Ordinary 12-volt lead acid batteries are reliable and usually last for three or four years in a car or motorcycle before you need to replace them. Fully charged 12-volt batteries will show about 12.6 volts on a meter. You may need to discharge and then recharge batteries that have been overcharged or lose their charge rapidly. Discharge a 12-volt battery slowly to equalize the sulphate on the lead plates. Allow a battery to discharge on its own, or discharge it slowly by connecting a car headlamp to the battery.
Things You'll Need
- Volt meter
- Car headlamp
- Electrical wire
Set a volt meter to its 12-volt scale.
Connect the positive (red) terminal on the volt meter to the positive (+) terminal on the battery. Connect the ground (black) terminal on the volt meter to the negative (-) terminal on the battery. Note the voltage displayed on the volt meter.
Cut two lengths of electrical wire long enough to reach from the battery terminals to a car headlamp. Strip once inch of insulation off each end of the electrical wires.
Connect the negative (-) side wire from the car headlamp to the negative terminal on the battery by inserting the wire between the volt meter clip and the battery terminal. Repeat for the positive (+) side of the battery and headlamp.
Monitor the volt meter. Disconnect the positive (+) wire and then the negative (-) wire attached to the battery when the battery is discharged to no less than 11 volts. Recharge the battery before use.
Tips & Warnings
- Keep battery terminals clean and free of corrosion and oil for maximum performance.
- Never discharge a 12-volt lead acid battery below 10.5 volts. Severe damage to the battery lead plates may result.
- Discharge a 12-volt battery in a well-ventilated area.
- Always use protective eye wear.
- Avoid touching the battery terminals. Electrical shock is possible. Wear gloves when connecting battery terminals.
- Never touch any fluids leaking from a lead acid battery. The acid can burn your skin.
How to Clean the Discharge on a Car Battery
It may just stop you in your tracks. That stuff on the battery in your car. A result of gasses created by...
How to Charge a 6-Volt Positive Ground Battery
Although most vehicles use a 12 volt battery that negatively grounded, some vehicles that were still in use as of 2010 use...
How to Wire a 12 Volt Electrical System in an RV
A well-thought-out 12-volt electrical system in a recreational vehicle, or RV, allows for extended periods of remote camping and the reliable starting...