How To Test and Change a Motorcycle Battery

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A flat battery that cannot start your motor renders your motorcycle useless. This problem is especially common if the motorcycle is seldom ridden or when it is pulled out of storage at winter’s end.

However, it is simple to test and, if necessary, change your motorcycle battery. Just follow the steps below.

Why do you need a healthy motorcycle battery?

When you’re riding your bike, the motor powers the alternator which then usually generates sufficient electricity to run all the electrical equipment, such as the headlights, indicator lights, and your motorcycle GPS.

However, the alternator cannot provide the initial cranking amps to start your motorcycle’s engine because it generates no electricity until the engine is operating.

To start your motorcycle’s engine, you require the power stored in your motorcycle battery. Also, when the engine is running slow, the alternator cannot provide sufficient power to run all the electrical devices. The motorcycle battery acts as a storage device for electricity that can be used during these situations.

While you’re riding, the alternator will recharge your motorcycle battery. This ensures your battery has enough power to start the engine the next time you need it and so it can operate as an energy reserve.

However, if you don’t ride your motorcycle for long enough to charge the battery or if you don’t ride regularly, there is a danger the battery will discharge.

When your motorcycle is not ridden for a long time, and the battery is not charged using a battery tender or battery charger, chemical reactions within the battery can lead to a complete self-discharge.

Also, an older battery may no longer be capable of holding enough stored energy to start the motor. A flat battery cannot start your motorcycle’s engine or provide power to its electrical components.

Using a portable jump starter offers a temporary solution to this problem. However, if the battery is faulty, the only long-term solution is to exchange it for a new one. To assess whether your motorcycle battery requires replacing, you must test it.

Motorcycle Battery

Testing and checking your motorcycle’s battery

Your motorcycle battery can easily be tested using a voltmeter. Voltmeters (multimeters) can be set to a specific range of voltage. If there is a 12V setting, this is the best one to select. Otherwise, choose the 20V setting.

Don’t test the battery immediately after charging or riding your bike. This will not test for a loss of charge. Leave your battery for at least an hour after charging.

Before testing, turn on your motorcycle’s ignition and ensure that the headlights are operating. Leave them on for two minutes and then turn off the ignition. This will enable a more accurate reading.

When attaching the voltmeter leads to your battery, ensure that you attache positive to positive and negative to negative. If the battery is operating properly, this should provide a reading between 12.4V to 12.6V. A reading below 11V indicates that the battery requires charging or possibly replacing.

Next, you must test what happens to the battery’s voltage when the motor is started. With the voltmeter leads attached, start the engine.

If the battery is working optimally, the voltage will drop to around 10V. If it drops below 9.6, the battery probably needs replacing because its capacity is too low.

Before you rush off to buy a new motorcycle battery…

If your motorcycle battery failed to provide healthy voltmeter readings, it probably requires replacing. Before you do so, examine the battery for common problems that can be fixed. The following tasks are best performed inside a garage that is well illuminated by shop lights.

Sometimes, battery terminals can become corroded and this will affect the battery’s operation. If the terminals are cleaned with fine sandpaper or a wire brush, this may resolve the issue. Following cleaning, protect the terminals from future corrosion by applying grease.

Older lead-acid batteries may have an electrolyte level that requires monitoring. Horizontal lines at the top of the tray indicate a maximum and minimum level for the electrolyte inside.

If the level is too low, distilled water should be added up to the maximum level. Such older batteries also employ a vent to release pressure, and it is important to ensure that the vent is not clogged. More modern Gel or lithium-ion batteries are “maintenance free”, so you cannot add water and there are no vents.

Where there are signs that the battery’s casing is cracked, the battery must be removed immediately so that the battery acid does not cause damage to your motorcycle. When handling any motorcycle battery, you should wear protective gloves so that you do not suffer acid burns. Eye protection is also recommended because sulphuric acid can cause blindness.

A final check before replacing your battery is that the alternator is operating as it should and properly wired to your battery. Attach your voltmeter leads to the battery terminals, start the motor, and bring the RPMs to 3,000. This should result in a reading of between 13.8V to 14.5V. If the reading is below 13.8V, it may be your motorcycle’s alternator or wiring that is a problem and not your battery.

Adding water to motorcycle battery


Replacing your motorcycle battery

Choose a replacement

The first step is to source a compatible battery for your motorcycle. Compatible batteries may include universal batteries designed to fit a range of motorcycle models or special batteries for your Harley.

Your motorcycle owner’s manual should provide information on the battery required or you can check on motorcycle parts suppliers’ websites. If you’re having problems identifying the right kind of battery, remove the old battery and check its labels.

These days, you may find that you have a wide range of choices. More modern maintenance-free batteries will provide you with more years of problem-free motorcycling. If money is not an issue, you can even consider a lightweight and an efficient lithium-ion battery. Once you’ve obtained the right battery, charge it in preparation for fitting.

Locate the battery

Your owner’s manual should inform you where the battery is located on your motorcycle and how to access it. If you’ve lost the manual, you can probably find a pdf copy of the manual online or simply watch a YouTube video of someone with the same make and model of motorcycle removing their battery.

Commonly, the battery is under the seat and only simple motorcycle tools are required for access. The manufacturers expect you to require access at some point, so they don’t make it difficult for you. However, you will likely need to remove the seat and possibly a protective panel.

Remove the old battery

Begin by disconnecting the negative cable, which is probably black and connected to the negative battery terminal marked “-”. Next, disconnect the positive cable (which may be colored red or be marked by a red sleeve but is not always) from the positive battery terminal marked “+”. As much as possible, tuck the battery cables out of the way to protect them from damage.

The battery may be secured to its mounting by a rubber strap or a metal restraint. Some batteries are similarly protected by foam blocks. Any such protection must be removed before the battery can be taken out.

Straps are usually clipped onto clips attached to the side of the battery compartment and can be popped loose. A metal restraint may be secured by bolts that will need to be unscrewed.

There may be nuts and bolts used to secure the battery cables in place and to secure the battery in place. Be careful when removing these so that they do not fall into your motorcycle’s interior and keep them safe in case they are required when fitting the new battery.

Once all the protection has been removed, the old battery can be lifted out. Discard it carefully, being aware that the acid it may contain will burn skin and recycling is the responsible option for disposal.

Install the new battery

Ensure the battery is fully charged before installation. If the battery is the same size and shape as the old battery, you can slip it straight into the gap left behind by the old battery.

However, modern lithium batteries are often significantly smaller than old batteries. They are often supplied with foam spacers to better secure them into the battery compartment and prevent them from moving around over time.

Once the battery is secured in place with the rubber strap or metal restraint, the cables may be reconnected. This time, begin with the positive (possibly red) cable and secure it to the positive battery terminal marked “+”. Once this is bolted into place, attach the negative black cable to the negative battery terminal marked “-”.

Before you replace the seat or any panels, test that the battery is correctly installed by turning on the ignition and ensuring that the motorcycle’s lights are operating correctly. Once you are satisfied that everything is as it should be, you may rebuild your motorcycle.

Here’s a short video that will take you through the motorcycle battery testing and changing processes

How to Change a Motorcycle Battery

You’re good to go

If you’re followed the above steps, your motorcycle now has a healthy battery that will start the motor quickly and power all the electric components.

Don’t be daunted by the task of testing and, if necessary, replacing your motorcycle battery. Like any practical task, you will improve with practice.

Read your owner’s manual carefully, watch instructional videos, and take it step by step. It is a relatively easy task that will save you from the risk of becoming stranded without transport on a cold winter’s evening.

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Robert Baker

Robert is a content writer and editor at Outside Pursuits where he shares his love for the great outdoors. He also writes in-depth travel blogs for other websites around the world. Robert is passionate about the environment and uses his writing to educate people about the advantages and importance of sustainable living. Robert enjoys creative writing. In 2009, his children’s novel Sally Hemings & the Good Associates won the Children’s Fiction section of the You Write On Book of the Year Award.

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