I have a Ryobi 6 volt HP61 cordless drill, without a battery charger. It takes a 440001 ryobi 6 volt battery charger. I can not find one in searching the internet because they all say this charger has been discontinued. I have a plug in 12 volt adapter that I plugged in to the drill. It charged the battery, but I was afraid to leave it in very long as I don't know if I will ruin the 6 volt battery. ANYBODY KNOW?. THANKS. JOHN.