OT:Button Cell Batteries


B

Bill Stock

Not exactly on Topic for this group, but I'm not sure where else to ask.

I've got one of those digital appliance timers, which takes (3) 357A cells.
According to most sources the LR44 is a direct replacement for this battery.
But the LR44s I have for the cat toy (Laser Pointer) are much too thin. I
can buy 357As in 'The Source' in Canada, but the price is almost the same as
the timer itself. I'd hate to buy 357As online, only to find out that they
ship me LR44s or some other skinny substitute. Does anyone have experience
with these cells or know of an ACCURATE cross reference?

TIA.
 
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D

Doug Miller

Not exactly on Topic for this group, but I'm not sure where else to ask.

I've got one of those digital appliance timers, which takes (3) 357A cells.
According to most sources the LR44 is a direct replacement for this battery.
But the LR44s I have for the cat toy (Laser Pointer) are much too thin.
Better double-check your batteries -- one or the other isn't what you think it
is, because the LR44 *is* a direct replacement for the 357A. Same diameter,
same thickness.
 
B

Bill Stock

Doug Miller said:
Better double-check your batteries -- one or the other isn't what you
think it
is, because the LR44 *is* a direct replacement for the 357A. Same
diameter,
same thickness.
I guess my LR44s aren't to spec. The 357As are .22 inches thick and the
'LR44s' are .204 inches thick. This gives me a total difference of .048
inches or just enough to make them fall out.
 
G

Grandpa

Bill said:
I guess my LR44s aren't to spec. The 357As are .22 inches thick and the
'LR44s' are .204 inches thick. This gives me a total difference of .048
inches or just enough to make them fall out.
Then you don't have LR44s. Depending on your application, if its high
drain, you'll want SR44s. Anyway, take a look here:
http://en.wikipedia.org/wiki/List_of_battery_sizes
and see if you can understand what you actually have.
 
G

George E. Cawthon

Bill said:
I guess my LR44s aren't to spec. The 357As are .22 inches thick and the
'LR44s' are .204 inches thick. This gives me a total difference of .048
inches or just enough to make them fall out.
Go to a hobby store and buy a pack of brass
shims/flat sheets. Select the correct sheets to
make up the thickness you need or simply fold a
thin sheet to get the thickness and cut it out
with scissors. Best is to have it at the negative
end.
 
D

Doug Miller

I guess my LR44s aren't to spec. The 357As are .22 inches thick and the
'LR44s' are .204 inches thick. This gives me a total difference of .048
inches or just enough to make them fall out.
I guess *none* of your batteries are to spec. 0.22 inches is 5.6 mm, and spec
height for both the LR44 *and* the 357 is 5.4 mm.

I'll bet that all of these batteries are no-name made-in-China cheapies,
right? Try getting name brand batteries next time. They last longer, too.
 
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B

Bill Stock

Doug Miller said:
I guess *none* of your batteries are to spec. 0.22 inches is 5.6 mm, and
spec
height for both the LR44 *and* the 357 is 5.4 mm.

I'll bet that all of these batteries are no-name made-in-China cheapies,
right? Try getting name brand batteries next time. They last longer, too.
Yeah, the LR44s are eBay specials. Although they're certainly labeled LR44,
both on the cell and the shrink-pak. They work in the laser pointer, but not
for too long. Although $5 vs. a few cents goes a long way towards a somewhat
shorter life.
 
D

Doug Miller

Yeah, the LR44s are eBay specials. Although they're certainly labeled LR44,
both on the cell and the shrink-pak. They work in the laser pointer, but not
for too long. Although $5 vs. a few cents goes a long way towards a somewhat
shorter life.
I think you found the source of your problem...
 
M

mm

I guess *none* of your batteries are to spec. 0.22 inches is 5.6 mm, and spec
height for both the LR44 *and* the 357 is 5.4 mm.

I'll bet that all of these batteries are no-name made-in-China cheapies,
right? Try getting name brand batteries next time. They last longer, too.
Chinese-made batteries may be shorter because the land area of China
is greater than that of the US. So the cumulative gravitational pull
of the earth tends to compress things during the manufacturing
process. Sometimes they expand again after shipping, but usually they
don't.

This is also why Chinese people are usually shorter than Americans,
for example.
 
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Glad to hear the problem has been resolved.

A point which might be of interest concerning the short battery life and malfunction of digital callipers, is that it's most likely caused by using the wrong LR44 cells. (Using cheap alkaline cells instead of silver oxide). I've got three digital callipers of various makes - all of them budget types. They all work fine and the readings compare very closely. The instructions state that the battery must be a 1.55V silver oxide battery - the ones that the likes of Poundland et al sell are Alkaline. I don't know what the initial Voltage or the capacity of a new pound shop alkaline SR44 cell is, but if it falls below 1.45V in use, (which I dare say won't take long), the callipers will malfunction. Furthermore, silver oxide cells not only have a higher Voltage – they have a higher capacity.

I've only got one set of instructions now (for a Clarke/Machine Mart instrument) and here's what they state:

Quote:

8-<

Power Source: One silver oxide 1.55V LR44, capacity 180 mAh. Current <20uA

'Troubleshooting': Digits flash randomly or all five digits flash simultaneously: Battery Voltage below 1.45V.

Unquote.

8-<

When I bought the callipers, in all three sets, the LR44 silver oxide cell was stored in the little round hole in the foam till fitted. I keep a spare one in the hole in each one for when needed. Of my three callipers only the Clarke one has an on/off switch - the other two auto switch off when left alone for a few seconds, so I suspect that they go into 'sleep mode' and draw a minute current till next operated, because they 'wake up' the second that the slider is moved. (It would take a long time to reduce the battery Voltage of a 180mAh silver oxide cell from 1.55V to 1.45V at only <20µA).

It's easy to make a mistake when buying them, even though it does usually state either alkaline 1.5V or Silver Oxide 1.55V on the package.

EG, these are both Energizer brand, both LR44, and both packages look almost identical except for the small print:

1.5V Alkaline:

https://www.amazon.co.uk/Energizer-L...GXNDMMD3ETRRJ1

1.55V Silver Oxide:

https://www.amazon.co.uk/Energizer-S.../dp/B000IX2GXI

People often say “you can buy a sheet of calliper button cells for a quid at Pound Shops” but in fact you can't - not if you're buying the correct type of LR44 cell as per the instructions. Not all cells are created equal!

That said, I guess that the callipers are so evidently simple to use that few of us bother to refer to the instructions, which clearly state that you must use 1.55V silver Oxide cells – not 1.5V Alkaline cells. The discharge characteristics of each cell are quite different. Silver Oxide maintain their voltage to a point at which they fail. Alkaline – which are already below the stated 1.55V voltage needed by the callipers, taper off and soon fall below the voltage at which the callipers will operate.

Take a look at the graphs on the datasheets:

Silver Oxide:

https://www.murata.com/products/productdata/8809693806622/SR44R-DATASHEET.pdf?1615298419000

Alkaline:

https://www.celltech.fi/fileadmin/user_upload/Celltech/Prod.sheets/11186.pdf

Hope that’s of interest.

David.
 

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