Mmr1

2013 Glk 350 70000 miles , Interstate AGM battery 18 months old. Drive 1 hr a day. Battery doesn’t seem to be kept 100% charged by Glk , I can put it on one of several chargers at any time and they say 80% charged and take up to 3 hrs to charge it. Voltage of battery might be 12.25, and Cca about 110 CCA lower ! than the charger will get it. I’m thinking the alternator just won’t keep it like it should be. Car starts fine , I’m just wondering if this is normal.

Charging it with a CTEK it gained 70 Cca I think that’s a lot .

i never use stop start, that’s the first thing I shut off every day

i just charged it CCA went up 110 a !

Plutoe

get a load test biff

Mmr1

I did biff, that’s the first thing I did when it was 100a lower on CCA it passed.

streborx

I have read, but have no confirmation, that charging systems have been designed this way for fuel economy reasons. Under normal operating conditions, the battery isn't charged more than 80% because there's no functional benefit to topping it off. I haven't checked this on my G550, but I was surprised to find that my '22 BMW X7's battery took a couple hours of 10A charging from my Noco charger after returning from a 250 drive.