First Report - Newly Purchased. This was bought for an infrequently-used pontoon boat.  I tried it on a car battery at home first.  It charged for several hours and then went into "Charge Aborted" mode.  I tried it again and got the same result.  I tried it again with a different car battery and it worked fine, eventually getting a green light and going into "Maintain" mode.  Perhaps the first battery wasn't capable of being fully charged.