7 Signs of a Bad Motorcycle Battery

7 Signs of a Bad Motorcycle Battery

Starting to realize that your motorcycle’s battery may be failing is a sad event indeed. However, it is also a time to bring in new changes that will result in a better motorcycling experience altogether.

No matter how many motorcycle battery reviews you go through before purchasing one, most batteries need to be replaced every 3 years or so anyway. If your battery starts failing before that time period, there are a few ways of telling that it is happening.

This article will discuss a number of possible reasons as to why your battery might be failing, and help you determine whether it might be time to get a new one or repair the existing motorcycle battery.

The 7 Signs of a Bad Motorcycle Battery

Here are the signs of a bad motorcycle battery:

  • A Deformed Battery
  • Built-Up Sulfation
  • Motorcycle Not Starting Properly
  • Receding Horn Volume and Dimming Headlights
  • Irregular Readings on the Multimeter
  • Idleness
  • Old Age

Before we begin, one important thing to keep in mind is that your motorcycle may malfunction despite the battery being in perfect condition. There may be other mechanical or electrical problems at play that are causing your motorcycle to underperform.

Another thing to heed is to never allow any conductive object to act as a connection between the red (positive) terminal of the battery and other metal parts of the motorcycle.

Motorcycle Battery

This will cause your battery to fry, and may even electrocute you. If you are uncomfortable testing your battery’s condition yourself, feel free to consult with a professional. With that out of the way, let us take a look at some of the most common signs that you have a bad motorcycle battery.

A Deformed Battery

Before taking out a multimeter, simply take a look at your motorcycle battery and check for discoloration, any leakage, bulges, broken terminals, bumps or cracks. Often, whether your battery has gone bad or not can be determined through a simple physical check.

Built-Up Sulfation

One of the most common causes of battery failure is the sulfur molecules of the lead-acid becoming greatly discharged and sticking to the lead plates of the battery. This eventually causes the battery to die.

Motorcycle Not Starting Properly

At one point in your vehicle’s life, you will notice that it takes a few tries before your motorcycle starts up.

There is no need to try to jumpstart motorcycle then as this will be a prime indicator of a bad battery that needs to be replaced, otherwise you may find that your motorcycle stops in the middle of a ride, leaving you stranded.

Motorcycle Battery

Receding Horn Volume and Dimming Headlights

It may not seem like it, but your motorcycle battery affects almost all parts of your vehicle. If you notice your horn sounding less loud or your headlights seeming dimmer or not covering as much range as before, then those are all indicators of a failing battery that needs replacement.

Irregular Readings on the Multimeter

A multimeter is a very useful device to own, especially for motorcyclists. They make it much easier to test and detect flaws in motorcycle batteries.

If you are using a multimeter to test your battery and the readings seem uncertain or abnormal (such as a voltage of less than 12V), then that is a sure sign of a bad motorcycle battery.


It is a known fact that a motorcycle battery that is in use regularly is also less likely to go bad. This is why a lot of batteries fail during long winters when the motorcycle is not being ridden.

After long periods of sitting idle in the garage, your motorcycle will have difficulty starting up, or it may not start up at all. These are both indicators of a failed battery that needs replacement.

Old Age

This is an obvious one, but if you feel like you cannot remember when you bought your current battery, then you will also notice certain signs indicating that your battery needs to be replaced. You will likely face difficulties starting up your motorcycle, having your battery run as long on a full charge as it used to.

If so, you should replace your motorcycle battery immediately as an aged battery can lead to other mechanical flaws in your vehicle. Even if your battery runs moderately well, you should still replace it after four years, regardless.


Like it or not, a simple and compact battery can do a lot of harm to your motorcycle if not taken care of properly. It is important to act fast if you notice anything amiss in terms of your vehicle’s performance.

You can also invest in extra equipment such as a motorcycle battery tender and the right kind of charger to make sure your battery lives a long life. However, that still means that you should replace your motorcycle battery every four years so that your motorcycle itself does not end up becoming faulty.

joshua mattie

Joshua D. Mattie

My motorbike addiction began with 50cc at 5 years old. I rode motocross as a teenager & into my 20's when I worked as a mechanic. This helped me to see the light—sportbikes & cruisers became a passion. Now I'm building BikersRights to be the #1 resource for everything on 2 wheels!

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