I suspect it's really doing a CA test, unless you have a 0 ℉ freezer to keep the battery in for a while before testing, or you make sure to use it on winter days that happen to be 0 ℉, which would match an official CCA test. Or maybe the reduction in CA with decreasing temperature has a known formula, and the tester measures the ambient temperature and corrects it to 0 ℉ with math. I don't know if that's practical.
It has several other options, including CA (Crsnking Amps) though I’m not sure my battery specs that. Would there be a general factor applicable to CCA that would ballpark the CA? that said, testers of that ilk typically offer CCA measurement; they employ some method to make measurements at other than zero?
I wonder why you care about crank amps for a Prius? The 12V does not crank anything, it just powers up the ECU… Yuasa is the best I have tried, but I also use ctek attachment and recond them 12V every quarter year regardless. Dead aux batteries are the worst.
That's not the first time that's been wondered in this thread. Seems like every time it gets wondered, someone has to say again "because there are common tools that let you compare a battery's present cranking amps to the cranking amps on its label, and that's an easy way to get an indication of the battery's present condition". Doesn't need to have anything to do with 'cranking' needs of the car.
