Why is my rechargeable battery charger blinking red

A flashing red light on the charging base means that the charging base is outside the normal operating temperature range. Move the charging base to a location where the temperature is within range, between 10°C (50°F) to 40°C (104°F).

Having so many digital devices means you would need lots of rechargeable batteries. Since rechargeable battery can be expensive so I would try to maintain and extend the battery life as much as possible. Sometimes it was just too bad the battery has reached the end of their lifecycle when my battery charger was blinking which indicate a dead battery.

Why is my rechargeable battery charger blinking red

Once a rechargeable battery is dead there was no way to revive it. Somehow some battery brands seemed to last very long while others seem to go to the grave much faster. Well, how long a battery last will depends on how often it was used, how deep the charge, how great the drain when using it on your devices.

My rechargeable batteries were mostly to be used with my digital cameras. However, I’m not always romping around taking lots of photos. Occasional travels and special occasion once in a while meant that the batteries are not being constantly used. And when it is used, the digital cameras and related photography equipment are high drain devices. So it is good to keep the batteries charged up on standby for any photographic opportunity.

I read somewhere that a normal battery loses its power about 10% per year. While a rechargeable battery after it was fully charge will lose anywhere from 15% to 25% of its charge in a year, though the newer NiMH ones could retain their charge longer than the standard NiMH types. As for the Lithium Ions, their self discharge rate is rather minimal, the only problem with them was the aging issue, even while not in use, the battery would spoil after a year or two. Though I do get a good lifespan out from them for my mobile phones which on most time last me about 2 to 3 years before needing a replacement.

Lithium Ions are more expensive than the conventional AA/AAA NiMH batteries. But in the end I found that once you started using the rechargeable battery it is best to use it frequently, because in the end the battery would lose its ability to keep its charge due to its aging issue.

I also noticed that if I were to use the battery until it was totally drained of energy, it would spoil the battery. I’m not sure if my observation is correct or whether the AA/AAA rechargeable battery has reached the end of its rechargeable cycle, but 500 times is quite a lot, I don’t think I have ever hit even the 100 charge cycle for my batteries!

So a few days ago, I started recharging some of my batteries which I have not recharged them after using them on my digital cameras after my trips and travels. It was an overly fully drained battery for my Panasonic Lumix TZ7 digital camera. This was a compatible Li-Ion battery, not the original as it was cheaper. But the charger just kept blinking indicating the battery was dead. Fortunately it was still within its one year warranty, so I could get a new set.

I also recharged my UNIROSS AA batteries which were left empty in my battery case that I forgot to charge up, and they too were dead battery as my charger just kept blinking. Same goes for my GP AAA rechargeable battery, they were drained and were left uncharged for a long period, and when I tried to charge it up, blinky lights ensued.

Oh, well, there goes the batteries, I hardly used them and they were now knocked out! So based on the above observation, I suppose even if I were not using them, I should charge them up and keep them away. However I should think for those rechargeable AA/AAA batteries, it would be better not to just store them, but to find some use for them in any devices or electrical equipment or even children toys!

For specialized Li-Ion batteries for digital cameras, you just have to use it regularly and check on it, while the AA/AAA rechargeable, use them in flashlights (which are not really high drain unless prolonged usage), or use them on children toys (some of which are rather high drain, just make sure your spouse didn’t throw them away after the power has been depleted!).

So to avoid blinking lights in the charger which means dead battery, best to use them often and charge them up regularly once you’ve bought them from the store!

It’s typical for the rear batteries to get warmer than other available banks. The two batteries tend to become warmer compared to other chemistries because of heat produced by the charger’s converter circuitry. This doesn’t imply that the batteries overcharged or charged faster compared to others.

This is normal and the charger will show different flashing lights, each portraying a specific meaning. The inbuilt converter circuitry plays a vital role in determining the flashing light based on the status of the battery. For this reason, this article will try to educate you on the meaning of the flashing red light on the battery charger.

Table of Contents

  • Why am I seeing the flashing red light on my battery charger?
  • The battery charger CHARGE light blinks when charging your battery pack
  • Frequently asked questions (FAQ)
    • Why is my battery charger flashing green and red?
    • How should I notice that my battery tender is faulty?
  • Conclusion

Why am I seeing the flashing red light on my battery charger?

Restoring bad batteries is what I can begin by as the meaning of blinking red light in my battery charger. This happens occasionally, whereby the charger displays a flashing red light that indicates bad batteries. Experts recommend various methods of restoring batteries that won’t be charged using a battery charger.

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In case you insert the battery and you see the red light blinks at an interval of 5 seconds, the voltage of the battery is too high. It is a clear indication that your chemistry requires a restoration, or else, it can’t be charged. So, if you see such an indicator, just know that the battery might be full or bad.

Sometimes the battery might be having a full charge, but still, need charging. In such a case, you are supposed to ensure the batteries are completely drained before trying to charge again. Draining the battery is one way of restoring ‘bad batteries’ and is the simplest way.

Why is my rechargeable battery charger blinking red

On the other hand, you will start to see a flashing red light at an interval of 90 seconds immediately after connecting the charger. This issue happens mostly when the battery is over drained, leaving it with no volts. Therefore in such situations, it’s advisable to allow the chemistry to stay on charging for a few minutes.

You don’t have to worry about this 90-second flashing red light because it simply implies that the voltage of the battery is too low. Leaving it on the charging will help strengthen the cells, respond to charging and pick normal operations. I would advise you to leave the batter overnight on the charger while the red light continues to flash.  Detach the battery and give it another try to see whether it picked or responded to charging.

You will continue to see the red light even after unplugging the charger. If it’s irritating, you are required to detach at least a single battery to let the light go off.

There are several reasons that may force the charge light display differently. Some of these reasons include:

The surrounding is too icy to charge your battery pack. If you are operating in winter or any cold environment, the battery charger light will blink red. You can change such a situation because of its nature, but you can place your battery on a stand that’s either one or two feet above the ground.

The battery pack hasn’t been in service for a long period. Of course, you will start to see a red light flashing immediately when you insert a battery on your battery pack that has been dormant for a while. Handling such a situation is simple as you only have to expose the pack to the electricity for some hours before reinstalling the battery for charging. It is as simple as that.

Another reason that you are seeing a flashlight on your battery charger is that the connection between the charger and the battery is very poor. Try to check if the wires are not correctly fixed and put them in place.

You should also want to ensure that the battery terminals are in good working condition, free from acid accumulation. I would advise you to rotate the terminal clips or wires, rubbing them on the terminals to ensure they are tightly held in place.

Therefore, if you connect the AC power cord to the outlet and in case the ring terminals or alligator clips aren’t plugged into the battery, probably the green and red lights will be seen. More so, in case you connect the ring terminals or alligator clips together, the art will lack an electrical spark.

Furthermore, the green and red lights will blink alternately when you hook the charger backward. The suitable solution to curb this issue is by connecting the ring terminals or alligator clips to your battery with proper polarity.

In short, connect the Red wire to the positive terminal and the black wire to the negative battery terminal before initiating the charging process. The red light on steady means that the charger is correctly connected to the battery and charging is initiated. Once the battery is fully charged, the light will go off; only if you disconnect the battery.

The battery pack itself might be problematic. Here is another reason that you might be seeing red flashing lights on your battery charger. Try fixing the problem before returning the battery again.

Frequently asked questions (FAQ)

Why is my battery charger flashing green and red?

The green and red lights sometimes alternate to imply that the battery is bad or the 72-hours safety Timer is activated. Besides, it may imply that a good, very large chemistry isn’t charged completely. Or that relatively smaller chemistry is defective.

How should I notice that my battery tender is faulty?

Turning on the vehicle’s headlights to check for voltage is the best way out. In case there’s a 12.7 voltage reading, just know that the battery is completely charged. Otherwise, anything under 12V reading like 11.5V implies you have a faulty battery.


You need to understand that the LED light at the 12DC power input blinks solid red while charging and green when completely charged. Hopefully, you have seen the various meanings of the flashing red light and the popular one is the restoring ‘bad batteries’. It also implies that the battery can’t be charged because it’s full or it’s the temperature is too cold.