Batteries Part 3 – a look at Nickel Metal Hydride Batteries
Kicking off with another macro shot – where’s the point of sharpest focus?
And so back to the batteries.
Nickel metal hydride batteries – (Ni-MH)
Most of my rechargeable cells now are of this kind and they do a great job from the photographic point of view – but they’re not perfect.
Nickel metal hydride batteries – (Ni-MH) have most of the characteristics of nickel cadmium cells, but with a number of improvements.
The main improvements are that they don’t have any toxic metals like cadmium, and they don’t suffer memory effects to the same extent.
This makes them the most widely used type of rechargeable AA and AAA cell today.
They still have one or two of the same difficulties as nickel cadmium cells.
They have the same 1.2 voltage and also a fairly high self-discharge rate. That is after charging, they can lose their energy quite quickly. This is worse in high temperatures.
This is particularly frustrating from the photographic point of view. There’s nothing worse than collecting the batteries you know you charged quite recently only to find they simply don’t have enough power and have to be charged again.
One lesser problem is that they can’t usually be charged quite as many times as Nickel Cadmium cells. Still recharging cells 500 times is still a great bonus in cost and environmental terms.
To summarize:
Against: They
have a nominal cell voltage of 1.2 v
self-discharge, i.e. lose energy after charging.
For: They
no longer use cadmium or other toxic materials
don’t have significant memory problems
are especially suited to high current drain applications like digital cameras and flashguns.
One point to watch out for is that they might need a dedicated charger
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