No matter if you have the Black+Decker battery charger or any other device, you should check its state on a regular basis. Having a voltmeter at hand, you can easily check your power appliance. Here’s a short action list: 1. Get the voltmeter ready. Install the test probes, ensure the power supply, select the “DC” measurement and put the indication slightly bigger than the nominal charger voltage. 2. Plug the charger into an outlet and connect the voltmeter to it. The red probe goes to the positive contact and the black to the negative one. 3. Check the voltage indication. An indicator on the left side means a non-working charger or incorrect probes placement. The indicator on the right side means the appliance is working. The reading will show how much charge it conveys. For sufficient feeding of the particular power bank, the voltage should be equal or higher than the cell’s indication.