Take a special device to determine the capacity of the battery. Then do the following. Charge the battery fully, then discharge it using the current. Be sure to note the time during which it will discharge the battery. Then make the calculation.
Multiply the amperage that you used to discharge the battery for the time it took to complete the devastation, to know the capacity of the battery. The product of these two quantities is the amount of energy that can contain a battery. This way you can determine the capacity of any battery, from the battery of the car, and ending with ordinary battery.
Try to use another method to determine the capacity of the battery. To do this you need a special scheme through which you will be able to discharge the battery through a resistor. Discharge occurs at a voltage not exceeding 1 volt. Then, using the formula I = U/R, calculate the amperage. To measure the discharge time, use a stopwatch or an ordinary clock.
Observe an important condition – the battery must not be discharged completely. To prevent this undesirable effect, use solid state relays. It will allow to disconnect the battery at precisely the moment when the voltage drops to the minimum mark. You can also learn the capacity of the battery without the use of special tools, and the work of any complicated manipulation. As a rule, all the necessary information about the device specified on the label of the manufacturer.
Inspect the surface of the battery. There should be a sticker containing the necessary information required for the operation of the device. If the sticker is worn or missing, you will have to return to the operations described above.