|"Battery." World Book 2001 Edition. Book A-B: 171.||"A metal hydride cell can produce up to 1.35 volts."||1.35 V
|Panasonic Nickel-Metal Hydride Batteries. Digi-Key Corporation.||"Battery, Nickel-Metal hydride. 1300 MaH, 1.2 volts."||1.2 V|
|Sony Mini Disc Recorder Handbook: Model MZ-R90.||"Ni-MH Battery, 1.2 volts 1400 MaH."||1.2 V|
|Sony NH-14WM Rechargeable Nickel-Metal Hydride Battery.||[see images below]||1.2 V|
A nickel metal hydride battery is a new type of battery invented in 1992. Unlike alkaline batteries, nickel metal hydride (Ni-MH) batteries can be recharged up to 1000 times. A nickel cadmium (Ni-Cad) battery can also be recharged, but it would not not last as long. A Ni-MH battery can last up to three times longer than a Ni-Cad battery. Ni-MH batteries also do not suffer from memory loss. (Yes batteries have memory!). This means you could charge them partially and not experience any negative effects.
Nickel metal hydride batteries were developed to meet the requirement for increasingly higher levels of energy demanded by today's electronic products; for example: cell phones, CD players, mini disc players, and laptop computers. (The newer models of laptops use lithium-based batteries, which have a higher voltage and can last even longer than Ni-MH). Due to their increased capacity and energy density features, users can expect a longer time between charges and longer running time.
Ni-MH batteries use a special metal alloy that absorbs hydrogen as the anode's active material. This special alloy, usually nickel and lanthanum, can absorb over a thousand times it's own volume of hydrogen. The cathode used for a Ni-MH battery is nickel hydroxide. A standard nickel metal hydride battery can produced up to 1.35 volts, but usually operates at around 1.2 volts.
Front view of a Ni-MH mini disc battery
Side view of a Ni-MH mini disc battery
Alan Leung -- 2001