Battery dieing and over charging

Hey guys, novice mechanic here. I've got Craftsman LT 1000 17.5 hp briggs. Recently the battery has died and I replaced it . Now the new one won't keep a charge. I checked voltage with mower off and it was just over 12. When I cranked it up it went to about 14 but I noticed it climbing. It got over 16 in matter of a minute. It appears their back voltage being induced does that seem possible or accurate? Thanks for any help.