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Battery School Part 4 – What is NiMH?


When was the last time you interacted with a NiMH battery?

Probably not that long ago. You see, Nickel Metal Hydride batteries can be found in most wireless devices at home. Your electric toothbrush, landline cordless phone, shaver and so on. They are also in electronics where you might not think they are, like in the eCall in your car or in emergency lights. Otherwise, they are a common and more sustainable option to alkaline. Before NiMH, Nickel Cadmium would be commonly used but was swapped when the health risks of cadmium were discovered.


How is a NiMH battery constructed? The insides of a Nickel Metal Hydride battery are rolled up into a coil. You have the anode which is made out of hydrogen absorbing alloys (MH), the cathode which is made from nickel hydroxide (Ni(OH)₂), and an electrolyte made out of potassium hydroxide (KOH). NiMH batteries are common in both commercial and industrial use but are visibly separatable due to their flat, industrial, or protruding, commercial, positive terminal. NiMH cells have a low self-discharge rate less than 1% per month.

Pros and cons of NiMH NiMH batteries have plenty of pros and is the reason why it is so commonly used for rechargeable solutions. They are for an example a very safe rechargeable chemistry as they are made from non-flammable materials and are much easier to ship than lithium-ion cells as they don’t require UN 38.3 testing. Thanks to its safe construction you won’t need electronics to monitor the battery pack in terms of safety. To list a few other pros:

  • Modern NiMH cells have no memory effect.

  • They have a very good endurance.

  • They have a large temperature range and the possibility to recharge at negative temperatures.

  • NiMH cells are more tolerant to permanent charging.


Another great aspect of NiMH is that they are highly recyclable. In fact, it’s also easy to produce new cells with said recycled material, making them much more environmentally friendly than other rechargeable options.


If we were to mention some of the negative aspects, they would be that NiMH has a low energy density in terms of volume and weight, especially compared with lithium-ion. Another is that if you want to assemble the NiMH cells in parallel you need to have electronics to support the structure.


To end it off, NiMH is a safe and sustainable option for your devices that require a long steady discharge, especially in areas with wide temperature ranges. Are you interested in using NiMH for your project? Contact us here and we’ll help you right away.

*GP ReCyko is 94% recyclable.