nlspace wrote: ↑Tue Jan 25, 2022 1:33 pm
If her 2018 battery is really low capacity, then it might not complete a full 20 hr capacity test. But it would be interesting to hear how degraded it is.
FLA battery failures are really common these days with fewer trips and miles driven. Just last night i helped a neighbor with a jump start for this truck; he thought his alternator was bad, but it was putting out 68Amps into his weak 2 yr old battery. Sitting around without being driven or kept fully charged with a trickle charger, is a recipe for a dying 12V battery.
When the auto store does it's load test, the battery voltage will sag all the way down to 9V but it produces enough power in that short time that in theory, it would start a car according to them. Capacity wise, could you keep cranking on the battery if the car didn't start on the first or second try, probably not. I have tried to do a 20 hour test on it, it never makes it. Basically, it scores around 8AH of capacity, which is way below what the new battery rating gets (I don't remember if it was 31AH or 44AH for the OEM battery). I'm also running my test indoors where it's nice and warm, not freezing outside, so that probably offsets my numbers a little as well. I still keep the battery though, just in case it's needed for temporary service.