Ni-MH, or Nickel-metal hydride, is a battery technology based on nickel and metal hydride. The basis of this battery is the same as that of the NiCD technology. The advantage of the Ni-MH is the higher energy density than the older Ni-CD technology. For example, the capacity can be 2 to 3 times the capacity of a Ni-CD battery. This advantage can lead to a higher capacity in the same size battery, or a smaller battery with the same capacity. The lifespan of a Nickel-metal hydride battery is more limited than that of the Ni-CD, namely approximately 450 cycles. A major advantage of the Ni-MH battery compared to the Ni-CD is that no polluting raw materials are used.
The use
Ni-MH cells are very poor at withstanding deep discharges, unlike Ni-CD. In addition, the batteries are less suitable for machines that are not used often or consume little energy, such as remote bids. In that case, the self-discharge is greater than the energy consumption and Ni-CD are more suitable. Ni-MH batteries suffer less from the memory effect than Ni-CD cells, but are less resistant to high and low temperatures. A low temperature leads to loss of charge and a high temperature damages the cell. The quality and age of the battery determines the optimum temperature.
Charging and discharging the Ni-MH
Ni-MH has the major advantage of a shorter charging time compared to Ni-CD. The Ni-MH battery must also be fully charged when first used. For proper maintenance of the battery, it is recommended to fully discharge and recharge the battery once every 2 months. Failure to fully discharge the battery also leads to a memory effect with Ni-MH, but to a lesser extent than with Ni-CD. For a Ni-MH battery, the use of a suitable charger is very important. The charging technique for Ni-MH differs from charging a Ni-CD battery. A Ni-CD charger would give the Ni-MH battery an overboost and seriously damage the cell.
Why choose a Ni-MH?
- up to 40% more capacity than a Ni-CD battery
- More environmentally friendly
- Fast charging is possible
Why not choose a Ni-MH?
- High self-discharge
- Memory effect (but less than Ni-CD cells)
- Incorrect use may cause damage to the battery
