RTC/BIOS battery replacement - Page 1
Forum section: electronics / repair

author: Messtechniker
author_rank: Frequent Contributor
timestamp: August 01, 2017, 06:34:13 am
content: With some equipment, the RTC/BIOS battery, specifically a CR2032, is difficultto reach because physical access is restricted by other components or plug-in boards which I would not like to remove in the field. Moreover, I don't like the idea of the battery bouncing around after having released it.Therefore my question: Does a tool exist to safely extract a CR2032? Something with a suction cup at the end of a rod perhaps? Or some sticky tape at the end of rod? What would you recommend?

author: Rbastler
author_rank: Frequent Contributor
timestamp: August 01, 2017, 06:38:01 am
content: Would it work if you build a suction tool out of a a desoldering hand pump ? Put a rubber pickup piece on it and with a stick or so release the battery and pick it up with the before mentioned tool.Edit: Or a SMD placemet tool could work too

author: Kjelt
author_rank: Super Contributor
timestamp: August 01, 2017, 08:52:09 am
content: There are many different pcb mount button cell holders made, they need slightly different techniques to remove the buttoncell, but most have small mechanical bulges to keep the battery in place.So vacuum suction without additional mechanical tool to help remove it from the holder will probably not work.

author: carl_lab
author_rank: Frequent Contributor
timestamp: August 01, 2017, 11:08:08 am
content: Piece of duct tape?

author: Ian.M
author_rank: Super Contributor
timestamp: August 01, 2017, 11:52:14 am
content: Coin cells have a steel case so you can use a high power magnet glued to a tongue depressor or long lolly stick to capture the coin cell as soon as it comes free, (or if possible attach to it while its still in the holder), + whatever tool works best to pry the coin cell free from its holder without damage.You may need a second tongue depressor to 'guard' the face of the magnet while getting it into position so it doesn't stick too hard to any steel parts or ferrite cores while you are getting it into place.A similar tool combo can be used to insert the fresh cell, though the pry tool would probably be best replaced by a stout chopstick with a notched or stepped end for pressing the cell into place.

author: Messtechniker
author_rank: Frequent Contributor
timestamp: August 01, 2017, 01:31:39 pm
content: Thanks Ian.M for pushing me in the right direction.Since I have a magnet on a stick anyway, I thought I'd try.Works nicely.See pics using a dead motherboard with noneed for ESD protection any more.With some coin cells the suction method will probably notwork since the coin type can be slightly engraved.

author: Kjelt
author_rank: Super Contributor
timestamp: August 01, 2017, 01:38:05 pm
content: Quote from: Messtechniker on August 01, 2017, 01:31:39 pmThat is a question of vacuum volume, you do not need deep vacuum just a pump that has a large volume capacity. I have a festool vacuumpump that can hold a MDF wooden plate and this just leaks (you can feel the vacuum go through the wood) still it works as a charm. For a coin cell that would be overkill ofcourse but you get the picture. But if the magnet works that saves a lot of hassle.

author: Ian.M
author_rank: Super Contributor
timestamp: August 01, 2017, 01:39:54 pm
content: Yes. that's great if you've got straight line access from above, but if the cell holder is between two PCBs, mounted on one of them, you'll need the magnet on the side of a tongue depressor or similar stick - at a pinch, stuck directly to a flat bladed screwdriver and taped into place.N.B. if the shaft of the magnet tool is conductive and the magnet is plated or otherwise conductive, you should insulate the shaft or the magnet face with tape to avoid the risk of shorting the coin cell's +3V to nearby boards or parts.The other advantage of a magnet over a suction tool is the coin cell will jump to it as soon as its loose if its close enough. Unless the suction tool is *VERY* high volume, if the cell tilts as it comes out of its holder beyond the ability of the rubber cup to accommodate, it is likely to break the suction.

author: Kjelt
author_rank: Super Contributor
timestamp: August 01, 2017, 02:30:01 pm
content: That reminds me in the car toolbox there are these flexible (bendable) magnet pickup tools like these:https://www.tradetools.com/product-range/auto-and-mechanics-tools/automotive-specialty/force-flexible-magnet-pick-up-tool

author: Messtechniker
author_rank: Frequent Contributor
timestamp: August 02, 2017, 08:06:19 am
content: Quote from: Ian.M on August 01, 2017, 01:39:54 pmThe enclosed pics show the final embodiment of my BIOS batteryhandling tool for anyone to copy. The stick by the way is from a fireworks rocket.On New Years Day I go around and collect these sticks. They are quite handy for stirring paint among other things.I'm now off to replace some 25 BIOS batteries, because this time the clientcompany has decided not to discard their PCs after 5 years as in the past.Probably someone did the math.

author: Armadillo
author_rank: Super Contributor
timestamp: August 02, 2017, 08:17:57 am
content: Quote from: Messtechniker on August 01, 2017, 06:34:13 amThat is totally a different environment of removal !