NiMH stands for nickel-metal hydride, which is one of the most successful batteries in history. It uses the same nickel-hydroxide positive electrode and KOH electrolyte as the Nickel-Cadmium battery but uses hydrogen gas to replace the cadmium in the negative electrode. The nickel-hydrogen battery is mostly used in low-orbit satellites, which charge and discharge the batteries on every pass around the earth, and requires a long cycle-life battery. Nickel-hydrogen cells have a cycle life of tens of thousands of cycles.
There are a number of charging methods that can be used with nickel-metal hydride batteries, although sometimes this isn't as straightforward as other types of cell or batteries. NiMH cells, similar to NiCds require charging with a constant current with the rate of charge typically specified on the case of the cell, with this rate not to be exceeded. Within the boundary of constant current charging, there are a number of techniques
NiMH batteries from Vapextech can, for most applications, be a substitute for alkaline batteries despite their voltage differences. Alkaline batteries are rated at 1.5 volts and they will only deliver 1.5 volts when fully charged. As they start to discharge the voltage of alkaline batteries will continue to drop.
Over the course of their discharge, alkaline batteries average roughly 1.2 volts (very close to the voltage of a NiMH battery). The main difference is that an alkaline battery starts at 1.5 volts and will gradually drop to lower than 1.0 volts. NiMH batteries will stay at about 1.2 volts for most of their discharge cycle.
There are a small number of cases where their actual voltage difference is crucial. For devices such as a radio, where a higher voltage means a stronger signal, you could opt for an alkaline battery, although they are more expensive than rechargeable NiMH
Our team often get asked if you can use NiMh (Nickel Metal Hydride) batteries in solar lights that currently use NiCd. Luckily you can and we will explain the benefits of making the switch during this blog.
Here are four reasons why you should choose NiMH batteries -
Long Shelf-Life - New NiMh batteries can remain unused for anywhere between 3 and 5 years. Vapextech recommends using your NiMH rechargeable batteries sooner to keep your solar lights shining bright.
No Memory Effect - NiCd batteries do have issues attaining a 'memory' that reduces the life of the battery. NiMh