2007 GEM not charging

I have a 2007 Gem car that I just put new batterys in it. I went to charge it and the charger’s red led keeps flashing. I counted only one flash between pauses. One flash on your light-emitting diode, or LED, can mean high battery voltage. There is some type of battery failure, an open circuit or another source of power charging the battery. The batterys are brand new and nothing else is charging them. Anyone else have this problem.