How To Recondition NiMH Batteries : Best Ways Explained

Batteries are one of the simplest yet unnoticeable elements of our day-to-day life. From a mere television remote to gigantic automobiles, batteries act as the backbone to every mechanical and electrical device. 

There are different kinds of batteries each of them designed for a different purpose. Some batteries last for months, while some last for years. But apart from everything else, there is one thing that lies common between them – ‘reconditioning’. 

No matter how long a battery lasts, all of them can be brought to life. In other words, all of them can be reconditioned and the lifespan can be increased to a few more months or a few more years. 

Every battery is unique and hence all of them have a different process of reconditioning. In this section, we’ll be talking about ‘how to recondition NiMH batteries’. NiMH is the abbreviation of Nickel Metal-Hydride Batteries.

What Are NiMH Batteries?

A battery or a voltaic cell was invented back in1800 by Alessandro Volta, which was based on a simple concept of storing electrical energy in the form of chemical energy.

Ever since then, batteries have been used as a major power source in various industries. NiMH batteries and NiCad batteries can be categorized in the same section.

Both of them provide a long lifespan and perform efficiently. The only difference that lies in NiMH batteries is that instead of cadmium, they have hydrogen as an active element at a hydrogen-absorbing negative plate (cathode). 

Although the discovery of NiMH batteries is one of the recent past in the year 1986 by Standford Ovinhsky, founder of Ovonics. 

The idea of nickel-metal hydride batteries was found during the process of storing hydrogen in 1970. There were certain alloys that were known to form metal hydride and generate hydrogen ions in volumes up to a thousand times their own volume. 

Although now when technology is fairly advanced, NiMH batteries come into major use in the high-voltage automotive industry. In comparison to lead-acid batteries and NiCad batteries, the NiMH batteries contain 40 percent higher energy density. 

If you see the basic construction of NiMH battery – it consists of two electrodes, the negative terminal or the cathode is a hydrogen-absorbing alloy and the positive terminal or the anode is made up of nickel-hydroxide.

Both are electrodes are submerged in an electrolyte which is potassium hydroxide (KOH). The potassium hydroxide is less harmful in comparison to other chemicals used in NiCad or lithium-ion batteries. 

In comparison to NiCad batteries specifically, NiMH batteries are less susceptible to “memory effect” and are less harmful to the environment if disposed of. 

Why one Needs to Recondition NiMH Batteries

NiMH batteries are one of the most readily available rechargeable batteries in the market. Many companies have recognized the efficiency of NiMH batteries and companies like Panasonic, Duracell, Energizer, and Rayovac offer NiMH batteries in AA and AAA sizes.

With the array of benefits that come along with NiMH batteries, they are obviously more expensive than lead-acid batteries and NiCad batteries

Buying a new NiMH battery every time it dies off would prove to be a bit hard on your pocket. NiMH batteries are efficient and are less prone to voltage depression, and if someone knows how to effectively recondition NiMH batteries, they are relatively gonna save a lot of bucks. 

The process of reconditioning NiMH battery is quite easy and can be done by anyone. It doesn’t require high technical skills to be executed smoothly.

How To Recondition NiMH Batteries?

If you want proper knowledge about battery reconditioning, you must checkout EZ battery reconditioning as it has provided some trustworthy methods as the below method may not work for a lot of people

You must first have some basic tools such as the voltmeter, two spare wires, crocodile clips, and a nickel-metal hydride battery regenerator.  

Connect the battery with the voltmeter to take the readings, if the voltage is showing 1.0 volts or less – the battery is completely drained out.

If the voltage of the battery shows 1.2 volts, the battery just needs to be charged. Here there are two existing cases.

Step 1: Use a Battery Regenerator

Battery Regenerator

In case your battery voltage reads 1.2 volts, take a good quality battery regenerator and let the nickel-metal hydride battery charge for the next 6 – 8 hours to complete its one full recharge cycle. 

Step 2: Complete Discharge

After the battery has gone through a complete charge, let it discharge completely. Now charge it completely again and seal it in an air-tight bag.

Put the air-tight bag to freeze for the next 2 – 3 hours. After freezing, allow the battery to come to room temperature. The battery is now ready to use.

What To Do When Voltage is Less Than 1V while Reconditioning NiMH Batteries?

Nickel-metal hydride batteries have a ‘sleep-mode’ mechanism whenever the battery is left discharged for too long at a stretch. You need to give it a shock.

The process of shocking is simple, you will need a different power source – you can use a NiCad battery, spare wires, and crocodile clips. 

Now use the crocodile clips to connect the NiCad battery with the dead NiMH battery – positive with the positive terminal and negative with the negative terminal.

Now, while connecting the negative terminal just tap on the terminal with crocodile clips for the electrical pulses to go through the dead battery.

Repeat the tapping process for 10 – 15 times. Use the voltmeter to recheck the voltage, after shocking the voltage would spike up to 1.2 volts again.

Once the voltage is back to normal, you can use a battery regenerator and charge it for the next 6 – 8 hours for it to work perfectly, with full efficiency. 


After the rise of lithium-ion batteries, nickel-metal hydride batteries are very less in use. They serve greatly to the high voltage industry sector.

NiMH batteries are built on a great concept, well designed for a low-manufacturing cost product and the least harmful to the environment, compared to all other batteries.

Reconditioning NiMH batteries are relatively easy and they have a big lifespan. Reconditioning only increases its uses three to four times more. 

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