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13 Reasons Why a Generator Won’t Charge A Battery

13 Reasons Why a Generator Won’t Charge A Battery

In an emergency, your generator may be one of the last resources you have to power your home or business before the power goes out completely. Although your generator can provide an abundance of energy, sometimes it just won’t work correctly, and you’ll find yourself without electricity when you need it most.

Some of the most common reasons why a generator won’t charge a battery include a faulty or dead battery, loose wiring, corroded connections, an excessive electric load, a disconnected battery, a faulty charger, a faulty voltage regulator, a blown fuse, and oxidation of a battery terminal.

Sometimes, a generator simply doesn’t seem to be able to properly charge the battery, even if every component is seemingly functional. There’s a wide range of causes that might be responsible for this issue, and if you want to solve the problem, it’s essential to determine which one you’re dealing with so that you can find the right solution.

1. Faulty or Dead Battery

If your generator doesn’t charge the battery, it could be because the battery is faulty or dead. If the battery is dead, you’ll need to replace it. If the battery is defective, you may be able to have it repaired. Either way, you’ll need to take your generator to a qualified technician to get it checked out.

How To Fix

To check if the battery is the problem, attach a voltmeter to the battery terminals and see if there is a voltage reading. If not, the battery is probably dead and will need to be replaced. If there is a voltage reading, the problem may be with the generator itself. Try troubleshooting the generator to see if you can identify the problem.

2. Your Battery Is Draining Too Fast

One of the main reasons your generator won’t charge the battery is that your battery is draining too fast. When this happens, the generator cannot produce enough power to keep the battery charged. This can be caused by several factors, including a bad connection between the battery and the generator, a problem with the charging system, or a faulty battery.

How To Fix

Make sure to read instructions on how to handle your generator battery before tinkering with it. Try turning off any unnecessary electronics and see if that makes a difference. If not, you’ll have to get your generator checked by a professional to see if it’s working correctly, as the issue might be well beyond your scope of expertise. 

3. Loose Wiring or Corroded Connections

The wires that connect the battery to the generator can become loose over time, or they may be corroded from exposure to the elements. If the connection isn’t secure, then the generator won’t be able to properly charge the battery. Additionally, if the wires are loose or the connections are corroded, electricity may not be able to flow properly, and the battery will not be charged.

How To Fix

Check the wiring between the generator and the battery to ensure it’s tight and secure. Additionally, check the connections for corrosion and clean them if necessary. If these approaches don’t fix the problem, you may need a new battery or a new generator. If you have a corroded connection, you’ll need to clean it with a wire brush or sandpaper to remove the corrosion.

4. The Load Is Too High

If the load on the generator is too high, it may cause the equipment to shut down. This could happen because the engine is overloaded or the generator is low on oil. If this is the case, the battery will not be able to charge. 

The generator needs to have a certain amount of power available to generate the required electricity to charge the battery. If the load is too high, the generator won’t be able to produce enough power, and the battery won’t get charged (source).

How To Fix

To fix this, try turning off some of the appliances or devices you are running off of the generator and see if that makes a difference. If not, you may need to get a bigger generator. You can also try charging the battery at a lower voltage. If nothing seems to work, as always, don’t hesitate to contact a professional.

5. Disconnected Battery/Battery Charger Switch

Oftentimes a simple mistake can be the root cause of a seemingly impossible to fix issue. Simply forgetting to connect your battery or turning on the battery charger switch might be why your generator isn’t operating as it’s supposed to. Always make sure to check both of these components before assuming something wrong with the generator. 

How To Fix

Check to see if the positive and negative terminals are both connected. If they are, the next possibility is that the battery charger is switched off. Check the switch to ensure it is in the “on” position. If your generator has an automatic voltage regulator (AVR), make sure it’s turned on.

6. Tripped Battery Charger MCB

A Battery Charger MCB is a safety device used to prevent the battery from overcharging. If the battery charger senses that the battery is getting too hot, it will trip the MCB and stop the charging process. This prevents the battery from becoming damaged or overheated and keeps the generator running safely. A battery charger MCB can trip for many reasons, including:

  • A power surge from the generator results in excess current
  • A problem with the generator’s alternator
  • A problem with the generator’s battery

How To Fix

If your generator won’t charge your battery, the first thing you should do is check the breaker on your battery charger. This breaker is usually a small, square box with a red handle. If the breaker is tripped, it will be in the “off” position. To reset the breaker, simply switch it to the “on” position and wait for it to snap back into place. If the breaker is not tripped, there may be a problem with your battery charger.

7. Faulty Battery Charger

If your generator battery charger is faulty, it could be why your generator won’t charge the battery. The battery charger is responsible for converting AC power into DC power to charge the batteries. If it’s not working properly, it won’t be able to carry out its intended purpose.

You should check the charger and ensure that it’s working correctly before using the generator. Another possibility is that the charger is not getting power from the outlet. If the outlet is not working, you will need to check the circuit breaker.

How To Fix

First, check to see if the battery charger is plugged in. If it is, check the circuit breaker to ensure it’s not tripped. If the circuit breaker is okay, check the fuses to see if they’re blown. If they are, then replace them. If none of these approaches fix the problem, you may need to replace the battery charger altogether.

It is also possible that something is wrong with the charging circuit inside the battery charger. This is much less common than the other two issues, but it is still possible. If you suspect this might be the case, you should take your charger to a qualified technician for further testing.

8. Converter Breaker Is Off

The converter is the component that changes the power from AC to DC so that it can be stored in the batteries. Without the converter, the generator can’t do its job. Check to see if the breaker is flipped “off,” and if so, flip it back to the “on” position. If the breaker trips again, you may have a short in the wiring or a defective converter.

How To Fix

The converter breaker is located in the main electrical panel, and it supplies power to the converter. Make sure the breaker is in the ON position before starting the generator. If the problem persists, there may be an issue with the converter itself. You’ll need to call a professional for assistance.

9. Generator Has Been in Storage for Too Long

One of the most common reasons a generator’s battery won’t hold a charge is that the battery itself is old. Batteries have a limited lifespan, and after a certain number of years, they simply stop working. If your generator is more than a few years old, the battery is likely too old to hold a charge.

Another reason why your generator’s battery may no longer be holding a charge is because of sulfation. This process occurs when batteries are left unused for long periods. Sulfation essentially “clogs” up the battery cells, preventing them from holding a charge. 

How To Fix

If you’ve had your generator in storage for a while, the battery may have gone bad. If the generator is more than a few years old, it’s probably time to replace the battery. If you’re not sure how long your generator has been in storage, it’s best to err on caution and take it to a professional for servicing.

10. Faulty Voltage Regulator

A voltage regulator is one of the most critical components of a generator. It ensures that the voltage output by the generator is stable and within the correct range. If the voltage regulator is faulty, it can cause the generator to output too much or too little voltage, damaging the battery.

How To Fix

You can test the voltage regulator with a multimeter to see if it’s working correctly. If it is faulty, you’ll need to replace it. You can check the voltage regulator by consulting your generator’s manual or contacting a certified technician. When you’re not sure, it’s always best to err on the side of safety and enlist professional help.

11. Tripped Breakers or Blown Fuses

One of the most common reasons why a generator won’t charge the battery is because the circuit breaker or fuse has been tripped or blown. If this is the case, simply reset the breaker or replace the fuse and try again. If the problem persists, there may be an issue with the generator itself.

How To Fix

You’ll first need to identify which breaker or fuse has been tripped or blown. Once you’ve done that, replace any blown fuses. Replacing the blown fuses should be a straightforward process that doesn’t require much previous knowledge or experience. However, if the problem persists, contact a qualified electrician.

12. Oxidation of Battery Terminals

Another common reason why a generator won’t charge the battery is oxidation on the battery terminals. Over time, the terminals can become coated with a film of oxidized material that prevents electrical current from flowing between the terminal and the battery. 

This can be caused by many factors, including exposure to the elements or simply age. In most cases, you can clean the terminals with a simple wire brush to remove the oxidized film and restore connectivity.

How To Fix

This is usually an easy problem to fix, but if you don’t have access to a terminal cleaning brush, you may need to replace the terminals altogether. To clean the terminals, simply remove the battery and clean the terminals with a wire brush or sandpaper. If the corrosion is severe, you may need to replace the terminals.

13. Open Circuit in the Charging Circuit

If your generator doesn’t charge the battery, it could be due to an open circuit in the charging circuit. This can happen if the battery terminals are corroded or the battery cables are damaged. These types of issues can occur due to exposure to the elements or prolonged use. To fix this, you’ll need to clean the terminals and replace the cables.

How To Fix

If you suspect an open circuit, check the wiring and connections first. If they appear to be okay, then check the fuse. If the fuse is blown, replace it with a new one and see if that solves the problem. In case the problem persists, don’t hesitate to enlist the help of a professional.


This article looked at some possible reasons why a generator might not charge a battery. Some of the reasons include a faulty circuit breaker, a faulty battery, or a problem with the wiring. If you’re not sure what the problem is, it’s always best to take your generator to a qualified technician to have it checked out.

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