only Ni-Mh batteries, a better man than I

On Tue, 30 Nov 2010 17:23:03 +0000 (UTC), "A. Baum" wrote:

On Tue, 30 Nov 2010 16:20:33 +0000, john gurney wrote:

Just bought a Duracell battery charger yesterday for rechargeable AA and
AAA batteries. (model no CEF24UK)

The first disappointment was that it only charges *two* AA or two AAA at
a time. (usually chargers of this size charge four batteries at a time).

When I got home it specifically says in the instructions only to charge
Ni-mh batteries, and not any others.

So I rang the free phone number and said I've got a lot of the older
Ni-Cd batteries (like you have...right?) and would it do any damage to
the batteries or the charger to charge them?

Could I get a straight answer, could I hell.

I was very persistant, but she would not answer in a straight way. When
I asked if I could be transferred to a technical department, she said,
"we have 'all' the information".

All you staring blankly out of the window, waiting for something to
happen...
It's a free phone number...... 0800716434

The question I kept repeating was, will any damage be done to either the
charger or to the older ni-cd batteries, if charged up in this charger?

If you can get a straight answer from this women you're a better man
than I.

NiCad and NmMh have different charge needs. Any idiot with a grain of
common sense knows this.

Actually, they're very close. The only important difference is that dV/dt
terminal charge sensing won't work on NiMH. Other than that they're *very*
similar.

Depends what you mean by 'damage' Arguably, most chargers do not quite get
it right, and either cook or take forever to charge the cells. I personally
find that all rechargeable, and I'm not including the so called
rechargeable alkaline here, are not as reliable as the manufacturers
suggest. Ni cads are low in capacity and go short, the ones you mention are
better but still suffer self discharge and wildly variable life and charge
potential in my experience. Only the lead acid sealed sort seem at all
reliable and the lithium, get so hot you need oven gloves to use them.

Brian

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Note:- In order to reduce spam, any email without 'Brian Gaff'
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"john gurney" wrote in message
...

Just bought a Duracell battery charger yesterday for rechargeable AA and
AAA batteries. (model no CEF24UK)

The first disappointment was that it only charges *two* AA or two AAA at a
time. (usually chargers of this size charge four batteries at a time).

When I got home it specifically says in the instructions only to charge
Ni-mh batteries, and not any others.

So I rang the free phone number and said I've got a lot of the older Ni-Cd
batteries (like you have...right?) and would it do any damage to the
batteries or the charger to charge them?

Could I get a straight answer, could I hell.

I was very persistant, but she would not answer in a straight way. When I
asked if I could be transferred to a technical department, she said, "we
have 'all' the information".

All you staring blankly out of the window, waiting for something to
happen...
It's a free phone number...... 0800716434

The question I kept repeating was, will any damage be done to either the
charger or to the older ni-cd batteries, if charged up in this charger?

If you can get a straight answer from this women you're a better man than
I.

On 30/11/2010 16:20, john gurney wrote:
Just bought a Duracell battery charger yesterday for rechargeable AA and AAA
batteries. (model no CEF24UK)

The first disappointment was that it only charges *two* AA or two AAA at a
time. (usually chargers of this size charge four batteries at a time).

When I got home it specifically says in the instructions only to charge
Ni-mh batteries, and not any others.
snip whinge

The correct answer is to clearly determine exactly what you need and
then take that specification with you when purchasing to ensure that you
are buying the correct item.

In article , A. Baum
wrote:
On Tue, 30 Nov 2010 16:22:14 +0000, Woody wrote:



The answer is no, it will not hurt the Ni-Cds provided the charge
current is within the range of the cells.

Uh, Nicads where charged mostly by time, NmMh by current sensing.

Erm, actually both types are "charged" by passing a current thought them.
:-)

The *sensing* of when they are fully "charged" can be done by various
methods (or none) depending on all sorts of details, etc.

Slainte,

Jim



You
would want to monitor a nicad very closely in a NmMh charger if it
didn't complain and abort the charge in the first place. My Duracell
charger will not charge Nicad. Not even attempt to charge them.

--
Please use the address on the audiomisc page if you wish to email me.
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There's been a lot of science in this discussion. My solution is
unscientific. I have a lantern that I use a lot. I made it myself
twenty-five years ago. It has four nicad D cells (the high capacity
ones). The bulb is a 5.95V one so the light is rather warm but the bulb
never fails. OK, it has done once or twice, over all those years. I
made a van charger which comprises a dropper resistor and a LED. The LED
is in parallel with a low value series resistor, so it glows when the
battery is actually being charged. The dropper value I can't remember,
but the charge rate is 125to 175mA, depending on whether the engine's
running. This conservative charge rate seems to work well. All I do it
put the lamp on charge when I've used it, and normally I take it off
when I get home. It always works when I want it to and the batteries are
the originals.
I have two very old RS nicad chargers. The have fixed charge rates of 9,
45, 150 and 350mA. I have occasionally charged the lantern overnight
with one of these at 150mA.

Bill

Bill Wright wrote:

There's been a lot of science in this discussion. My solution is
unscientific. I have a lantern that I use a lot. I made it myself
twenty-five years ago. It has four nicad D cells (the high capacity
ones). The bulb is a 5.95V one so the light is rather warm but the bulb
never fails. OK, it has done once or twice, over all those years. I
made a van charger which comprises a dropper resistor and a LED. The LED
is in parallel with a low value series resistor, so it glows when the
battery is actually being charged. The dropper value I can't remember,
but the charge rate is 125to 175mA, depending on whether the engine's
running. This conservative charge rate seems to work well. All I do it
put the lamp on charge when I've used it, and normally I take it off
when I get home. It always works when I want it to and the batteries are
the originals.
I have two very old RS nicad chargers. The have fixed charge rates of 9,
45, 150 and 350mA. I have occasionally charged the lantern overnight
with one of these at 150mA.

Bill

I've just realised I got this slightly wrong. I made a Mk I version 25
years ago, but the one I'm on about above was the Mk II version which I
made a few years later. I know that becasue in fact I made two, one for
Paul, and he lost it the little *******. And another thing. The Mk I
version was made in the days when nicads were a new thing, and I knew
nothing about them. I also had a more carefree attitude to safety in
those days, and that lamp had no fuses. The battery holder was a plastic
box. One day on the M18 the batteries shorted out. The van filled with
acrid smoke and the whole thing was a big scare. The incident caused me
to make the Mk II version, which is the one I still have. The Mk II
version has the batteries in a metal box, and there are two 10A fuses,
one half way along the battery chain and the other on the output (which
is a socket for connection to the lamp).

Bill

zzzzzzzzzz wrote:
On Tue, 30 Nov 2010 17:23:03 +0000 (UTC), "A. Baum" wrote:

On Tue, 30 Nov 2010 16:20:33 +0000, john gurney wrote:

Just bought a Duracell battery charger yesterday for rechargeable AA and
AAA batteries. (model no CEF24UK)

The first disappointment was that it only charges *two* AA or two AAA at
a time. (usually chargers of this size charge four batteries at a time).

When I got home it specifically says in the instructions only to charge
Ni-mh batteries, and not any others.

So I rang the free phone number and said I've got a lot of the older
Ni-Cd batteries (like you have...right?) and would it do any damage to
the batteries or the charger to charge them?

Could I get a straight answer, could I hell.

I was very persistant, but she would not answer in a straight way. When
I asked if I could be transferred to a technical department, she said,
"we have 'all' the information".

All you staring blankly out of the window, waiting for something to
happen...
It's a free phone number...... 0800716434

The question I kept repeating was, will any damage be done to either the
charger or to the older ni-cd batteries, if charged up in this charger?

If you can get a straight answer from this women you're a better man
than I.
NiCad and NmMh have different charge needs. Any idiot with a grain of
common sense knows this.

Actually, they're very close. The only important difference is that dV/dt
terminal charge sensing won't work on NiMH. Other than that they're *very*
similar.
It will and it does and a million RC modellers will tell you so, and the
manufacturers who make the chargers for BOTH.

Just because you have a charger that doesn't, doesn't make the principal
incorrect. It just means you have crap charger.

Jim Lesurf wrote:
In article , A. Baum
wrote:
On Tue, 30 Nov 2010 16:22:14 +0000, Woody wrote:

The answer is no, it will not hurt the Ni-Cds provided the charge
current is within the range of the cells.

Uh, Nicads where charged mostly by time, NmMh by current sensing.

Erm, actually both types are "charged" by passing a current thought them.
:-)

The *sensing* of when they are fully "charged" can be done by various
methods (or none) depending on all sorts of details, etc.


In all cases its done by sensing voltage.

Nickel cells drop voltage when fully charged.

Lithium polymer cells are fully charged at around 4.2v per cell.

Lithium iron cells its lower but similar. Leda acid is about 2.2v per cell.

The beauty of nickel chargers is they don't care how many cells are in
the pack. Once they detect a falling voltage, they can shut off.


Its been an issue with smart lithium chargers. A half charged 7 cell
pack that looks like a flat 8 cell pack wont last long if the charge
goes to 8x4.2v...:-)

john gurney wrote:
Just bought a Duracell battery charger yesterday for rechargeable AA
and AAA batteries. (model no CEF24UK)

The first disappointment was that it only charges *two* AA or two AAA
at a time. (usually chargers of this size charge four batteries at a
time).

When I got home it specifically says in the instructions only to
charge Ni-mh batteries, and not any others.
[snip]
From ://batteryuniversity.com/learn/article/charging_nickel_based_batteries

Good explanation about charging NiCd and NiMH batteries.
Near the end of the article one of the statements is:
"A charger for nickel-metal-hydride can also accommodate nickel-cadmium, but not the other way around. A charger designed for nickel-cadmium would overcharge the nickel-metal-hydride battery.

A well-designed charger is a reasonably complex device. Taking short cuts will cost the user in the long run. Choosing a well-engineered charger will return the investment in longer lasting and better performing batteries."



Please read the whole article for better info.

Buffalo