Just replaced my wife’s GM’s H6/group 48 this morning, Costco to Costco.
The old is 3 years old and still good, so why?
Well, on the voltmeter of the car, I think the charging is intelligent. So when really cold and battery not tip top, volts climb to over 16. I don’t like that. Another clue? Mpgs, gallons consumed, etc, reset on its own.
In the summer we can witness the voltmeter at 12…imho this means the car decides to not charge. Meaning beginning of the trip it’s like 14 then 2 hours later on highway 12v. Restart car back to 14v.
Here are the tests on a 730CCA H6, 3 yo and brand new. Keep in mind 730CCA is at 0F. It was about 40F and 3 yo is 660CCA and not fully charged (should be, as it’s driven daily).
New
The only time I didn’t DIY tech didn’t even connect the vent tube so sloppy