atomic wristwatch battery Q

[les]

hello...
I have an atomic wristwatch that after a year or so acted like the battery
was worn.
Specifically, the EL backlight (when depressed) would cause the numerics to
momentarily blank, and the clock to default to noon.
After replacing the battery, it seemed fine for a few days, and the symptoms
returned. Not suspecting anything, I bought a replacement watch by another
company (it had a different marking) but worked identically. Again the year
went
by and the story was the same. I bought the CR1620 at Walmart, and even
replaced that one within a week, and had this identical problem.
So this brings me now here.
I measured the current in 3 states:
quiescent: 3 uA, actively radio syncing: 180 uA, EL backlight : 5mA

When I used a AA 3 volt pack, the issue disappeared. Eveything was fine.
I suspect the current draw essentially drops the voltage below a theshold,
reseting
the watch. But is this normal? Can a lithium button cell be expected to
sustain
a 5mA draw momentarily and not reset a watch? Or am I constantly finding
poor quality lithium cells?
Suggestions? Perhaps a source for "good" button cells?

Les KA9GLW

 

[nvic]

Sounds like you have bad batteries. If another 3v source (such as the
AA pack) works, i think the batteries are going bad very fast and you
need to find that source of good lithiums. Hvae seen similar problems
in keyless entry remotes for cars - work for a year or two, die,
change batteries, work for a week or two and then die again. You just
need to find high quality batteries.

 

[JANA]

It sounds like you have a bad source for the batteries. The readings you are
getting seem to be normal for most digital watches of this type.

The backlight for the display can easily require a number of milliamps to
operate.

--

JANA
_____


hello...
I have an atomic wristwatch that after a year or so acted like the battery
was worn.
Specifically, the EL backlight (when depressed) would cause the numerics to
momentarily blank, and the clock to default to noon.
After replacing the battery, it seemed fine for a few days, and the symptoms
returned. Not suspecting anything, I bought a replacement watch by another
company (it had a different marking) but worked identically. Again the year
went
by and the story was the same. I bought the CR1620 at Walmart, and even
replaced that one within a week, and had this identical problem.
So this brings me now here.
I measured the current in 3 states:
quiescent: 3 uA, actively radio syncing: 180 uA, EL backlight : 5mA

When I used a AA 3 volt pack, the issue disappeared. Eveything was fine.
I suspect the current draw essentially drops the voltage below a theshold,
reseting
the watch. But is this normal? Can a lithium button cell be expected to
sustain
a 5mA draw momentarily and not reset a watch? Or am I constantly finding
poor quality lithium cells?
Suggestions? Perhaps a source for "good" button cells?

Les KA9GLW

 

[James D. Veale]

You might try gently cleaning the battery contacts with a pencil eraser.

 

[Sjouke Burry]

You might try gently cleaning the battery contacts with a pencil eraser.

Have you looked at your watch with a magnifiing glass or a microscope?
My watch had some very nice wiskers grown on the component board.
So the next battery was emptied in a real hurry!! Its in a landfill
now.