Glueing battery connections

[Bill]

I said I would report back about my experiments with replacement CR2032 bios batteries in laptops. On my Acers and Lenovos these had spot-welded tags soldered to short wires to tiny plugs, the whole assembly being encased in heat shrunk sleeve.

The basic problem is that every connector seems slightly different and replacement battery units from ebay that I bought had the wrong connectors. It seemed sensible to try to connect up cells directly to the old connectors rather than cut and join the wires.

The space in the laptops is extremely limited and it turned out that 2 of the 3 laptops tried had the thinner 2025 batteries.

I bought a syringe of carbon based conductive glue from a UK supplier and silver based glue from China. I found it quite easy to prise off the small, thin spot-welded tags from the old batteries, so I used these, pre-soldered to the connector wires, for the attempts to glue connectors to the batteries.

The first problem was that both syringes took quite a bit of thumb pressure before a big glob of glue suddenly appeared. I found smoothing this out to be difficult.

The carbon based glue turned out to be much better than the silver, but both types had a sort of lumpy, almost crystalline consistency and neither flowed well. Both are quite slow drying, so I left them both for two days.

The heat shrink sleeving that I have is quite a tight fit over the batteries, and it is touch and go whether the sleeving can be pushed on without disturbing the glue joint.

I ended up with a successful carbon glue attached battery, but couldn't get a strong enough bond with the silver.

I also bought some vertically pcb mounting tagged CR 2025 batteries and soldered up one of these. I have to say that the advice here from everyone was right - this is better than glued connections. The only issue with this is with space. I felt it prudent to sleeve the soldered connections individually and this sleeving coupled with the main battery sleeve added to the bulk.

The machines are all back together and all working, but all turned out slightly thicker than the originals and succumbed to pressure.

The one thing that came out of this was that I discovered the existence of IPA dosed pre-operation swabs, which seem ideal for cleaning delicate electronics. Asking in local chemists for these drew a blank, but they are on ebay, seemingly aimed at tattoo artists, so I've invested in a small quantity .

[Brian Reay]

You can spot weld tags to batteries with a couple of thick wires and a car battery. Have a look on Youtube.

If you only do a few, then it isn't worth making a proper spot welder.

[Brian Gaff]

So it seems incredible to me that they would design a machine with a non replaceable battery like this, and even then not sell a solder replacement either leaving people to have to make do and mend. I seem to recall we had similar issue with the old Sinclair Microvision tvs when Polaroid discontinued the special batteries. Brian

[Brian Gaff]

If there is sufficient thickness in the plastic case parts, then one can remove some plastic internally where the tags are to stop straining the case. I remember doing this many years ago with a rechargable shaver, I used an old soldering iron bit to melt a dent into the plastic in the offending spot! Ponged a bit when being done though. Brian

[Bill]

In message , Brian Gaff writes

Brian, the design concept for these batteries is that it should be easy to simply remove the keyboard, unplug the old battery, plug in the replacement, replace the keyboard and that's it. These machines are moderately old but, for example, Amazon do sell replacement batteries, at least for the Lenovo's. I looked up the ones for the two machines I have. One is listed as "by unknown" and has a vague description, the other appears to be from someone in Germany who also trades on ebay. The description of the battery does not match the picture. Also the battery is listed as a 2032, whereas the one in the machine, which appeared original, was a 2025.

I did buy one from ebay, but the connector was wrong. The sleeved solder joints swapping the connectors over were really too big for the free space in these small laptops.

The batteries are between the keyboard and the works of the machine. No plastic there to scoop out!

[Ian Jackson]

In message , Brian Reay writes

With a good hot iron, and if you're very quick, you can solder to these batteries. But I did say 'hot', and I did say 'quick'.

[Rob Morley]

People build their own battery packs from 18650 cells by spot-welding them together using high-tech equipment like old microwave transformers. I wonder how hot you can get a cell, and for how long, before significant damage occurs.

[therustyone]

I got a battery for an old IBM Thinkpad circa 2005, from eBay. The connector was correct and fitted OK.

1 item sold by componentwarehouse 2 Pin IBM Lenovo Thinkpad X300 X400 Z60 Z60M Z60T Z61 Z61E BIOS CMOS Battery ( 122666867916 )

ITEM PRICE: £2.59

[The Natural Philosopher]

Far out.

So what?