What are NiMH batteries?

NiMH-batteries (Nickel Metal Hydride batteries) are a type of rechargeable battery that is widely used in different kinds of electronic devices. They are an improved version of the NiCd-batteries (Nickel Cadmium batteries), because they contain fewer heavy metals, making them more environmentally friendly. They also can store more energy and are less susceptible to a memory effect. This makes them very easy to maintain.

How to revive a NiMH battery

It can be possible in some instances to revive an old NiMH-battery at your own risk, but the success rate may vary depending on the current condition of the battery. If there is any physical damage like corrosion, bulging or leaks, it may not be safe to revive it.


Sometimes charging the battery can help. When the NiMH battery has been discharged for a long time and is completely empty, it might enter a deep discharge state. In some cases, cycling the battery might be the answer, by fully charging and discharging several times.


Some NiMH battery chargers, also known as a smart charger, come with a reconditioning or trickle charge feature. This applies a low current to the battery for a longer period, which can revive batteries that have been deeply discharged.


An empty NiMH-battery will have a low voltage. You can verify this by using a voltmeter. If the battery has 0V, it cannot be charged in a with a smart charger.


However, a NiMH-battery can be revived by using cables and another fully charged one. Connect one of the cables from positive of the fully charged battery to the positive of the empty battery. Keep them connected for three seconds and then disconnect them.


With the voltmeter you can see if the empty battery has now some voltage in it. Now you can put it in a smart charger again and it will start charging.

Can i replace NiMH with lithium-ion?

In most cases, NiMH-batteries (Nickel Metal Hydride batteries) and lithium-ion batteries aren’t interchangeable. They have different shapes, sizes and voltages most of the time. Sometimes a device can accept both, but this will most likely be mentioned on the product or in the manual.

Can you overcharge a NiMH battery?

NiMH batteries (Nickel Metal Hydride batteries) are more sensitive to overcharging, compared to NiCd batteries. Overcharging NiMH batteries can lead to several issues, like reduced performance and lifespan. In more severe cases, the battery can expand and leak.


You can prevent overcharging by using the proper charger. Most manufacturers of NiMH batteries (Nickel Metal Hydride batteries) recommend a certain charger for their batteries. You can also pay attention to the charging time and make sure avoid high temperatures while charging.

Do NiMH batteries have memory effect?

NiMH batteries, short for Nickel Metal Hydride batteries, are largely immune to the ‘memory effect,’ making them low-maintenance and needing little special attention. They are also environmentally friendly, lacking heavy metals in their composition.

How long do NiMH batteries hold a charge?

Most NiMH-batteries (Nickel Metal Hydride batteries) will lose their charge over a peroid of time when they aren’t being used. At regular room temperature, they will lose about 1% of their charge per day. That means that they will generally retain 70% of their charge after 30 days.

How long do NiMH batteries last in storage?

It is possible to store charged NiMH-batteries (Nickel Metal Hydride batteries), but they will lose their charge over a period of time. At regular room temperature, they will lose about 1% of their charge per day. That means that they will generally retain 70% of their charge after 30 days.

How long do NiMH rechargeable batteries last?

The lifespan of a NiMH-battery (Nickel Metal Hydride) can vary depending on several factors. In terms of charge cycles, low-capacity AA-batteries of to 2000 mAh can be charged up to 1000 times. Higher capacity batteries, like 2500 mAh batteries can only be charged for about 500 times.

How long to charge a NiMH battery?

The time that it takes for a NiMH-battery to charge may vary on factors like the capacity of the battery and the charger’s charging rate. We recommend referring to the specific charging instructions provided by the manufacturer of both your charger and batteries.

Lithium-ion versus NiMH

NiMH-batteries (Nickel Metal Hydride batteries) have certain drawbacks when compared to lithium-ion batteries. One drawback is the need for NiMH-batteries to be discharged once every two months. Li-ion batteries have several advantages over NiMH batteries. They demand no maintenance, suffer from no memory effect, undergo less self-discharge, and are marginally more compact due to their superior energy density. It’s worth mentioning that Li-ion batteries are more susceptible to heat.

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