NiMH batteries or nickel-metal-hydride batteries are one of the best available rechargeable batteries in the market. Various benefits such as higher capacity, being less prone to memory effect and absence of toxic elements make them a favourable choice to use them when compared with other NiCd batteries.
Many appliances such as digital cameras, flashlights, high drain devices and even the first generation hybrid vehicles use NiMH batteries.
But it is difficult to buy these batteries again and again as they have issues like high self-discharge rate when compared with the NiCd and other batteries. They are even a bit expensive than the regular batteries which make the frequent purchase of these batteries a costly affair.
Because of these issues, some people opt for ways to revive them, instead of buying new ones again and again.
But, Is there a way to revive them? Can you revive NiMH batteries perfectly?
What about ideas like freezing them? Does freezing NiMH batteries to revive them work?
This article answers all your questions.
What are NiMH batteries?
A NiMH battery or Nickel-Metal-Hydride battery is a simple rechargeable battery. It has been invented as a replacement to NiCd rechargeable batteries which had issues like memory effect.
It has more benefits when compared with the old NiCd batteries.
NiMH batteries have more available charge than NiCd batteries and they last longer. They do not have the issue of memory effect in a significant way. The chemical Cadmium which is present in NiCd batteries is not environmentally friendly. This issue of the presence of toxic environmental chemicals does not arise in the case of NiMH batteries.
All these benefits make them an ideal choice for various uses. But still, NiMH batteries have the issue of high self-discharge rate when compared with NiCd batteries.
The idea of freezing NiMH batteries to revive them
This is one common practice followed by many people with the intention of preserving and enhancing battery life.
I have seen some people who store their batteries in their fridges in order to revive them.
But does this simple hack work for all kinds of batteries?
What about NiMH batteries?
Practically, in the case of NiMH batteries, there are no studies that tell you that, freezing batteries could revive them. Keeping your NiMH batteries in the refrigerator with an intention to revive them or recondition them may not help.
But there are many studies to show that the colder temperatures slow down the rate of energy discharge of the batteries. This is especially true with the case of NiMH batteries.
What is this energy discharge?
Every battery has a specific self-discharge rate at which the battery loses its stored charge. This loss of charge occurs even when you don’t use the battery.
The chemical reactions that occur inside the battery are the cause of this self-discharge.
This self-discharge occurs more rapidly when the batteries are exposed to hotter temperatures. NiMH batteries have a faster self-discharge rate when compared with other alkaline batteries. Because of this issue, it can be beneficial to store NiMH batteries in the freezer to cut down the self-discharge rate.
Storing the NiMH batteries at lower temperatures will slow their self-discharge rate to a great extent. These batteries could retain 90 per cent of their charge for at least a month when you freeze them. Or at least a cool place to store your batteries would be a better idea to minimise their self-discharge rate.
Precautions while freezing them
Although many battery manufacturers go against the idea of freezing batteries, many people have claimed the benefit of low self-discharge rate while freezing them.
Lack of proper precautions could cause various issues and further damage the batteries. Hence it is better to follow certain precautions while freezing your NiMH batteries.
1. Storing your batteries in the freezer can be a good idea, but storing them under extremely cold temperatures could damage the batteries.
2. Entry of moisture into the batteries could cause corrosion and damage the batteries. Hence it is always important to store the batteries in a sealed plastic bag so that they would not absorb moisture.
3. Avoid using the battery immediately after taking out from the freezer. Condensation could cause microdroplets to form on the battery. Hence it is best to bring them to room temperature before you begin to use them.