Rechargeable cells work at 1.2 V?

[Mark]

I was looking at some AA size rechargeable cells from Uniross.

See http://www.uniross.fr/UK/info/Booklets/0202
(table in PDF document: "Leaflet for rechargeable batteries 2004")

This literature and their product wrapping seem to say that their
NiMH cells deliver a maximum (nominal) voltage of only 1.2 V.

But I have some older NiMH cells (or maybe they are NiCd) cells which
I measure at 1.35V.

 

[Paul Hovnanian P.E.]

Mark wrote:

I was looking at some AA size rechargeable cells from Uniross.

See http://www.uniross.fr/UK/info/Booklets/0202
(table in PDF document: "Leaflet for rechargeable batteries 2004")

This literature and their product wrapping seem to say that their
NiMH cells deliver a maximum (nominal) voltage of only 1.2 V.

But I have some older NiMH cells (or maybe they are NiCd) cells which
I measure at 1.35V.

Maybe. The 1.35 V sounds like the peak (100% charged) voltage of a
NiCad. After a small amount of use, NiCads drop to around 1.2 to 1.25 V.

This isn't as much of a problem as it would seem, since NiCads (and
NiMH) have a much flatter voltage vs charge characteristic than typical
alkaline cells, so while a 1.5 V alkaline will slowly ramp down to about
1.0 V at end of charge (depending on the device being powered of
course), the rechargeable ones hang in at around 1.2 until almost fully
discharged. So most equipment designed to work with alkalines will be
designed to operate down below 1.2 V anyway.

--
Paul Hovnanian mailtoaul@Hovnanian.com
------------------------------------------------------------------
Bureaucrat, n.: A person who cuts red tape sideways. -- J. McCabe

 

[SAMMMMM]

possibly nicads.
the nimh cells are 1.2 volts.
i have 210 of them on my electric motorcycle.
sammmm


"Mark" <CANT_RECEIVE_MAIL@com.invalid> wrote in message
news:95BAB1811BE5D01A4D@130.133.1.4...

I was looking at some AA size rechargeable cells from Uniross.

See http://www.uniross.fr/UK/info/Booklets/0202
(table in PDF document: "Leaflet for rechargeable batteries 2004")

This literature and their product wrapping seem to say that their
NiMH cells deliver a maximum (nominal) voltage of only 1.2 V.

But I have some older NiMH cells (or maybe they are NiCd) cells which
I measure at 1.35V.

 

[Zorin the Lynx]

I had a Radio Shack CB walkie-talkie years ago that required either 10
NiCd AA cells or 8 alkaline ones; the alkalines would be used with two
"dummy cells" (basically a short circuit AA slug) so that they would
still fit.

I guess they couldn't design the radio to run well on 10 volts. Which is
probably annoying when using alkalines because it wouldn't take long for
eight cells to discharge to 10 volts in normal use!

-Z

Paul Hovnanian P.E. wrote:

This isn't as much of a problem as it would seem, since NiCads (and
NiMH) have a much flatter voltage vs charge characteristic than typical
alkaline cells, so while a 1.5 V alkaline will slowly ramp down to about
1.0 V at end of charge (depending on the device being powered of
course), the rechargeable ones hang in at around 1.2 until almost fully
discharged. So most equipment designed to work with alkalines will be
designed to operate down below 1.2 V anyway.

 

[Dimitrios Tzortzakakis]

Most devices either designed to work on ac or dc have a wide range of
operating voltages.I have measured the voltage of the mains and is usually
220 V (here).While, most radios, walkmans etc.are designed to work either
with alkaline or ni-cd batteries and use them to their full potential, thus
until they are completely exhausted.There are many circuits to stabilize dc,
as one learns in power electronics, including zener diodes, ICs transistors
etc.

--
Tzortzakakis Dimitri?s
major in electrical engineering, freelance electrician
FH von Iraklion-Kreta, freiberuflicher Elektriker
dimtzort AT otenet DOT gr
? "Zorin the Lynx" <yakko@zorin.org> ?????? ??? ??????
news:cpj6m5$rj2$1@ottoman.cs.fiu.edu...

I had a Radio Shack CB walkie-talkie years ago that required either 10
NiCd AA cells or 8 alkaline ones; the alkalines would be used with two
"dummy cells" (basically a short circuit AA slug) so that they would
still fit.

I guess they couldn't design the radio to run well on 10 volts. Which is
probably annoying when using alkalines because it wouldn't take long for
eight cells to discharge to 10 volts in normal use!

-Z

Paul Hovnanian P.E. wrote:

This isn't as much of a problem as it would seem, since NiCads (and
NiMH) have a much flatter voltage vs charge characteristic than typical
alkaline cells, so while a 1.5 V alkaline will slowly ramp down to about
1.0 V at end of charge (depending on the device being powered of
course), the rechargeable ones hang in at around 1.2 until almost fully
discharged. So most equipment designed to work with alkalines will be
designed to operate down below 1.2 V anyway.