mAh stands for milli Ampere hour or milli Amp hour. It is a measure of a battery's energy storage capacity. If you think of a battery as a small fuel storage tank, which in a sense it is, mAh a measure of how much 'fuel' the battery holds. (This is roughly comparable to using gallons to measure how much fuel a gas tank can hold. The more gallons of capacity, the more fuel the tank can hold.) With a battery the higher the mAh rating the more electrical energy it can store.

While it is useful to think of mAh as being the rough equivalent to gallons, the analogy is not a perfect one. Different types of batteries use different methods to measure mAh so comparing the mAh rating of one type of battery, say an alkaline battery to another say an NiMH battery, is not always meaningful. However, in general, the mAh rating of a battery is a quick way to compare the relative energy storing capacity of one battery to another battery of the same type.

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Better Battery 1 2 Hp

Can I substitute a higher mAh battery for a lower one?

If the batteries are of the same type, i.e. both are NiMH or both are Lithium-ion, then you can use a higher capacity (i.e. higher mAh) battery instead of the lower one. The reverse is also true. Using a higher mAh rated battery will allow the device to run longer on a charge. So a camera should take more pictures and a music player can play more songs.

Keep in mind that it will take a little longer to charge a higher capacity battery. (Staying with the fuel tank analogy from above, it would also take longer to fill a 20 gallon gas tank than a 12 gallon tank).

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What is the shelf life of a NiMH battery?
You probably mean to ask: What is the self discharge rate of a NiMH battery? The rate of self discharge for any battery depends on the temperature at which it's stored. Stored at 70 degrees F (20 C) NiMH batteries will lose up to 40% of their charge within a month. If they are stored at a higher temperature, they will self discharge at an even higher rate. NiMH batteries stored at a lower temperature self discharge at a lower rate (Self discharge chart available soon).
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