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.
