After you have decided which batteries you need an essential quality test on incoming batteries from your supplier is to check their voltage. Then you’ll quickly and easily know that they hold the required amount of power.
Batteries are meant to store a certain amount of voltage and this can be tested by connecting it to a multimeter (or voltmeter).
You’ll set up the multimeter and select the DC voltage setting (a V with 3 dots or a dash above it or DCV or something similar).
Most digital multimeters used today will automatically recognize the battery’s voltage range, so all you need to do is hold the positive and negative probes to the correct terminals - in this case, positive is red and negative is black.
The battery’s voltage will appear on screen and should, if the battery is full or almost full, be around the correct voltage. So, for a 9 volt battery, you should be seeing a value of 9 volts or just under.
If the batteries you receive from a supplier do not reach the required voltage, they fail the test and you can take action to solve the issue.
Other tests will be required to assess battery-safety, such as for Li-ion batteries which are due to be shipped.
Watch a video explaining how to test battery voltage using a watch button cell as an example here:
https://youtu.be/VdTQkPhmcO4