Battery charger flashing red light

Battery Charger Flashing Red Light: Is it Okay?

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A man who is into tech will indeed have to go through the pain of charging all the batteries of their precious devices before the night of their usage. And some chargers work at certain functionalities and are very different based on the devices. So, it is quite normal for any individual, even the most tech-savvy person, to get confused by the processes.

My buddy once failed to use his capture simply because he couldn’t charge the batteries of the camera. He assumed since the charger was blinking red lights, his batteries were getting charged. Still, unfortunately, he couldn’t be any more wrong because when the battery flashes red light, it usually means there’s an issue in the charging or the device. 

You are probably in the same dilemma, and for that reason, I am here to help you out. So, without further ado, let us proceed. 

Before we dive: What do the lights mean on chargers?

The lights will tell you the activity that is going on with your charger. One light will tell you that your batteries are getting charged, and the other will tell you that it not getting charged. And, also there are specific effects on your lights that will show some form of errors with either your battery or the charger and also, in some cases, cable issues.

If your question as a whole is why it is necessary to have any light in the first place, then you need to know that without light, you cannot understand if you have power on your charger or not. 

Green Light: This means the battery is charging.

Red Light: If it shows red light, then it is fully charged.

Red Light and Green Light: If it shows both lights together, then there might be a polarity disparity in the battery, or the battery might have voltage fluctuations. 

Slowly blinking Red Light: If you have connected the wrong battery or a faulty battery, then the charger will slowly flash red light.

Fastly blinking Red Light: If the charger is blinking fast, then it is probably your charger that is faulty. 

These effects will indeed differ from device to device. So, be sure to know exactly what light effect shows which settings, but in general, what I have told you goes along with most devices.

In some devices, Greenlight might mean your battery has become fully charged, and in red light, it means the battery is charging. 

Which battery devices are we talking about? 

Which battery devices are we talking about

You could be aroused by the many devices that contain red lights and green lights as a way to understand what is going on in your charger.

So, I would like to mention the names of a few devices that would allow you some clarity in relating with your device along with knowing other devices that features the same. 

1. Balance Charger: This charger makes sure that the cells in the battery are not at disparity. This charger has red and green lights to make you understand if there is an issue with the polarity of the batteries. 

2. AA battery charger: AA battery chargers are the most common of them all. If you are a cameraman, then it is by default you own an AA battery charger or higher. The red lights in the charger could indicate high or low voltages.

3. Tool Kit Charger: Your drill machine will evidently require a bit of charging after prolonged usage. It could flash red light due to a bad connection or not placing the 1.5 amp battery properly. 

4. Car Battery: Your car battery could also indicate red light if it is not adequately charged or the connections are unstable. 

Now you could be using a different device that is flashing red, and you are somewhat confused as you cannot find it relatable. Bear with me over this, as I will now go to the details on why your battery charger is flashing red lights. 

Why is my battery charger flashing red lights?

What do the lights mean on chargers

We have known which devices have these lights along with which type of lights are there in general. Now, let us go through why red lights start to flash in your charger. 


You need to keep your battery at optimum room temperature to keep your batteries charging. Temperature can be a massive issue for your batteries not to charge. You could be utterly clueless about it, but it most definitely can be the main. Charging generates electricity which generates heat.

If the temperature is too hot, then the charger will become even heated, which may lead to the chance of an explosion. Evidently, which is exactly why your charger flashes red lights. Also, there can be a few instances when your charger isn’t correct because the room temperature is below standard. 


Sometimes you must realize that the product has reached its peak. You probably have been using it for too long, and it is dying out. Your charger is probably flashing red lights because it has gone old.

The internal components inside have started to rust, leading to a loss of connections, showing red lights flashing even after the batteries are charged, or it could generate too much heat. Your only choice is to replace it with a new one. 

Voltage Fluctuations

Voltage plays a more key role than you think. If you are using those powerful high amp, high voltage chargers, then surely you need to charge when the voltage is stable. I have lost many devices due to voltage up and downs.

So, your charger might flash red lights because the voltage is either too high or too low. As I have said before, if it flashes fast, then it might be because the voltage is low. If it flashes slowly, then the voltage is high or vice versa, depending on your device. 

Abnormal Connection

You could be connecting the wrong power cable and expecting the batteries to charge. This will not only make your batteries, not the charger, but also it might be dangerous as the charger could blow up, Your battery charger could blink red lights because you placed the wrong cable or the connection is very loose. In a balance charger, if you have placed the faulty power cable, then it will beam red light constantly. 

Battery issue

You have at least once wondered if the issue is in your battery or not. Your battery could be damaged through disparity in your polarity, the cells are not balanced for the charger, or it could be your battery has gotten swollen. These are the standard indicator of a damaged battery.

The only visible issue here is the swollen battery. A battery typically gets swollen due to overheating or overcharging. It could be dangerous for your and your family’s health and the environment if you try to charge the swollen battery. Just get batteries that are reliable. 

Brand difference

Some batteries don’t specifically charge on any chargers. Those batteries require specific chargers of specific brands. You are probably using a different charger and getting agitated about why the batteries aren’t getting charged. Well, now you know.

If I had to think of an example, then what else than Duracell? Duracell batteries require either their own charger or chargers from relevant brands like Energizer. It may be able to charge from other chargers, but it won’t charge as efficiently as its preferred chargers. 

Non-rechargeable Battery

It is very likely that you have been using a non-rechargeable battery this whole time if you can’t relate to all the things I have talked about above.

Your charger is not detecting any source, but since something is connected to it, the charger is assuming some sort of malfunction, which is making its red light constantly flashing. This might be very dangerous as the battery could even get blown due to overheating. 

Frequently Asked Questions

How many volts is a fully charged battery?

For this, you require a multimeter that volts units. In general, if the battery has volts around 12.4 to 12.8 volts, then it is fully charged. As long as it doesn’t exceed 12.8 volts, you are good to go. 

How long can you use an AA battery?

You can sustain an AA battery for around three years if used correctly, given that it has 500-100 charges. 

Is there any way to make dead batteries work again?

Yes, a dead battery can be usable again, but its efficacy won’t stay like it was at the beginning. It can be done by altering its chemistry. You need to add electrons and add voltage to the batteries. The process is rigorous and complicated. 

What happens if you overcharge your battery?

When the voltage is too much, it will consume more power on your battery than it is supposed to. When you are done charging, the battery is supposed to show green light or red light, depending on the device. If you put it back on then, the charger might indicate that your battery is getting charged as the charger isn’t advanced enough to comprehend if the charger is fully charged after placing it again.

This will lead to too much voltage consumption in the battery leading your water electrolytes to decay, and naturally, your batteries will expire sooner than they should. The more heat gets produced, the current it will take, which might make the batteries explode. 

What happens if the energizer charger flashes red lights?

For the energizer charger, this usually indicates that the charger has not been attached correctly. It could indicate red light through mal-functionalities as well. 

Wrap Up! 

Hence, I hope you have now gotten a fair bit of understanding and a lot more about many devices on why the charges constantly flash red lights. I hope my insights have covered your device, and even if it hasn’t, chances are quiet a lot that you might find the reasons relevant to your device.

I have tried to cover almost all the aspects of most devices based on my knowledge and device, so I believe you are definitely going to be benefited after hearing me out. Thus, I hope you do better in life and help others in case someone else faces similar kinds of issues. 

Thank you, and it has been a pleasure! 

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