If you have an electric meter, it shows energy consumed in Watts per hour. This energy has an amount, Joules that is. But in a battery there is energy stored that also has an amount. So it should be in Joules as well. But the unit is different: Ah,(or mAh).Why is that and what is the difference between these two u
In: Physics
A Watthour is not a Watt divided by an hour but a Watt times an hour. Wh = W x h not W / h
Watts are already joules divided by seconds. So by multiplying the watts by a unit of time again you end up with measure of the same thing as Joule was originally. (You can get back to joules by dividing by 3600 the number of seconds in an hour)
Watts in addition to be being joules per second are also volts times ampere. W= J/s = VA
So a what hour is a Volt times Ampere times hour. Wh = VAh
so to get from Ampere hours to watt hours you just need to multiply them by the voltage.
Two batteries with the same mAh but different voltage will have different Watthours.
If you know the Watthours a battery claims to have and know the voltage you can just divided the Watthours by the Voltage to get the Amperhours.
Latest Answers