the do's and dont's on battery replacements for a newbie

[aladdin_sane]

OK so imagine I have the watch and need new batteries and I know which sort of batteries I need.

I'm sat here looking at the back of the watch, what would I do next? Please list tools used, things to watch out for.

I'm not talking about any specific watch. I'm looking for general advice. I know there's watches where the whole back comes off and then those with battery hatches.

[rewolf]

I know there's watches where the whole back comes off....

Yes, and these alone can be either a screwed back (either the whole back or some threaded ring), back screwed down with 4..8 screws, or simple pop-off. Tool needed depends on the watch, so general advice is difficult (lengthy). Simply put: you need a tool that fits


Avoid ESD (electro static discharge):
Perfect is an earthed workplace with your wrist connected to it, there are special conductive wristbands for that purpose.
I stick to the following simple rules and have NEVER fried anything by ESD though I handle "naked" electronics every day:
- No woolen or synthetic clothing, chair upholstery, or carpet - this avoids electrostatic charge buildup in the first place and makes earthing rather unnecessary.
- Sit down and before you touch anything earth yourself somewhere. A power plug with only the earth contact connected is perfect for that purpose - of course at the beginning it's a strange feeling to touch the end of a wire that leads directly to a mains plug


No sweat on your hands. If you have sweaty hands, use thin cotton gloves.


Observe correct battery polarity.


Avoid handling batteries with metal tweezers, and if you do, be careful not to short them.


Dont try to sqeeze too thick batteries into a watch, it might break you module.


Be careful - don't touch or remove anything you don't have to.


You wrote "I know which sort of batteries I need", but I can't refrain from singing my song:
Use AgO batteries for LED watches.
In the long term, Silver Oxide is better than Alkaline for LEDs because they retain their 1.5V until the end. Alkalines decay from 1.5V down to 1.0V from the very first day, so the watch gets dimmer by time. The nominal capacity (mAh) isn't much different, but the voltage delivered.
Note that the Silver Oxides come in 2 flavours: low drain and high drain. High drain (KOH electrolyte) is obviously better for LEDs - it usually has "SW" ending, low drain "W" (Maxell code).
The only disadvantage is that the end comes almost without warning - only a few days after you notice it get s dimmer it finally dies.
Links to battery charts are here: http://dwf.nu/viewtopic.php?t=2583

[aladdin_sane]

thanks for the advice. Having looked online at battery prices, I can replace for a 1/3 of what it would cost to have it done in-store so it makes sense especially as I get to choose which brand/type of battery I want to be using.

I'm looking at buying some narrow blade screwdrivers for popping off the battery compartments.

I intend to experiment on an old LCD before I need to attack a precious LED. :)

[rewolf]

...I'm looking at buying some narrow blade screwdrivers for popping off the battery compartments.

For the pop-off back type better use a special case opener tool, looks like a pocket knife, don't know the exact name.

BTW do you work for National Semiconductor?

[aladdin_sane]

...I'm looking at buying some narrow blade screwdrivers for popping off the battery compartments.

For the pop-off back type better use a special case opener tool, looks like a pocket knife, don't know the exact name.

BTW do you work for National Semiconductor?

no but I'm a fan of their watches/modules. :)

[retroleds]

Observe correct battery polarity.

If there is a question about which way the batteries go, sometimes just looking closely how the battery holes are shaped at the bottom will make it clear. The one that has a sharp corner in the bottom is positive down, the one with a "corner break" or chamfer/bevel in the bottom is negative(-) down.


Aladdin_sane - love that avatar!!

[aladdin_sane]

Aladdin_sane - love that avatar!!

Thanks I needed something appropriate for a digital watch forum and thought it fitted fine though a friend thought it represented nationalist political beliefs but it doesn't. I'm very liberal. :)

Thanks for the battery polarity advice. :)