How to calculate amp hours (Ah) of a battery bank?

In the market, there are usually multiple capacities of batteries exist, that starts anywhere from 7Ah to 200Ah with different year range of warranty available. It can be 24 months or 36 months or 60 months, etc. Depending on battery capacity and warranty, the price of each battery may vary. Here, the main question is that, how to calculate amp hours (Ah) of a battery bank?

Because we usually choose a battery based on technical specs that’s written on battery box. But we have to verify and calculate the exact amp hours (Ah) of a battery bank before buying in order to run many appliances like printer, washing machine, microwave oven or a dishwasher.

Don’t worry! I will give you an easy calculation to calculate the exact amp hours (Ah) of any battery capacity and It doesn’t matter if it is a lead acid battery or lithium ion battery as these calculation works on both the battery types. Let’s continue reading… Let’s understand some technical terms while calculating the amp hours of a battery.

1. Power: Power is denoted in watts. (i.e. P=watt)

2. Meanwhile Energy is denoted as a watt hour (i.e. E= Watt hour)

Formula of Amp Hours Calculation

Formula of Energy is: E = P * T

Whereas, E stands for Energy, P stands for Power and T stands for Time.

E = Watt * Time

   = VA * Hr.

Ah = E / V  

     =  4400Wh/12V

     =  366Ah

Here, 4400Wh is required storage as per our battery capacity calculation in our other post.

Hence, you can buy any rating of battery and verify if the said output of the battery is 366 Ah. Whereas, when you choose 150Ah battery, then you might need around 2 nos. of batteries to get the 366 Ah output and finally, If you choose 120Ah battery, then you might need around 3 no. of batteries.