Charging A Motorcycle Battery With A Car Charger – How to Guide

Before you can decide whether you can use a battery charger designed to charge an automobile battery on your bike you need to understand a couple of simple things.


The majority of all car batteries are twelve-volt devices. Car battery chargers are designed to produce the proper voltage and charge for a twelve volt battery.

The motorcycle you have may have a twelve volt battery but it also may have a six volt battery. Make sure you know the voltage of your battery before you charge.


Motorcycles that have been built in the last decade will commonly have a sealed battery. The sealed battery protects you from battery fluids being leaked if you happen to have an accident.

The sealed battery can be problematic when you are charging it. Gases can build up inside the battery and cause the housing of the battery to crack, rendering your battery useless.

To charge sealed batteries safely, and protect the integrity of the battery, you need to use an automatic charger. An automatic charger has sensors that tell it when the battery has reached full capacity, and usually when a battery has a problem.

Charging Your Motorcycle Battery With A Charger Designed For Cars

The main problem with charging your motorcycle battery with a charger designed to be used on automobiles is that the charger will put out more current than your battery needs and thus render your battery useless piece of rubble.

Connect a test lamp to your battery

If the only battery charger that you have available is one designed to be used on a car or truck then you can try this trick.

Connect a test lamp to the positive side of your battery terminal using the jumper clamp on the test light. This allows the current that is being provided to your battery via the charger to be dispersed to the battery and the test lamp.

That reduces the current that is being sent to your battery and may save the life of your battery. You can even connect more than one test lamp to divert more of the charge from the battery and keep your battery safer.

Do not use a car charger for an extended period of time

It is better to charge your battery in short increments than to hook your battery up to a car charger and leave it for days, or weeks. A 2 amp charge can be kept going for about 10 hours, and no longer.

Do not set your battery charger up and allow it to stay connected to your battery unless you have specifically purchased a trickle charge battery charger designed for use on motorcycles, ATVs, lawn equipment and such.

Keep a close eye on the charge

To make sure that your car battery charger does not damage your motorcycle battery you need to keep a close eye on the device. The newer car battery chargers have indicators that will tell you how much charge the battery it is connected to is at.

You want to keep a close eye on the amount of charge your battery has so you can disconnect the charger as soon as your battery reaches 100%.

Use a charger that has 6 volt or 12 volt capabilities

A safer way to use a car battery charger to charge your bike battery is to get a newer charger that can be switched from 12 volt to 6 volt.

Some of the newer battery chargers can even determine what voltage your battery is and make the adjustments to the battery does not get overcharged or overheated during the process.

You must still keep a check on the charger to determine when to disconnect your battery. The newer chargers have indicator lights, and many of them have safety features that will shut them down if the battery they are connected to should overheat, or be in danger of being over charged.

Final Thought

The best way to charge your motorcycle battery is with a battery charger designed for specific use on motorcycles. Car chargers are meant to power larger batteries.

Alston Seymour

A Harley-Davidson Motor Company certified Master Technician and avid biker, I love to write about everything and anything related to biking.

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