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From: whit3rd on 25 Jan 2010 14:39
On Jan 24, 8:54 pm, terryS <tsanf...(a)nf.sympatico.ca> wrote:

>  That's what I was missing; the ampere hour capacity of the button
> cell. Amazing something with that small a volume can be 60ma/hr.

*cringe* No, it's 60 mA-hr! Monsieur Ampere capitalized his
surname, and so do we. Gratuitous use of the '/' character
where multiplication is appropriate is also ... points off. Correct
those units!

From: David L. Jones on 27 Jan 2010 01:37
terryS wrote:
> Have just replaced watch button battery from a package of five bought
> yesterday.
> The replacement cells are SR60W 1.55 volts. (Diam 6.8mm, depth
> 2.15mm.)
>
> Measured the removed battery (several years old now) open circuit,
> using a high input impedance DMM, at 1.486v. Doesn't seem that low?
> But that's off-load and it obviously run down because it doesn't make
> the cheap 'quartz' watch tick!.
>
> The first replacement cell was not functional at 0.948 volts. The
> second replacement at around 1.5v seems to work fine.
>
> Having introduced the topic/question can anybody comment on how much
> current these button type cells provide in a typical watch? Probably
> of the order of micro-amps?
>
> Nothing important but having now got involved one wonders!
>
> TIA. Cheers.

http://data.energizer.com/PDFs/364-363.pdf

23mAh nominal rating.

The problem is the increased ESR as the battery ages, it can't supply the
higher current pulses required to kick the hands.
No such current pulse issue with the same battery in a digital watch, unless
you turn on the backlight or something.

Dave.

--
================================================
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From: Charles on 27 Jan 2010 17:29

"Paul E. Schoen" <paul(a)peschoen.com> wrote in message
news:rem7n.2262$1m3.1738(a)newsfe11.iad...
>
> "Phil Allison" <phil_a(a)tpg.com.au> wrote in message
> news:7s5mkgFeu3U1(a)mid.individual.net...
>>
>> "terryS"
>>
>> Thanks for the info John:
>> That's what I was missing; the ampere hour capacity of the button
>> cell. Amazing something with that small a volume can be 60ma/hr. Guess
>> that is what the '60' in SR60W means!
>> And yes; if 3 years that's (60 x 10to minus 3)Ah./24 x 365 x 3 = Of
>> the order of 2.28 x 10to minus 6.Amps.
>>
>>
>> ** Shame that JF failed to say the calc gives only the AVERAGE current
>> drawn.
>>
>> The *peak current* draw at the moment of each "tick" is up to 100 times
>> higher.
>>
>> Has a big effect on the life span of the cell and what kind of cell ESR
>> value is tolerable.
>
> I suppose there might be a capacitor in there to handle the peaks.
>
> Paul

Good catch Paul.


From: Phil Allison on 27 Jan 2010 18:27

"Charles the Anencephalic Troll"
"Paul E. Schoen"
> "Phil Allison"
>>> "terryS"
>>>
>>> Thanks for the info John:
>>> That's what I was missing; the ampere hour capacity of the button
>>> cell. Amazing something with that small a volume can be 60ma/hr. Guess
>>> that is what the '60' in SR60W means!
>>> And yes; if 3 years that's (60 x 10to minus 3)Ah./24 x 365 x 3 = Of
>>> the order of 2.28 x 10to minus 6.Amps.
>>>
>>>
>>> ** Shame that JF failed to say the calc gives only the AVERAGE current
>>> drawn.
>>>
>>> The *peak current* draw at the moment of each "tick" is up to 100 times
>>> higher.
>>>
>>> Has a big effect on the life span of the cell and what kind of cell ESR
>>> value is tolerable.
>>
>> I suppose there might be a capacitor in there to handle the peaks.
>>
>> Paul
>
> Good catch Paul.


** There is never any such cap in a watch or battery wall clock

- you ASD fucked, parroting fuckwit.



..... Phil





From: Charles on 27 Jan 2010 18:40

"Phil Allison" <phil_a(a)tpg.com.au> wrote in message
news:7sc0fcFpp4U1(a)mid.individual.net...
>
> "Charles the Anencephalic Troll"
> "Paul E. Schoen"
>> "Phil Allison"
>>>> "terryS"
>>>>
>>>> Thanks for the info John:
>>>> That's what I was missing; the ampere hour capacity of the button
>>>> cell. Amazing something with that small a volume can be 60ma/hr. Guess
>>>> that is what the '60' in SR60W means!
>>>> And yes; if 3 years that's (60 x 10to minus 3)Ah./24 x 365 x 3 = Of
>>>> the order of 2.28 x 10to minus 6.Amps.
>>>>
>>>>
>>>> ** Shame that JF failed to say the calc gives only the AVERAGE
>>>> current drawn.
>>>>
>>>> The *peak current* draw at the moment of each "tick" is up to 100 times
>>>> higher.
>>>>
>>>> Has a big effect on the life span of the cell and what kind of cell
>>>> ESR value is tolerable.
>>>
>>> I suppose there might be a capacitor in there to handle the peaks.
>>>
>>> Paul
>>
>> Good catch Paul.
>
>
> ** There is never any such cap in a watch or battery wall clock

At the microampere level, it does not require much of a capacitor to smooth
out (supply) current peaks. And you will (of course not) supply
documentation that there are no such smoothing/leveling capacitors in
clocks/time pieces? Jackass.


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