I'm looking to replace some furry NiCd memory backup batteries with a silver
oxide primary button cell and a diode. The silver oxide cells are designed
for low drain applications and in 10 years time shouldn't die as messily as
the NiCds do.

The NiCd cells are vertically PCB mounted, so I'd like to try to fit the
buttons in their place. But I can't seem to find any button cell holders...
there are plenty of lithium coin cell holders (eg CR1220, CR2032) but these
are much too big for button cells like SR41, SR44 etc. I could possibly
bodge one of these (pad it out somehow) but that won't be mechanically too
stable. There are also clips which provide the positive electrode and are
designed to hold a button cell to negative-electrode-sized pad on a PCB -
but I don't have a PCB pad to attach one to.

So can anyone suggest any holders that I might use? Really all I need is a
suitably bent piece of metal with an insulating gap between each side, but
the problem is to get sufficient mechanical stability (so if it's dropped,
the battery doesn't pop out). Anyone have any ideas of how I might do this?

Thanks
Theo

On Oct 5, 3:20*pm, Theo Markettos
wrote:
I'm looking to replace some furry NiCd memory backup batteries with a silver
oxide primary button cell and a diode. *The silver oxide cells are designed
for low drain applications and in 10 years time shouldn't die as messily as
the NiCds do.

The NiCd cells are vertically PCB mounted, so I'd like to try to fit the
buttons in their place. *But I can't seem to find any button cell holders...
there are plenty of lithium coin cell holders (eg CR1220, CR2032) but these
are much too big for button cells like SR41, SR44 etc. *I could possibly
bodge one of these (pad it out somehow) but that won't be mechanically too
stable. *There are also clips which provide the positive electrode and are
designed to hold a button cell to negative-electrode-sized pad on a PCB -
but I don't have a PCB pad to attach one to.

So can anyone suggest any holders that I might use? *Really all I need is a
suitably bent piece of metal with an insulating gap between each side, but
the problem is to get sufficient mechanical stability (so if it's dropped,
the battery doesn't pop out). *Anyone have any ideas of how I might do this?

Thanks
Theo

IIRC Rapid electronics has a range of button cell holders


NT

Theo Markettos wrote:
The NiCd cells are vertically PCB mounted, so I'd like to try to fit the
buttons in their place.

Forgot to mention that one type is horizontally mounted, and quite
space-constrained (I have about 8-9mm diameter by 5mm height to play with,
so I'm looking at something like an SR41 cell). It might be possible to
make a land area for a negative electrode, but there's nothing to solder a
positive electrode to that'll give mechanical stability.

Theo

On 05 Oct 2010 15:20:41 +0100 (BST), Theo Markettos
wrote:

I'm looking to replace some furry NiCd memory backup batteries with a silver
oxide primary button cell and a diode. The silver oxide cells are designed
for low drain applications and in 10 years time shouldn't die as messily as
the NiCds do.

Don't forget to ensure that the silver oxide cells aren't 'charged'
like the NiCds.

--
Frank Erskine

Tabby wrote:
IIRC Rapid electronics has a range of button cell holders

Coin cell, but not button cell. This is the only button cell holder they
do:
http://www.rapidonline.com/Electrica...kw/button+cell

and that needs a PCB land area to match it, which I don't have. I could
make one out of copperclad, I suppose (I don't have etching facilities).
Thickness and weight of the PCB might be an issue too. (Anyone sell very
thin copperclad?)

Theo

Frank Erskine wrote:
Don't forget to ensure that the silver oxide cells aren't 'charged'
like the NiCds.

Hence the diode If I select the right one I can also drop the voltage
from 1.5V to 1.2V (though the chip being powered doesn't mind anyway).

Theo

On 05/10/2010 15:47, Theo Markettos wrote:
wrote:
IIRC Rapid electronics has a range of button cell holders

Coin cell, but not button cell. This is the only button cell holder they
do:
http://www.rapidonline.com/Electrica...kw/button+cell

and that needs a PCB land area to match it, which I don't have. I could
make one out of copperclad, I suppose (I don't have etching facilities).
Thickness and weight of the PCB might be an issue too. (Anyone sell very
thin copperclad?)

You can buy it as thin as tinfoil, but I can't help with sourcing it, sorry.

Dave

On Oct 5, 3:20*pm, Theo Markettos
wrote:
I'm looking to replace some furry NiCd memory backup batteries with a silver
oxide primary button cell and a diode. *The silver oxide cells are designed
for low drain applications and in 10 years time shouldn't die as messily as
the NiCds do.

The NiCd cells are vertically PCB mounted, so I'd like to try to fit the
buttons in their place. *But I can't seem to find any button cell holders...
there are plenty of lithium coin cell holders (eg CR1220, CR2032) but these
are much too big for button cells like SR41, SR44 etc. *I could possibly
bodge one of these (pad it out somehow) but that won't be mechanically too
stable. *There are also clips which provide the positive electrode and are
designed to hold a button cell to negative-electrode-sized pad on a PCB -
but I don't have a PCB pad to attach one to.

So can anyone suggest any holders that I might use? *Really all I need is a
suitably bent piece of metal with an insulating gap between each side, but
the problem is to get sufficient mechanical stability (so if it's dropped,
the battery doesn't pop out). *Anyone have any ideas of how I might do this?

Thanks
Theo

Buy a watch from the pound shop and butcher it for the battery holder.
You even get a free battery :-)

MBQ

Man at B&Q wrote:
Buy a watch from the pound shop and butcher it for the battery holder.

Hmm... not a bad idea. There's plenty of pound shop gadgets that use button
cells.

You even get a free battery :-)

And I get free electrolyte leakage all over my PCB in a few years too ;-)

Theo

Dave wrote:
On 05/10/2010 15:47, Theo Markettos wrote:
wrote:
IIRC Rapid electronics has a range of button cell holders

Coin cell, but not button cell. This is the only button cell holder they
do:
http://www.rapidonline.com/Electrica...kw/button+cell


and that needs a PCB land area to match it, which I don't have. I could
make one out of copperclad, I suppose (I don't have etching facilities).
Thickness and weight of the PCB might be an issue too. (Anyone sell very
thin copperclad?)

You can buy it as thin as tinfoil, but I can't help with sourcing it,
sorry.

Dave


http://www.megauk.com/pcb_laminates.php

In article ,
says...

Theo Markettos wrote:
The NiCd cells are vertically PCB mounted, so I'd like to try to fit the
buttons in their place.

Forgot to mention that one type is horizontally mounted, and quite
space-constrained (I have about 8-9mm diameter by 5mm height to play with,
so I'm looking at something like an SR41 cell). It might be possible to
make a land area for a negative electrode, but there's nothing to solder a
positive electrode to that'll give mechanical stability.


Use the clips you've already found. Drill two holes in the pcb either
side of the negative land area (or remove copper from around the holes
as needed) then solder a wire to the positive clip.

For the vertical holder, take a piece of insulating material (scrap pcb,
Formica, etc..) and two clips. bore four holes - i.e.. two holes at
right angles to the other two. *******ise one clip as required for the
negative terminal (cut off short support legs and some of the circular
area for isolation from the positive) and fit the other as designed for
the positive. Solder wires to the fixing tabs and connect as required.

If you have a suitable place on the pcb, mount it by soldering on of the
long negative tabs in place of the original holder.

As you've got 30 clips to start with, it doesn't matter if you make a
mess of it first time ...

--

Terry

Terry Casey wrote:
Use the clips you've already found. Drill two holes in the pcb either
side of the negative land area (or remove copper from around the holes
as needed) then solder a wire to the positive clip.

Ouch. Not on an 8-layer laptop PCB! This one is really space-constrained,
and mechanically very fragile (there's no other mounting than two small PCB
traces for the original NiCd and possibly some glue, but I can't glue in the
button cell). I'll have to think about it some more. Possibly a glued-in
base+clip might work, if I can find something thin yet rigid (and
non-metallic). Then copper screening tape for the connections.

For the vertical holder, take a piece of insulating material (scrap pcb,
Formica, etc..) and two clips. bore four holes - i.e.. two holes at
right angles to the other two. *******ise one clip as required for the
negative terminal (cut off short support legs and some of the circular
area for isolation from the positive) and fit the other as designed for
the positive. Solder wires to the fixing tabs and connect as required.

That's roughly what I was thinking of (and those have a lot more space to
play with).

As you've got 30 clips to start with, it doesn't matter if you make a
mess of it first time ...

I took a punt on a 'Signalex Personal Alarm' Poundland special, which takes
three LR44s. But it turns out they're in a stack with AA-style springs at
each end, so that doesn't help me. But I have some crummy LR44s now. Hope
I have time to blink before they leak

Theo