Battery Capacities

• Nickel-Metal Hydride (NiMH) rechargeable batteries have the highest capacities for these types of batteries. They have a total capacity up to 1,000 milliampere hours (mAh) for AAA batteries and up to 2,700 mAh for AA batteries. Low self-discharge NiMH batteries (LSD NiMH) have a total capacity of up to 800 mAh for AAA and up to 2,000 mAh for AA. Nickel-Cadmium (NiCd) batteries have a total capacity of up to 350 mAh for AAA and up to 1,000 mAh for AA.
  
  

Overcharging

• Rechargeable batteries, especially NiMH batteries, are sensitive to continuous overcharging, or leaving the batteries on the charger after they've been fully charged. Many chargers do not stop charging batteries when they are full, placing the responsibility for monitoring the charge on the consumer. Continuous overcharging can greatly shorten the life of a battery, even to a few months.
  
  

Prevention

• Some battery chargers not only charge the batteries but also switch to a trickle charge or stop charging automatically to prevent the batteries from overcharging. You can also time your battery charges, depending on how long the specific battery is supposed to charge, to prevent overcharging.