How to Fix a Motorcycle Battery That’s Not Charging

Here’s the scenario: You hop on to your bike which was cleaned just a few hours ago. You push your trusty old start button expecting a shrill grind from your starter and followed by a loud grunt from your crankcase. Then suddenly, the only thing that you hear is a small gurgling sound that quickly dies off. Or even worse, not even a sound. Dead silence. It just won’t start.

Instinct would tell you, the battery might be dead. A few things may cross your mind as to what could be the problem. First, you should rule out any other problem other than your battery. Here’s how to check:

  1. Headlight still comes on bright, and horn sounds normal- not a battery problem
  2. Headlight not working, the horn is weak or not functioning- a battery problem
  3. Starter not working, no sound or weak attempt- a battery problem
  4. Physically inspect your battery and check for any for the following:
  • A bulge in the case
  • Leaking
  • Crack in the plastic
  • Broken terminal
  • Discoloration of battery fluid.

If any of these physical symptoms are present, immediately replace the battery. Any deformity or leak is a danger of toxic fluids or fumes and it even presents a fire hazard.

Once you get to confirm 2 and 3 as stated above are the symptoms, then you can proceed to check your battery. Your battery could either be new or old, whatever it might be, it definitely has one problem. It’s not holding a charge.

Now that we have ascertained that it is a battery problem we further try to isolate the issue by checking any one of these possible problems:

  1. Low Battery
  2. Charging System Problem
  3. Bad Battery

How to Diagnose Your Motorcycle Battery

1. Low Battery

Before starting your engine, first, test your battery directly. Set your voltmeter at 20 volts DC scale, then connect your voltmeter across your battery terminals. Connect the red tip of the voltmeter with the positive, and the black tip to the negative terminal.

Your battery reading must be 12.7 volts at full charge. Anything lower than that could mean the battery needs additional charging, or it may have some other problem.

If you don’t have a voltmeter yet, consider investing in one because it’s a very useful device and pretty affordable as well.

Fix: Charge your battery


  1. For lead-acid batteries, check electrolyte level and top up with pure distilled water prior to charging. Do this until the plates are submerged. Do not use tap water as it may damage your battery.
  2. Charge battery inside of 12-24 hours or until fully charged
  3. Top off again with distilled water to the highest level.
  4. Then charge for another hour for the acid and water to mix.
  5. Make sure to put back removable caps then reattach to the battery to the engine.

Assuming that you may have already charged your battery and it came up fully charged, then you can now proceed to check the voltage with the engine running.

2. Charging System Problem

Use a voltmeter to check the voltage of your charging system. This will show how much electricity is being passed around while your bike is in normal operation. Assuming that the engine is running, set your voltmeter at 20 volts DC scale.

Connect the red tip to the positive point of the battery, and the black tip to the negative point. If the voltage reaches, 13.5-14.5 volt range, you can rule out a charging system problem.

Conversely, anything lower than 13.5 indicates a charging system problem. The battery itself will not fully charge. which then would lead to impaired electrical performance.


Unless you have experience as a mechanical electrician, it is recommended that you take your bike to an expert electrician for further diagnosis and pinpoint repair as to the source of the problem. If you are looking to DIY, always refer to your manual for specs.

3. Bad Battery / Not charging

So here comes the clinch, if after all the practical tests that may have been done, and we have established that it is the battery is dead, here are some of the things that you can do to remedy this problem.

Fix: For Lead-acid battery

If not by anything else, the problem may be caused by sulfation. This happens when the battery is deeply discharged or totally drained. It causes sulfur from the acid in the battery to build up on the lead plates inside the battery. It then causes it to impede the flow of electric current. This may also corrode the plates, however, if the corrosion is not that severe you can still save the battery


  1. Safety first. Work in a well-ventilated area. Wear protective clothing and keep your battery away from open flames.
  2. Unscrew cell caps. Completely drain the battery fluid (be careful not to come in physical contact with the acid).
  3. Mix 8 ounces of Epsom Salts and a quart of distilled water. Do not use tap water, it may damage your battery. Use a plastic funnel to pour your battery solution in each cell. Once all the cells are filled, distribute the solution by shaking the battery gently.
  4. Charge your battery using a trickle charger or a slow charger whenever available. Avoid using regular charge rate as you would with cars, as it may damage your smaller motorcycle battery. Charge the battery with the cells open, leaving the cell caps off.
  5. Charge overnight or when the indicator says fully charged. Cover the cells with the cell caps, then reinstall the battery. Test run battery and check the voltage when warmed up. The voltage should be within the range of 13.5-14.5 volts.

Although there is another variation of this Epsom salt method, the process is pretty much very similar. We can conclude that the Epsom method might possibly be the only effective way of reviving dead batteries to date.

If after doing all these steps and you find the procedure successful, it is best to do a load test as well. This is looking to see what your battery’s performance would be under a full load of headlights, blinkers, and horn under normal operating conditions.

How to Take Care of Your Motorcycle Battery

One of the best ways to fix a dead motorcycle battery is to maintain it by making sure all its peripherals are working properly.

Extend the life of your battery:

1. Periodically charge your battery

If you don’t use your motorcycle too often, try to charge your battery every 30 days to minimize sulfation. Every time a battery discharges it loses a part of its life giving it a general expiry period of 1-3 years. Regular use would then keep it charged and well maintained, and even possibly extend 1 or 2 more years.

2. Ensure a Working Voltage Regulator

It is the job of a voltage regulator to maintain and regulate the prescribed voltage that is circulated in the electrical circuit of your motorcycle. Without it, or if it is faulty, raw electricity produced by the battery becomes uneven and sometimes over the prescribed range. This can cause snippets of pulsating overload that may shorten your battery life. Have your regulator checked by a qualified technician for performance and diagnosis.

3. Proper Ground Connection

Your manufacturer more often than not has a preset grounding of your battery to ensure proper operation. The general advice of good grounding of your battery is that the ground wire is to be attached to the case of the engine, not to the engine itself. Again, this is to protect from the battery’s sudden burst of electricity and to prevent short circuits due to overloading.

4. Avoid Overloading Your Battery

It is important to do a load test to check your battery’s capacity. This is against the engine running, with lights on, horn and all other accessories that use electricity. Run your engine and turn on all electrical accessories. Read the voltage with a voltmeter and see if it is running on less than 13.8 volts. If the answer is yes, then your electrical system is overloaded. All of these greatly contribute to a shorter life span of the battery.

  1. Reduce electronic accessories that are not stock to lessen the load and avoid overstraining the circuit.
  2. Use a more powerful alternator to assist in powering all your accessories without having to remove any of it.

5. Leak-Free Circuit

If the electrical circuit of your bike is leaky it causes an irreparable drain on your battery that ultimately shortens its life. Aftermarket mods like alarm, GPS, high beam light, etc, may have leaks that may damage your battery. Have your expert electrician see if any leaks are present and have it corrected.

6. Heat and Vibration

Your battery won’t be able to avoid being affected by these two elements, and there is not much you can do with how your OEM positioned it. In any case, you can minimize the accelerated expiry of your battery by acquiring AGM or Gel Cel batteries instead. These types of batteries can survive heat and vibration better than lead-acid batteries. Although they don’t last as long.

Although batteries do have a fixed shelf life, you can actually extend it by adding effort into taking care of it. And avoid wasting energy by regularly inspecting any visible component of your electrical circuit. As always, it would wise to consult your expert electrician.

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