Motorcycle Battery Won’t Charge: Why and How to Fix It

Is your motorcycle battery not charging? Are you frustrated trying to figure out the reason why it won’t start? Are you even more frustrated that you’re struggling to fix it? If you are finding yourself in this position, this post can help you find some answers.

A motorcycle battery isn’t charging because it is dead. This can be fixed by removing the battery and cleaning the posts, checking the open-circuit and cell voltage, refilling the cells with Epsom salts, fully charging the battery, and performing a motorcycle battery load test.

To learn more about why your motorcycle battery isn’t charging and how to fix that, keep reading.

Why The Battery Is Dead

The main reason most people’s motorcycle batteries are dead is that the charger has been overworked, leaving the battery without any charge.

This issue can be resolved fairly easily with a few steps:

  1. Remove the battery and clean the posts.
  2. Check the open-circuit and cell voltage.
  3. Refill the cells with Epsom salts.
  4. Fully charge the battery.
  5. Perform a motorcycle battery load test.

Once these steps have been completed in order and in their entirety, the battery should restart without any issue. If the battery does not respond or revive at all, that is an indicator to purchase a new battery.

Remove The Battery And Clean The Posts

The first step to fixing a dead battery is to remove it from the motorcycle so various parts of the battery are more accessible to work on. It is important that you make sure that the battery is fully cooled before removing it from the motorcycle. Once you have the battery removed, you can then take a screwdriver and remove the negative cable followed by removing the positive cable.

If after removing the cables you see any corrosion, you can clean that off by making a paste with baking soda and distilled water and carefully scrub it off with steel wool or a toothbrush. Be patient, corrosion can take some time to work off.

Check The Open-Circuit and Cell Voltage

Now that you have the posts removed and cleaned, you can get a more accurate read of the battery’s open-circuit voltage. When using a voltmeter, make sure it is equipped with a Multimeter in DC voltage mode. The red probe should be connected to the positive post, with the black probe connected to the negative post. Once those are properly connected, your voltmeter should give you a reading on the voltage of the battery.

A healthy battery is typically 12.6v or higher, if the reading is 7.5v or lower that is a sure sign that your battery needs to be replaced altogether. If your battery is between 0 to 7.5v, your battery is majorly damaged and it would be worthless trying to revive it.

To check the cell voltage, do not use the voltmeter. You will need to use a multimeter. To do this, you will have to expose the cells by removing the plastic cover that is attached to the top of the battery. After that is done, attach the negative probe to the negative terminal and dip the end of the red probe into each cell’s electrolyte. This will give you a reading on the DC voltage mode. If it is under 1.50v, it means the cells are weak but revivable. If it is under 1v or 0v, there is no purpose in reviving them.

Refill The Cells With Epsom Salts

Now that you are sure that you can revive the battery, carefully empty the cells into a bucket, along with the sulphuric acid. Take care and wear protective gloves and goggles. When all the acid is out of the battery, add baking soda to the bucket. This will neutralize the acid. After doing that, boil a quart of distilled water with 8oz of Epsom salt until the salt is dissolved. Turn off the heat and let the water cool completely and then take a syringe or funnel and pour the mixture into each cell until they are full.

Do not put the caps back on yet. You will need them off for the next step.

Fully Charge The Battery

Take the battery and place it on the charger. At the very least, the battery will need to remain on the charger for 18 hours, and at the very most 24 hours.

The charging capacity will vary depending on what charger you use, but it is always a good assumption to leave the caps off when charging. This is important because if you were to put the caps on before charging, pressure could develop underneath the caps and create safety issues, such as the battery overheating causing the liquid to spill out.

After the charging period is completed, you will need to retest the open circuit. This will tell you whether or not the battery is fully charged or not, indicating if you need to let the battery charge more if you have not already reached the maximum time limit. If the battery is fully charged, it should be between 12.6v and 12.7v.

Perform A Motorcycle Battery Load Test

The final and most important step is the battery load test. To perform this test, you will need a battery load tester which will give you the diagnosis of whether or not your steps and efforts to improve your dead battery were successful or not.

Once you have those results, it is time to place the battery back in your motorcycle. Make sure it is connected correctly, with the positive jumper connected to the positive port and the negative jumper connected to the negative port. When the battery is properly placed back in the motorcycle, you will need to test the voltage one more time with your multimeter. If the bike starts with no issues and reads as 9.5v or higher, your bike has successfully been recharged.

If your battery falls under the 9.5v, you can take it out again and run through the process one more time, but unfortunately, if your battery falls under 6v, there is no use trying to revive it again and you will need to replace the battery entirely.