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Motorcycle Battery Maintenance

Written by  November 30, 2008

Most motorcycles in service today require a battery for the electrical system. If not properly maintained you may have bad charging effects and hard starts. There are two types of batteries that are in use today—conventional lead acid and maintenance free.

Conventional Batteries are of a lead acid type and uses a different type of electrolyte acid, which requires periodic maintenance. In this type of battery, there are four areas to address.

Maintain Water Level. If your battery has removable vent caps, you should regularly check the water level and add distilled water when it is low.
Keep Terminals Clean. Visually inspect the terminals and cables at least once a year for signs of corrosion—especially in hot temperatures. If dirty or corroded, remove the connections with a scraper and wire brush. This ensures a good connection and proper starting.
Keep Case Clean. Keep the top of the battery clean of heavy dirt and oil with a cloth dampened in ammonia or a 50/50 solution of baking soda and water. Rinse with clear water and allow to thoroughly dry.
Keep Battery Charged. If your bike is not ridden weekly, it may be necessary to charge your battery before use. Lack of use is hard on a battery, especially a motorcycle battery which is designed to be charged regularly by an alternator. Any unused battery, regardless of its chemistry, will self-discharge over time, and if allowed to remain discharged, will undergo severe positive grid corrosion and battery failure. The rate of discharge depends on the type of battery and the storage temperature.


The cost of a conventional battery is far less than a maintenance free battery. Another thing that is sometimes overlooked is the battery vent tube. It must be routed correctly without any obstructions or kinking. Also remember to run this vent to the underside of the motorcycle because you do not want battery acid dripping on the frame or electrical wiring.

Maintenance Free Batteries are the most commonly used today. They do cost more and require little or no service to the cell plates. These batteries use a different type of electrolyte and once the initial service has been performed and the ventilated caps are installed, they do not require servicing. Unfortunately, when these batteries show signs of any problems they must be replaced. So as you can see, there are advantages and disadvantages of having a conventional battery versus a Maintenance Free type.

There are two benefits to servicing a conventional lead acid battery.

You can extend the life of your battery when water evaporation has occurred and delay the purchase of a new one. If a sealed no-maintenance battery has water evaporation or if it is affected by a charging system problem, nothing can be done to extend the life of the battery and it must be replaced.
Perform a specific gravity test on each cell with a hydrometer, which may reveal important information about the state of the battery, including if one or more of the cells is defective. This test cannot not be performed on a sealed battery.

As riders, we can inspect the battery terminal posts, the case and general condition of the battery. I want to add that having the positive and negative terminals cleaned and a light coat of white lithium grease will help keep the battery terminals from corroding. This is a great tip and will also aid in removing the bolts that secure the cables to the battery post. If you must add water to a conventional battery, use only distilled water because the minerals have been removed and will help to not sulfate the battery faster than normal. You can add water using an old water bottle or reuse the bottle that comes in the box with your replacement battery. Simply add a piece of vent tubing and fill the battery to the top fill line. Keep in mind that sulfuric acid is an enemy to clothes, skin and eyes so use protective eyewear, rubber gloves and work clothes and remove all jewelry. Please use common sense and safety when refilling a battery. And as a general rule of thumb, always remove the negative cable first when removing the battery. This prevents the cables from touching the frame and any other electrical components, which can create an arcing that will either short the main fuse or ruin those expensive charging or ignition components.

To clean the terminal posts, I suggest that you use either a nylon bristle brush or soft brass bristle brush. You only want to keep the corrosion off the cable ends and not damage the battery post. This can be done with Maintenance Free batteries as well.

So in closing, the best way to maintain a battery is to create a schedule of when to check the water level, dirty terminal ends and all around condition of the case of the battery. Checking these items will maximize the life of your battery and will also give you a visual inspection that you as a rider can perform in a matter of minutes.
Again, I want to really stress eye protection when filling or refilling a battery, because you only have two eyes, so wear eye protection. You will be glad you did.

On our tough-o-meter scale of difficulty, I rate this is a 1, and all of us should be able to handle this.

B-safe out there!

Dave Miller