Rechargeable Battery Problem

Yes NiMH rechargeables get hotter during charging than Nickel-Cadmium ones do. This is normal. The warmer they get, the nearer they are to being fully charged. Some "smart" chargers use this fact to decide when the batteries are fully charged. Cheap basic ones just rely on charging for a fixed time. Either way, it's normal for them to feel warm when you get them out of the charger.

There is also an low temperature issue. People using them in cold conditions find that even a fully charged NIMH battery will weaken at low temperatures, say below 4 degrees C or 40 degrees F, so that you cannot get full voltage. One solution is to put them in in a charger and charge them for 3-5 minutes to warm them up a bit, after which they will give normal performance, at least until they cool down again. (In actual fact, all batteries, rechargeable or not, do this to a certain extent.)

At normal room temperature, NiMH rechargeable batteries will generally lose about 1% of their charge per day. Higher temperatures will increase this loss, and lower temperatures (40-60F) will reduce this daily loss. This "shelf life" is less of a factor if you use them within the first five to ten days after they are charged.

One of the best ways to ensure that NiMH rechargeable batteries will last as long as possible is to use them often. The more they are charged and used, the longer NiMH rechargeable batteries will last. Whether discharged or not, NiMH rechargeable batteries should be charged at least every sixty days.

Thanks for the information, it really helped!