When shopping for power-tool batteries you may have noticed a number on the battery representing Ah or AMP HOURS. This is directly correlated to the amount of life the battery will have during its time in use. Think of it in terms of gas tanks on a car; some may have 30 gallon tanks while some have 20 gallon tanks. The only difference is the amount of fuel. So if you have a 3 Ah battery, it is safe to say it will have a longer life then a 2 Ah battery. Think of it as the 30 gallon tank yielding more fuel.