6 Pack battery charger in Ryobi Posted February 4 · Report reply 7 hours ago, Paddy said: The way these new batteries are you can charge them up to full capacity, take them out of the charger and let them sit there for 6 months and they will still have charge in them to use. There's no reason to leave them in the charger after they've charged up if you're not going to be using them for a few months. You can top them up every 3 or 4 months too if you like but these new lithium ion batteries can hold their charge for a long time when not being used. The older ni-cad batteries used to drain down if they weren't used This...for better or worse I've got more batteries than I know what to do with. My DeWalt 12v Max batteries sit idle for months but are ready when I need them, and some are 8 years old. My 8v Max gyro drivers see the batteries charged maybe twice a year.