How Much Voltage Is a Lawnmower Battery?

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Not all lawn mowers use the same voltage battery.

Lawn mowers that contain an electric starter contain a battery. A battery is a key component for the operation of a lawn mower; without this battery, the lawn mower will fail to start. Depending upon the lawn mower's electrical system, the mower will require a battery that can provide either 6 or 12 volts of electrical energy.


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Lawn Mower Battery Function

Lawn mower batteries are used to provide electrical power to turn the starter mower and initiate the ignition process. A lawn mower battery is a small lead-acid battery, and may be purchased at many hardware or auto parts stores.

Electrochemical Processes in a Lawn Mower Battery

A lawn mower battery contains several individual battery cells. Each of these cells contains a positive electrode that is made out of lead oxide and a negative electrode that is made of lead. Each of these electrodes is immersed in an acidic electrolyte solution. The chemical reaction between the two electrodes produces a voltage differential of 2.1 volts per battery cell.


6-Volt Lawn Mower Batteries

A 6-volt lawn mower battery contains three battery cells wired in series with each other. These batteries provide 6.3 volts of DC electrical energy. If a 6-volt lawn mower battery is not clearly labeled, you can quickly identify the nominal voltage of this battery by counting the number of cell vent caps at the top of the battery case. Since the battery contains three cells, this battery will contain three vent caps.

12-Volt Lawn Mower Batteries

A 12-volt battery has six cell vent caps. The vent caps on this battery are yellow and are placed at the top of the battery.

A 12-volt lawn mower battery contains six battery cells wired in series with each other. These batteries provide 12.6 volts of DC electrical energy. A 12-volt battery will have six battery vent caps at the top of the battery case. These batteries are more commonly used in electric-start lawn mowers than 6-volt batteries are.