A motorcycle's battery amp-hour rating (AH) is measured by its ability to sustain a one-amp electrical current for one hour. If maintained properly, a 12-volt battery with a 7AH will provide enough power to start your motorcycle's motor and power its lighting system for three to five years. A failing battery, however, is often detected by an inability to start the motor, accompanied by a distinct clicking sound. Testing the battery's voltage, then putting an electrical load on it, can help determine the battery's condition, often without having to remove it from the motorcycle.
Static Voltage Testing
Step 1 Remove the motorcycle's seat or battery cover, using the ignition key or a socket wrench.
Step 2 Set your multimeter to a direct current (DC) scale, using the setting knob on the multimeter's face.
Step 3 Touch the multimeter's red probe to the battery's positive terminal, indicated by a plus symbol. Touch the black probe to the battery's negative terminal, indicated by a minus symbol.
Step 4 Take note of the battery's voltage displayed on the multimeter's screen or gauge. The battery should have a voltage of 12.1 to 13.4 volts DC. Remove the probes from the battery, black probe first followed by the red probe.
Step 5 Connect the battery to an automatic battery charger if the multimeter indicates a voltage of less than 12.0 volts DC.
Retest the battery's voltage, using the method shown above. Replace the battery if its voltage is below 12.0 volts DC.
Load Testing
Step 1 Set your multimeter to a DC scale, using the setting knob on the multimeter's face.
Step 2 Touch the multimeter's red probe to the battery's positive terminal, indicated by a plus symbol. Touch the black probe to the battery's negative terminal, indicated by a minus symbol. The multimeter should indicate a voltage greater than 12.1 volts DC.
Step 3 Turn the motorcycle's ignition switch to the "On" position to place an electrical load on the battery. Do not start the motor.
Step 4 Take note of the battery's voltage displayed on the multimeter's screen or gauge. The battery should have a minimum of 11.1 volts DC while loaded. Remove the probes from the battery, black probe first followed by the red probe.
Replace the battery if its voltage is below 11.1 volts DC while loaded.
Items you will need: Ignition key, Multimeter, Automatic battery charger
