Motorcycle Battery Is Draining: 9 Causes And Fixes (Explained)

Have you planned a trip? You tried to start your motorcycle, but it wouldn’t turn over. You are startled to realize that the battery in your bike has run down, which is the primary reason why it would not start. 

Because I ride and have run into this problem more than once, I was able to figure out nine things that contribute to it.

If you are also having this problem and want to find a solution to it, then you should read this post very carefully because I will explain all nine of the possible causes.

Why Is My Motorcycle Battery Draining?

If the battery on your motorcycle is draining quickly, there could be a number of reasons why this is happening. The most common reasons are a weak battery, different devices that are connected to the battery, a short circuit, a switch that has been left on, corroded connections, a broken alternator, stator, or regulator, and heat.

A list of the reasons why a motorcycle battery drains quickly is provided below:

1. Weak Battery

If your motorcycle battery is draining, one of the first things you should check is whether or not the battery is weak. A weak battery will not be able to hold a charge as well as a strong battery, and this can cause it to drain more quickly.

There are a few ways to test whether or not your battery is weak. One way is to use a voltmeter to measure the voltage of the battery when it is fully charged. If the voltage is below 12 volts, then the battery is considered weak.

Another way to test the strength of your motorcycle battery is to try starting your motorcycle with just the battery. If the engine struggles to turn over or if the headlights are dim, then this is an indication that the battery is weak.

If your battery is indeed weak, then you will need to replace it with a new one. However, if your battery is still strong, then you can move on to checking for other causes of why your motorcycle battery might be draining.

2. Multiple electrical devices attached

If you’ve got multiple electrical devices attached to your motorcycle (like a phone charger, heated grips, etc.), that can also lead to your battery draining faster than normal.

To resolve this, unplug some of the devices or, if that isn’t possible, upgrade to a larger capacity battery. You should also make sure that the devices are properly installed and wired; if they’re not, that can also cause problems.

3. Short Circuit

The next possible cause is a short circuit. This is when there is a break or crossing in the circuit. This can happen when the battery is damaged or if there are loose or corroded wires.

When there is a short circuit, the current will bypass the load and go straight to the ground. This will cause the battery to drain very quickly.

To fix this, you will need to find the break in the circuit and repair it. You may also need to replace the damaged wires.

4. Motorcycle Key Left ON

The fourth most common reason your motorcycle battery might be draining is because you left the key on. Even if your motorcycle isn’t running, leaving the key in the “on” position will allow electricity to flow and slowly wear down the battery.

To avoid this, make sure to turn the key all the way off when you’re done riding for the day. And if you’re going to be storing your bike for a long period of time, it’s a good idea to remove the battery altogether.

5. Bad voltage regulator or rectifier

If your motorcycle battery is draining, one of the causes could be a bad voltage regulator or rectifier. The voltage regulator is what regulates the amount of voltage going to the battery, and the rectifier is what converts alternating current to direct current.

If either of these components is not working properly, it can cause your battery to drain. To test if this is the problem, you can use a voltmeter to measure the voltage coming from the regulator or rectifier. If the reading is below 12 volts, then this is likely the problem.

6. Corroded connections

If you find that your motorcycle battery is draining, one of the causes could be corroded connections. When the terminals or other connections are corroded, it can cause a loss of electrical current, which then causes your battery to drain.

To fix this, you’ll need to clean the connections with a wire brush. First, disconnect the negative terminal, then the positive terminal. Clean the terminals with the wire brush until they’re shiny and free of corrosion. Once they’re clean, you can reconnect them and see if that solves the problem.

7. Damaged alternator or stator 

The alternator, or stator, is responsible for generating the electricity that gets stored in the battery. If these components are damaged, they might not be able to generate enough electricity, which will cause the battery to drain.

You’ll know if your alternator or stator is damaged if you notice that your headlight is dimming or flickering. Another telltale sign is if your engine is making strange noises. If you suspect that your alternator or stator is damaged, take it to a mechanic for a diagnosis.

8. Bad ground connection

The ground cable is what completes the circuit. If there’s a problem with the ground cable, it can cause all sorts of issues, including a battery that drains too quickly.

A bad ground connection can be caused by a number of things, including:

  • A loose ground cable
  • A corroded ground cable
  • A ground cable that’s not properly connected to the battery or frame

If you suspect that your ground connection is the issue, the best way to fix it is to take your bike to a qualified mechanic and have them take a look.

9. Vibration and heat

You might not know this, but vibration and heat are two of the biggest enemies of your motorcycle battery. Heat speeds up the chemical reactions inside the battery, which causes it to self-discharge. And vibration can damage the internal structure of the battery, causing it to lose capacity.

So what can you do to protect your battery from these two evils? First, make sure to keep your motorcycle in a cool, dry place when it’s not in use. And second, invest in a good-quality battery case or cover. This will help insulate your battery from vibrations and protect it from the elements.

How Do You Find What Is Draining The Motorcycle Battery?

If you want to find out what is draining your motorcycle battery, the best thing to do is to take it to a mechanic and have them test it. They’ll be able to hook up a special device that will tell them exactly what is going on and what needs to be fixed.

If you’re feeling a bit handy, you can also try testing the battery yourself. You’ll need a multimeter for this, and you can find out how to use one by reading the owner’s manual for your motorcycle. Once you have the multimeter, all you need to do is test the voltage of the battery while it’s running and while it’s not running. If there’s a big difference, then you know that something is draining the battery.

How Do I Stop My Bike Battery From Draining?

The first step is to check your charging system. You can do this by starting the bike and revving the engine a few times. If the charging system is working properly, the voltage should rise to between 13.5 and 14.5 volts. If it doesn’t, there’s a problem with your charging system and you’ll need to get it fixed.

Another thing you can do is to make sure that all the lights on your motorcycle are off when you’re not using them. Headlights, turn signals, and brake lights can all drain your battery if they’re left on for too long.

If you’re still having problems with your battery draining, you may need to replace it with a new one.

Do Motorcycle Batteries Discharge When Not In Use?

You might be wondering, “Do motorcycle batteries discharge when not in use?” and the answer is… unfortunately, yes.

The main reason why motorcycle batteries discharge when not in use is due to something called the self-discharge rate. This is when a battery slowly loses its charge even when it’s not being used.

The good news is that there are ways to prevent this from happening. For example, you can invest in a battery tender or disconnect the battery entirely when you’re not riding. You can also try some of the other fixes on this list, like making sure your bike is parked in a cool, dry place.

How Long Can A Motorcycle Sit Without Starting?

This one is a little tricky because there are a lot of variables at play. If you have a brand new bike, you can probably get away with letting it sit for a few weeks without starting it. However, if your bike is older, you might want to start it every week or so just to keep everything in working order.

One thing to keep in mind is that if you live in an area with extreme weather conditions (i.e. it’s freezing in the winter or blazing hot in the summer), you’ll want to start your motorcycle more often to prevent any damage from the elements.

How Do I Keep My Motorcycle Battery Healthy?

The good news is that there are a few things you can do to help prolong the life of your motorcycle battery and keep it healthy.

First, make sure you’re regularly cleaning the battery terminals and connections with a wire brush. This will help to remove any dirt or corrosion that might be causing issues.

Another thing you can do is to use a battery tender or charger whenever you’re not using your motorcycle for an extended period of time. This will help to keep the battery charged and prevent it from draining.

Finally, be sure to check the level of electrolyte in the battery regularly. If it’s low, add distilled water to bring it back up to the proper level.

Doing these things will help to ensure that your motorcycle battery stays healthy and lasts for as long as possible.

Should I turn on my motorcycle every day?

If you don’t ride your motorcycle every day, you might be wondering if it’s okay to just let it sit. Well, the short answer is no—if you want your motorcycle battery to last, you should turn it on and let it run for at least 15 minutes every day.

Here’s why: When you let a motorcycle sit for too long, the battery will start to drain. And once the battery drains, it’s harder to recharge and can shorten its lifespan. So if you want to keep your motorcycle battery in good shape, make sure to turn it on and let it run for a bit every day.


The battery is an important part of the motorcycle, and the way it works is very important. If it drains all of a sudden, then you have a major problem on your hands. There are a variety of factors, some of which I have outlined above, that can cause motorcycle batteries to die.

 You won’t need to take your vehicle to a repair shop if you read this article and put its advice into practice.