How to replace soldered CMOS laptop battery?

[techyguy717]

Actually I need to reset the BIOS of a laptop, so I just need to desolder one of the two leads for an hour. (So the bad BIOS config can clear)

I'm an expert computer technician, but an out of practice "Solder Certificate Holder".

I've removed the solder from the lead (using solder wick), but I can't get the lead up from the solder pad. The pad is big and the lead is as long as the pad. Because of the size of the lead I just cant seem to get it free from the pad.

I don't want to damage the board or nearby components with excess heat. What would you recommend? I don't have a hot air gun. I have a 25 Watt 750 degree Weller.

If I can't safely remove the lead, I'm about ready to clip off the battery, tin some copper wire, then solder it back on. Electrical taping the battery side onto the new wire leads.

 

[KJ6EAD]

Overcoming the heat sinking effect of all that metal, especially on the ground side will be nearly impossible with that low wattage iron. You need at least 80W and more would be better. Wicking the solder off of the surface only makes it more difficult to create a heat bridge from the iron to the solder inside the through hole that won't let go. Some technicians will use two irons together to get enough heat but that leaves zero hands for manipulation of the battery. You must have enough heat and thermal mass in the iron to heat the connection all the way through quickly or you will damage the board.

 

[Mikebits]

I would just cut the lead to the battery and this will allow you to desolder the lead from the board. You can re solder the new battery with wire and hold it down with an adhesive.

 

[picbits]

I'd cut one lead, bend the battery back slightly to allow the CMOS to reset then just solder the two halves of the lead back again.