How to recharge alkaline batteries without exploding them

How to recharge alkaline batteries

You probably heard that it is not possible to recondition alkaline batteries. These are disposable batteries that can only be used one time – until it discharge. It can be found in any supermarket. Even thought common sense says you shouldn’t try charging them, there is a chance you can still revive them. That’s right – alkaline batteries can be recharged. But even if you managed to revive them, don’t expect it to last like the new ones. Energy it holds will likely be smaller that energy that the brand new batteries has. 

Recharging old batteries has its own advantages and disadvantages, we are going to talk about them:

Pros of recharging alkaline batteries:

  • You are saving the environment, alkaline batteries has less toxic metals. You are also reusing them instead of buying new ones.
  • Saving a few bucks as you don’t need to buy new batteries.

Cons of recharging alkaline batteries:

  • Charging them comes with additional risks.
  • Comparing with rechargeable batteries, it is not that effective, has less recharge cycles, lower capacity. After every charge cycle capacity that battery holds significantly lowers.
  • You need a special charger (charging non-rechargeable alkaline with regular charger creates additional risk).

As you might see, the batteries are not suited to be used as a regular rechargeable batteries (NiMH). Even though they can be recharged, recharging affects energy that battery can hold, every time it is recharged, it holds less and less energy. However the same is true about NiMH, but recharging affects alkaline batteries much worse. Energy alkaline battery can hold can decrease drastically only after a one cycle of charging.

Alkaline batteries can be recharged only about 10 – 20 times until it dies. Comparing to NiMH batteries that can be recharged hundreds of times, there is a obvious disadvantage of alkaline batteries in terms of recharging and re usage.

Is it safe to recharge alkaline batteries?

Well, this depends. If you know what you are doing, it is safe enough. If you use a special charger it is also safe.

But for most of the users, charging alkaline batteries with a aregular charger is not safe and not advisable. If you want to experiment, do it at your own risk, but it might be much simpler to order a pack of unused batteries online than to play with reconditioning.

There are rechargeable batteries on the market for a purpose. And these non-rechargeable alkaline batteries are created to last only once, until they discharge. Charging them can be viewed as a some kind of hack that is nor safe nor worth it.

Charging alkaline batteries can produce gas and high pressure that can explode the batteries. In most cases, high pressure results in an explosion. Even if you are ready to experiment with the process of recharging alkaline batteries, you should make sure that you took necessary safety precautions.

Batteries has to be charged in a safe place, preferably in an isolated environment where there aren’t flammable objects around and where the pretentious explosion won’t result in a large damage.

Is it cost effective to recharge batteries?

The thing with the alkaline batteries is that it can’t be fully discharged. It still has to have more or less charge. For example, devices that demands high power such as radios or cameras, drain power from the batteries completely. In this case, only option is to dispose of the discharged batteries, as it might not be reconditioned.

Devices like wireless computer mouses, however, don’t discharge batteries fully.

So the conclusion is that, the less batteries were used, the better condition they have as a matter of recharging.

When talking about cost efficiency, regular alkalines are unlikely to save you some money. As I already mentioned at the beginning of the article, these batteries can be recharged from 10 to 20 times until it completely dies.

Comparing to NiMH charge cycles (from 180 to 2000), that’s a small number. Buying rechargeable batteries is a lot more wise in the matter of money. NiMH batteries doesn’t cost that much, and it pays off more than buying nonchargeable alkaline batteries, recharging it for a few times, throwing away, buying new ones and repeating the process.

How to recharge alkaline batteries

The process is a pretty straight forward – you need to have suitable battery charger. There are plenty of chargers to choose from, but most of them are only for rechargeable batteries (NiMH or rechargeable alkaline). Make sure you have a universal charger (or the one that is specifically for non rechargeable alkaline batteries).

First step is to check if the battery is dead. As I mentioned, you can’t revive the dead battery. Easiest way to check if the battery is discharged is to make a bounce test:

Now this method won’t show if the battery is completely dead and is not rechargeable, you should use voltemeter for a precise evaluation.

When you know that your battery can be recharged, you should have a charger that can resurrect your battery.

Main problem with the regular chargers is that they overheat the alkaline. If you are careful enough, you can use regular charger, but make sure batteries are not overheating. Charge them near the place you are working that you could able to turn the charging process on and off. This lets batteries to cool down. However, total time batteries will be charged completely, will prolong. Now again, I not recommending you using this method.

The most safe method is to use a specific charger. You can find a plenty different chargers and they don’t cost that much. 

How I blew up my alkaline batteries and why you shouldn’t use regular NiMH battery charger to charge alkaline batteries

Now here is the funny story that you might also learn from. Few years ago, I found some electronic gadgets in my home that were not used for a while and decided I should recharge the batteries and use it for something else.

I knew that these batteries are rechargeable, so without any doubt I took out all the batteries from different gadgets (can’t recall what were these devices, but probably an old toy cars). I put them on regular charger and left charging.

I knew that these batteries were rechargeable so I have no worries about it. I left them charging for a night and went to bed. I know, that’s stupid. After some time (maybe hour or less has passed) I heard a boom.

One battery had exploded (you could charge 6 in this charger). And then I realized that two of the batteries that were put to charge were not rechargeable (just a regular alkaline).

If you are wondering how I managed to confuse NiMH and alkaline batteries, well, they looked the same. I mean they were manufactured by the same manufacturer, and you couldn’t separate them at first sight. However, if I would read what was written on it, I could avoid this incident.

Alkaline batteries exploded in the charger

This is how charger looks right now (I found it in my basement. He still works). As you might see, there is a switch on the charger that could saved my batteries from explosion 🙁 . This was definitely my mistake.

It looked way worse after the incident. So guys, I advise you don’t risking with regular chargers when charging alkaline. As you can see, there is a real chance it will explode.

How does alkaline battery chargers differ from regular rechargeable battery chargers?

Main difference is that alkaline battery chargers supply greater voltage across the battery. They also stop charging when the voltage reaches its peak.

Regular chargers shouldn’t be used for alkaline batteries as the battery likely will overheat and leak, or in a worse scenario, it will explode. There is no point of risking. You should use a specific charger for alkaline batteries.

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