I've had a lot of grief trying to keep the battery charged. I changed from the Battery tender Junior to the charger/tender model, but no avail. I've read on various threads that you need to keep the doors locked to prevent small current drains from messing with the charger's circuitry, but that hasn't worked either. latest symptom was charger red/green lights flashing simultaneously, and ceased charging. Then I got a 9V cig lighter device thinking I'd just disconnect the cables completely and charge the battery disconnected. But the security system freaked out with the 9V trickle, started cycling and flashing quickly. Not sure why mine is so problematic; others seem to have no problem!