Soldering directly to button battery

Why can't you just replace the 2032?

Or simulate one with 2 bits of tin-can and solder to those.

Put the battery in the freezer, and solder quickly. heat does shorten their life.

"john hamilton" wrote in news:i504ql$77j$ snipped-for-privacy@news.eternal-september.org:

I think you'll find that the discharged button cell will suck the new AAA's dry.

Also, the CR2032 is 3.6V. Three AAA's are 4.8V. I wonder what the voltage jump would do to your equipment.

Properly applied, the heat should do no damage. Some motherboard batteries used to be directly soldered-in.

A better approach, if you want a hard-wired battery receptacle, would be to unsolder the CR2032's battery-holder from the PCB, then solder the leads of your newly-purchased AAA battery-holder to the CR's holes PCB.

Correction: The button batteries had flat leads WELDED onto them which were then soldered to the motherboard. It's really kind of difficult to solder effectively to stainless steel. Direct connections to batteries are spot welded.

Not a good idea to leave any flat battery in place. Just about any type can leak. Also, it may try and re-charge off the new ones so drawing more current than necessary.

Out of curiosity why not just replace the CR2032?

There are warnings about charging lithiums and having them explode. I have never heard of it happening and have seen applications where they were being charged and nothing happened. (they must be very toxic-you need a label when shipping them)

battery (CR 2032) with two AAA batteries, I'm

I did this with a small clock mechanism. The button batteries were going out too fast. I just soldered to the original tabs though.

I've soldered to batteries many times. Heat a spot on the battery, leaeve a blob of solder. Tin the wire with solder. Reheat blob on battery, stick wire in blob, remove iron, hold very still while it cools.

Best approach is to replace the button cell. It'll most likely have the same or longer life anyway as it is pretty much just the shelf life that matters.

Those batteries typically last 5 years. 5 years from now the motherboard is going to be so obsolete, that once more replacement is all it might ever possibly need.

ote:

I missed that it was on a motherboard? I figured it was something else that was using it up at a faster rate.

And obsolescence is one of those very vague things; we have no way of knowing if the thing will be of no use to the OP in five years, and if it is then maybe it does make sense to fit a battery holder.

cheers

Jules

Yes, they can go bang when soldering if you apply too much heat for too long. Applying power to one probably isn't a good idea, either (you'd basically be trying to recharge an no-rechargeable cell - I doubt it'd outright explode or catch fire, but it might leak, and ever the vapours from batteries can make a real mess of PCB traces).

Personally I'd desolder it - preferably cutting it from the PCB first and then desoldering the legs that remain. What the device is would dictate whether I'd fit a direct replacement, or a socket, or trailing wires to a socket, or trailing wires to a holder to take AAAs etc.

cheers

Jules

Still run a pentium 2 from 1997? That's just two batteries ago.

Also: current draw is so low that it is self discharging that is the primary concern. A AA battery isn't going to last any more than the button cell.

Oh I have. Lots :-)

and have seen applications where they

They are not toxic, but they can pop nicely and start decent fires when shorted.

Actually, it will only last a fraction of the time the lithium coin battery lasted.

Li polymer batteries are worse, but you can find exploding button cells on Youtube if you look:

don't do it. make a dummy battery. A disk of double sided ecb material will work. solder to the copper, shim for thickness. Don't have a disk? use a nickel and a dime with insulation between. Depending on the socket, you may have to build up the diameter a little with solder.