How to Identify a 6-Volt or a 12-Volt Tractor

by David Sandoval
tractor image by Alison Bowden from

Most vehicles with an internal combustion engine require a battery to provide electrical energy for starting. While most automobiles tractors, and lawnmowers make use of a 12-volt battery, not all do. If the battery has died on your tractor, purchasing the wrong battery will not only be a waste of money; it may also damage your tractor's electrical system.

If you do not have a copy of the owner's manual for that tractor, there is a relatively simple way to tell whether the electrical system produces 6 volts or 12 volts--by examining the installed battery.

Step 1

Open the battery compartment and find the battery.

Step 2

Count how many battery vents the battery contains. Battery vents are covered by small round plastic caps at the top of the battery.

Multiply the number of battery vents by 2.1 volts. This will give you the approximate battery voltage (and by extension, the electrical system voltage as well).


  • A fully charged battery's voltage is slightly more than 6 volts for a battery with 3 vents. A fully charged battery's voltage is more than 12 volts for a battery with 6 vents. This is because the voltage differential for each battery cell is equal to 2.1 volts rather than 2 volts.

Items you will need

  • Tractor with installed battery
  • Pen or pencil
  • Paper

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