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What is the capacity of a battery?

What is battery capacity?

Shop for Cordless Screwdrivers

Battery with voltage bolt Battery capacity refers to the amount of electrical charge a battery can hold.

The larger the battery’s capacity, the longer it can run before needing to be recharged.

Amp hours

Detachable battery for a cordless screwdriver Battery capacity is measured in amp hours. Each battery is given an amp hour rating which is written as a number followed by the letters ‘AH’ or ‘Ah’.
Stop watch This number tells you how many amps of electrical charge the battery can deliver for the duration of 1 hour.

Typically, for cordless screwdrivers, battery capacity ranges from 1.1 AH to 2.0 AH.

  Wonkee Donkee says; For example: a battery with am amp hour rating of 2.0 AH can deliver an electrical charge of 2 amps for the duration of 1 hour, or 4 amps for 30 minutes, or 8 amps for 15 minutes.
Cordless screwdriver You can work out how many amps are being used by looking at the tool’s battery voltage and capacity.

For example, the cordless screwdriver on the left has a 4 volt battery with an amp hour rating of 1.5 AH.This means it can deliver an electrical charge of 1.5 amps for the duration of 1 hour, or 3 amps for 30 minutes, or 6 amps for 15 minutes and so on…


If the tool runs for 15 minutes at full power before the battery runs out, then we know that at full power, it’s using 6 amps.

Capacity summary

yellow and black 10.8 volt spare cordless drill driver battery with a red circle around the 1.5 AH symbol A battery with a higher Ah rating has a larger capacity and will run for longer between charges compared to a smaller capacity battery doing the same task.
Pile of gold coins However, a tool with a larger battery capacity is likely to be more expensive.

Wonkee Donkee Tools