The battery size calculator works out remaining capacity and application load from load current, remaining charge, required duration and voltage. Enter what you have and the relationship is applied straight away, so you get the answer without working through the algebra yourself.
What Is the Battery Size Calculator?
The battery size calculator turns load current, remaining charge, required duration and voltage into remaining capacity and application load.
It is a quick way to get from the numbers you have to the number you need, without setting up a spreadsheet or reaching for a formula.
How the Battery Size Works
Each result follows from the ones before it, and the calculator shows every step, so a surprising answer can be traced back to the input that caused it.
Round your inputs to the precision you actually know, and keep more precision than that in the intermediate steps.
Getting a Result You Can Trust
Run the calculation twice with slightly different inputs. A sensible calculator moves its output in proportion; a wild change points to a unit or a decimal point problem in what you entered.
Write the inputs down next to the answer. It takes a moment and it is the difference between a number you can explain and one you cannot.
A Worked Example
Working through an example, with load current set to 10, remaining charge set to 5, required duration set to 2, the calculator returns application load of 1,000, and remaining capacity of 21.0526, and remaining capacity (remaining capacity pb) of 32.8947. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out remaining capacity?
Enter load current, remaining charge, required duration and voltage. The calculator then works through the relationship and reports remaining capacity and application load.
What does the battery size actually calculate?
It takes load current, remaining charge, required duration and voltage and converts them into remaining capacity and application load using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter load current?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Is the answer exact?
It is as exact as the formula and the inputs allow. The method itself is the standard one for this problem, so the only sources of error are the figures you enter and the precision you ask for.
Do I have to fill in every field?
Only the fields a particular result depends on. If you leave one blank, the results that need it simply show a note instead of a number, and everything else still works.