I bought a 12 volt battery load tester. It clips to the posts, and first reads voltage. You then press the start button and it tests the battery under a load. Apparently, it doesn't work if the battery has over 13.1 volts. When I took them off the charger, couple batteries had 13.7 volts and one had 14.1 volts. All three are brand new batteries, group 31's. The tester worked ok after the voltage dropped down to 13.1, and they tested good. Is it normal for a battery to have that kind of voltage while it's on the charger? Thanks.