles.

hmmm... not sure I found the tester all that useful, in the big scheme of things. Just have a bad habit of collecting tools and test equipment thinking I'll definitely need them at some point.

I think I would have been in trouble a long time ago, battery-wise, if I lived in Canada. There are four seasons where I live now (wouldn't have it any other way) but winters keep getting milder and shorter. A white Christmas is pretty much a thing of the past.