I have recently fitted 2 Hankook batteries, the first was an AGM type to my own diesel the other was a smaller more normal HD Calcium type and I am very impressed with the quality, price and performance of both. Usually when I fit a new battery before fitting I hook my AC Impedance tester up and do a quick check it is okay ,
It has been my general experience with this tester that even the best brand new batteries never score 100% on the life left scale, and generally score about 5% down on the estimated CCA measure. The little Hankook particularly flew through both tests 100% life left and the CCA(EN) estimated by the tester came out at 60 amps higher than the manufacturers CCA(EN) rating