A multimeter is the best way to do this. To check the inverter battery health with a multimeter, first, make sure that the multimeter is turned off. Then, set the multimeter to DC volts and touch the red lead to the positive terminal of the battery and the black lead to the negative terminal.
Utilizing a digital multimeter, proceed to check the battery's voltage. This step should be done with the inverter turned off and all connected loads disconnected to ensure an accurate reading. Attach the multimeter's positive (red) probe to the battery's positive terminal and the negative (black) probe to the negative terminal.
Another way to test your inverter without a battery is to connect it to a load (such as a light bulb) and then measure the AC voltage at the output terminals with an oscilloscope. If there’s no AC voltage present, then again, there’s probably something wrong with your inverter.
You can directly check the battery voltage with a multimeter from the battery terminals, which is easy to use and inexpensive to purchase. Here’s how to measure voltage: Turn off the inverter and disconnect any AC power inputs. Set your multimeter to voltage measurement mode, usually marked with a “V” symbol.
Attach the multimeter's positive (red) probe to the battery's positive terminal and the negative (black) probe to the negative terminal. A healthy 12V inverter battery should display a voltage in the range of 12.6 to 12.8 volts. Readings below this range may indicate a need for recharging or a potential battery weakness.
Here’s how to measure voltage: Turn off the inverter and disconnect any AC power inputs. Set your multimeter to voltage measurement mode, usually marked with a “V” symbol. Attach the black multimeter probe to the battery’s negative (-) terminal. Attach the red probe to the positive (+) terminal. Note the voltage reading on the multimeter display.