Rechargeable AA NIMH Batteries

The AA NiMH rechargeable battery has the same size as the ordinary alkaline AA battery and can be used in the same electrical devises. The AA NiMH rechargeable battery has a length of 1.97 inches (50 millimetres) and a diameter of 0.56 inches (14.2 millimetres). It weighs no more than 0.81 ounces (23 grams). The AA NiMH rechargeable battery has the same electrical output as the AAA NiMH rechargeable battery, but since it is bigger it will last much longer after each recharge.

The AA NiMH rechargeable battery is popular in power draining appliances, since you can recharge it and use it over and over again.

This means that you can save money by not having to purchase new batteries. Just like any other rechargeable battery, the AA NiMH rechargeable battery does however have a limited lifetime and you will eventually need to get new batteries since they can not be recharged forever.

The AA NiMH rechargeable battery has an anode made up by a hydride absorbing alloy. Just like in the NiCd batteries, the cathode of the AA NiMH rechargeable battery consists of nickel. The AA NiMH rechargeable battery is free from cadmium and many consumers has therefore chosen to switch from NiCd rechargeable AA batteries to the NiMH AA rechargeable battery. Cadmium is a toxic metal that is known to accumulate in the ecosystem and increase the risk of cancer. Acute cadmium poisoning can also occur if you are exposed to larger quantities of cadmium and cause acute respiratory tract problems as well as potentially lethal injuries to the liver and kidneys.  

Regardless of which type of battery that you use, you should break its protective sealing. The AA NiMH rechargeable battery might be free from cadmium, but it should still be left intact and damaged batteries should be discarded immediately. Each area has its own system for handling the AA NiMH rechargeable battery when used up. In some regions, you should return the AA NiMH rechargeable battery to the store that sold you the AA NiMH rechargeable battery. In other regions, there are special containers in which consumers can leave their used up batteries.

One important difference between the NiMH AA rechargeable battery and cadmium based AA batteries is that the memory effect is lower in the NiMH AA rechargeable battery. The modern NiMH AA rechargeable battery will also offer you up to three times the capacity of the old NiCd AA battery. The NiMH AA rechargeable battery does however have a higher self-discharge rate than the NiCd AA rechargeable battery. When you have refilled your NiMH AA rechargeable battery, you can expect a self-discharge rate of 5 to 10 percent during the initial 24 hours if you keep your batteries at room temperature. If the temperature increases, the self-discharge rate can increase dramatically.

A NiMH AA rechargeable battery can sustain severe damage if overcharged. During the early years of the NiMH AA rechargeable battery, overcharging could even be hazardous since gas could form inside the battery. Today, a special catalyst within the NiMH AA rechargeable battery will serve to immediately neutralize any gas (2 H2 + O2 ---catalyst--> 2 H2O).