How To Fix Motorcycle Battery Not Charging? – 5 Fixes!

All motorcycles come with 12 volts AGM battery that powers the lights and electronics of the bike. The battery automatically recharges when you ride the bike because the alternator coupled to the crankshaft generates power.

Last week, I encountered a battery charging problem with my Royal Enfield Classic 350. When I checked the voltage across the terminals, it was only 9.6 volts, while a minimum of 12 volts is required for starting the motorcycle.

So, why is my motorcycle battery won’t charge while riding? A motorcycle battery won’t charge because the regulator-rectifier (RR unit) is faulty, terminals are corroded, there is a loose connection, the battery is dead, or the alternator is not working.

How To Tell If Motorcycle Battery Isn’t Charging?

Many motorcycle manufacturers provide a battery indicator on the instrument cluster. You’ll see a higher voltage (more than 12 V) if your motorcycle engine is started and the battery is charging.

However, some motorcycles don’t have a battery indicator so that you can check the voltage difference across both terminals with the help of a multimeter.

Also, all modern motorcycles come with ECU and OBD port that stores all data and optimizes the air-fuel ratio for better fuel economy.

If your motorcycle has an OBD port, you can check the live data (including battery voltage) with the help of an OBD2 scanner.

How To Fix Motorcycle Battery Not Charging?

There could be any reason why your motorcycle battery won’t charge while riding. Let’s investigate a few common reasons and see how to fix them.

1. Battery Terminals Have Loose Connection

If your mechanic forgot to tighten the battery connections, it could be the reason why your motorcycle battery is not charging. A loose connection on the battery terminals and body grounding creates an electric spark that drastically discharges the battery.

Solution:

Open your motorcycle seat to locate the battery and inspect the wire connection. If the nuts are loose, tighten them with a screwdriver or spanner.

Also, follow the black wire (negative terminal) and find where it’s grounded on the metal body.

It’s generally connected to the non-painted parts of the metal. Tighten the connections with a spanner or screwdriver.

2. Terminals Are Corroded

A battery absorbs moisture from the air and reacts with acid-filled in the battery. This reaction oxidizes the battery terminals, which prevents the current flow. If any of the terminals are corroded, your motorcycle battery won’t charge.

Solution:

Remove your motorcycle seat by unscrewing the necessary bolts and locating the battery. Now, disconnect the negative terminal connection followed by the positive.

Remove the battery from your motorcycle and clean the corrosion around the terminals.

You can use sandpaper and cotton cloth clean the corrosion. Once your terminals are cleaned, connect the positive wire followed by the negative, kickstart the motorcycle and check whether the battery is charging.

If your motorcycle battery isn’t charging, move on to the next solution.

3. Regulator-Rectifier Is Faulty

Your motorcycle has an alternator that generates electricity from the engine’s rotation. But, the current generated by the alternator is AC (alternating current) with fluctuating voltage.

A regulator-rectifier unit in the motorcycle converts the AC current to DC and regulates the voltage fluctuations.

For any reason, if your regulator-rectifier (RR unit) is faulty, your motorcycle battery will not charge.

Solutions:

If your Regulator-Rectifier (RR) unit is faulty, replacement is the only option. You can buy the regulator-rectifier for your motorcycle model and replace it.

If you’re not a DIYer, it’s better to jumpstart your motorcycle with another battery and visit a mechanic shop to get it replaced.

4. Battery Is Dead

The average life of a motorcycle’s battery is anywhere from two to five years. However, due to improper maintenance, your battery could die early.

If you leave the battery discharged for longer periods, there will be a buildup of lead sulfate crystals inside the battery. This phenomenon is known as battery sulfation.

A sulfated battery not only prevents from taking charge but also doesn’t hold a charge.

Solution:

If there is minor sulfation, then go to a mechanic garage, and he will pass a high amperage current to de-sulfate the lead sulfate crystal buildup. If your battery is too old, then you may need to go for a replacement.

5. Alternator Is Not Working

An alternator converts the mechanical energy of your motorcycle engine into electrical energy in form of AC (alternating current).

A faulty alternator could be another reason your motorcycle battery isn’t charging. It happens if the alternator coils burn due to heat or a short circuit.

Solution:

If your motorcycle alternator is faulty, you must visit the nearest mechanic garage. The mechanic will inspect the alternator and repair it if minor faults like wire shorting or fuse burn; you may need to replace your entire alternator.

Conclusion

The most common reasons motorcycle batteries won’t charge are corrosion on the battery terminal and faulty regulator-rectifier (RR) circuit. First, clean the rusting from battery terminals and then inspect the RR circuit. If your RR unit is faulty, you need to replace it immediately.