INTEC Systems

How much energy can your battery store?

Battery capacity is measured in Amp Hours (e.g. 17AH). You need to convert this to Watt Hours by multiplying the AH figure by the battery voltage (e.g. 12V). this is just the simple calculation below

X (Battery size in AH) x Y (Battery Voltage) = Z (Power available in watt hours

For a 20AH, 12V battery the Watt Hours figure is 20(X) x 12(Y) = 240 WH (Z)

This means the battery could supply 240W for 1 hour, 120W for 2 hours or even 2w for 120 hours i.e. the more energy you take, the faster the battery discharges.

However you are never really able to take all the power from a battery as once the voltage drops below your equipment’s requirements it will no longer be able to power it. There is a simple rule of thumb for this but please check your battery’s specifications to make sure.

Lead acid battery’s will give you around 50% of their rated power. (i.e. a 10Ah battery has 5Ah of usable power)

Li-ion battery’s will give you around 80% of their rated power. (i.e. a 10Ah battery has 8Ah of usable power)

A common question that people ask regarding the battery’s is,