Nickel Metal Hydride Batteries

[Bert45]

Before NiMH batteries we had NiCd batteries. So I know there was nickel and cadmium involved. Why are 'they' so coy about NiMH batteries? What does the M stand for? Obviously, I know it stands for Metal, but which of the many metals is it? Or can it be one of several metals? Or can there be more than one metal in one battery (apart from the nickel, obviously)?

[Calibax]

It's generallly a mixture of metals like lanthanum, cerium, neodymium, praseodymium, which is why it's just easier to put M

[EDDIE51]

^^ And all those metals are VERY expensive and VERY rare !
Which is why NiMH will only ever be for limited specialist use where cost is no object.

[KARL]

It is odd that, if NiMH is only for limited specialist use where cost is no object, NiMH batteries are currently the most common and pretty much only AA and AAA rechargeables (millions and millions in use, and they often last many years before being replaced with new NiMHs), plus C and D sizes also. The reason for dropping NiCd is that Cadmium is a heavy metal which is very undesirable in the wider environment - it is in effect quite toxic. Also, NiMHs do not suffer from the kind of "memory" effect that NiCds do.

[TheChair]

According to Wikipedia:
"Although lanthanum belongs to the element group called rare earth metals, it is not rare at all. Lanthanum is available in relatively large quantities (32 ppm in Earth’s crust)"
and
"Although neodymium is classed as a "rare earth", it is a fairly common element, no rarer than cobalt, nickel, and copper"

[Peter Pedant]

i knew they were rare earths

what I didnt know that the rare earth werent that rare....