do rechargeable batteries not work in all appliances?

[zebedee]

Specifically a Petzl headtorch - Duracell Alkaline throw-aways are fine, fully charged NiMh - nothing. What is going on?

[Le TVR]

NiMH are about 1,25 volts
Alcaline about 1,5 volts

Sometimes that small difference can be all it takes, especially with LED type lights.

[southendpier]

interesting. I cannot get the tumbledryer to work on standard ni-cads, going to upgrade later to nimh. I reckon that with a rub of emery on the contacts and the right ambient temperature we could get a result.

[zebedee]

Spot on, never noticed. Can you get 1.5v rechargables or not?

[zebedee]

southendpier said:

interesting. I cannot get the tumbledryer to work on standard ni-cads, going to upgrade later to nimh. I reckon that with a rub of emery on the contacts and the right ambient temperature we could get a result.

I see what you have done there. I meant 'applications' (I think)

[southendpier]

zebedee said:

Spot on, never noticed. Can you get 1.5v rechargables or not?

yeah, some wireless phones use them. Bit more expensive, probably need to go to a maplin to source.

[zebedee]

southendpier said:

zebedee said:

Spot on, never noticed. Can you get 1.5v rechargables or not?

yeah, some wireless phones use them. Bit more expensive, probably need to go to a maplin to source.

Thats where I got the 1.2V ones from, never mind, they were half price and there is lots of other stuff to use them in!

[cj_eds]

Seem to think that some will provide a higher continuous current than others. Dunno where I heard that, but given their different chemical properties it could be right.

[rsv gone!]

Le TVR said:

NiMH are about 1,25 volts
Alcaline about 1,5 volts

Sometimes that small difference can be all it takes, especially with LED type lights.

Especially if there are several batteries. The difference is multiplied.

[jeff m]

Due to charging differences it is also not possible to "upgrade" from Nicads to Halides in solar applications even though the voltage is the same.