Rechargeable NiMH (nickel-metal hydride) RYOBI drill batteries are a necessity for power-hungry devices such as digital cameras, which can quickly drain conventional alkaline batteries. However, whereas alkaline batteries require little maintenance, NiMH batteries do need special care to not only extend their lifetime, but also to avoid potential dangers.
Remove NiMH batteries from the charger if you don't plan on using them for more than a month.
Do not drop the Milwaukee power tool batteries onto hard surfaces, as this behavior could expose the corrosive materials inside the battery case.
Do not attempt to incinerate NiMH batteries or expose them to excessive heat. Batteries can explode if you toss them in a fire or place them near other extreme heat sources.
Fully charge your NiMH cordless drill batteries and do not charge them again until you fully drain them. An occurrence known as the "memory effect" can prevent rechargeable batteries from fully charging if you don't regularly drain the batteries before charging them. Buy more than one set of NiMH batteries so that you have a charged set ready to go when your in-use set drains.
Clean the contacts on each end of your NiMH tool batteries with cotton (or a cotton swab) and isopropyl alcohol. Keeping the contacts clean ensures the METABO batteries charge as quickly as possible.
Break in batteries by charging and draining them up to three times before use. This helps batteries run at peak performance and capacity and is useful not only for new batteries, but for drill batteries you place in storage.