How to measure battery cells

How do you measure a battery's capacity?

A battery’s capacity can be estimated relatively accurately using a set of measurements and some complex math, but the most simple way to measure a battery’s capacity is to measure the power going into or out of the cell. Power going into the cell would be charge testing and power coming out of the cell would be considered discharge testing.

How do you test a battery cell?

To test the capacity of a battery cell, you have to fully charge and fully discharge the cell while precisely measuring the energy in at least one direction. Also, being able to test a battery’s true capacity gives you leverage when buying battery cells.

How do you know if a battery has a lower capacity?

There is no way to directly ascertain a battery’s capacity using its ISR. But if a cell’s IR is much higher than other cells from the same batch, you can bet it will have a lower capacity. The good news is that you can get a 18650 or 21700 cell charger/tester that charges the cells and tests the capacity.

How do you measure cell capacity?

The cell capacity is dependent on the charge voltage, the discharge rate, and the end point voltage. The charge voltage and end point voltage also affect the cell lifetime. This means there is no one 'right' way to measure the capacity of a cell, as both lifetime and capacity are desirable, but are in conflict.

How do I estimate battery capacity using a multimeter?

To estimate battery capacity using a multimeter, follow these steps: Measure the OCV using the multimeter’s voltage setting. Compare the measured voltage with the manufacturer’s voltage vs. state of charge (SOC) chart. Estimate the battery capacity by multiplying the rated capacity by the SOC percentage obtained from the chart.

How do you calculate the remaining capacity of a battery?

Estimate the remaining capacity: Multiply the SOC by the battery’s rated capacity to estimate the remaining capacity. Let’s assume we have a 12 V, 100 Ah lead-acid battery, and we want to estimate its remaining capacity using the OCV method.