NiMH vs Alkaline

[daviddoria]

Can I charge Alkaline rechargables in a charger that says "nickel metal hydryde"?

what is the difference?

 

[Madmartin]

probably you can't.
the main difference with batteries is the chemical components that
react for thrusting electrons through your circuits.

for an alkaline this could (differences possible) be
Zn + MnO2 + 2 H2O + 2 OH- -> Mn(OH)2 + Zn(OH)4 2-

for Nickel/Cadmium it would be
Cd + 2 NiOOH + 2 H2O -> Cd(OH)2 + 2 NI(OH)3

for NiMh (Nickel-Metalhydride) it is:

NiOOH + MeH -> Ni(OH)2 + Me
where me is some special metal that can store lots of hydrogen.

The cell's chemistry differs a lot, so does the cell's voltage and the way
the completion of the charge process is detected.
AFAIK alkalines are charged with high current impulses, but I'm quite not sure.
I don't think you can charge an alkaline with a NiCd or NiMh charger.

BTW:
Anyone has seen a circuit for an alkaline charger ?

 

[droid]

hmm.. i don't think alkaline was designed to be rechargable

 

[stevez]

I've heard of rechargeable alkalines but have no experience with them at all.

Just a note of caution - be careful with any charger that might apply high current. Some Ni-Cad batteries can be charged at a very high rate so some chargers are made with that in mind. I recall that Ni-MH are to be charged at slower rate.

 

[keithwicks]

Ni-Cd and NiMH cells use constant-current charging. Alkaline rechargeable cells need a voltage-limited charger and will probably be damaged if left on a Ni-Cd charger.

A good source of information with lots of technical details is at:

**broken link removed**

The voltage-limited charger should be set to 1.65 volts per cell. Best performance is obtained by NOT running them down completely before recharging. Keep topped up if possible. No memory problem with these cells.
[/list]

 

[keithwicks]

Ni-Cd and NiMH cells use constant-current charging. Alkaline rechargeable cells need a voltage-limited charger and will probably be damaged if left on a Ni-Cd charger.

A good source of information with lots of technical details is at:

**broken link removed**

The voltage-limited charger should be set to 1.65 volts per cell. Best performance is obtained by NOT running them down completely before recharging. Keep topped up if possible. No memory problem with these cells.
[/list]