ALL SOLD: Magnets (6mm x 1.5mm) to convert flat-top batteries into button-tops

Buy / Sell Want to Sell
21

Too much effort and it doesn’t stop the magnets from moving around when the flashlight is bumped.

I’m going to try JB Weld, after my family goes to sleep tonight. (I find that is the best time to tinker around with my flashlights. :wink: )

Reference links:
Post No. 14
Post No. 5

I just happen to have on hand some JB Weld. Otherwise, I would have tried some Super Glue gel or regular 2-part epoxy glue.

22

PayPal sent

Thanks!
Phil

23

First, I cleaned the battery tops and the magnets with isopropyl (rubbing) alcohol, to clean them.

After drying, I placed the 6mm x 1.5mm magnets on the battery positive terminal of all four batteries.

Then, I carefully squeezed Super Glue Gel around the outside edge of two of the batteries, using a toothpick to smooth out any blobs of glue. Here’s what it looked like after it was done:

Next, I mixed the 2-part JB Weld epoxy glue. Using a toothpick, I tried to carefully swab the glue around the two remaining magnets. I found this very difficult to do. Because there are iron particles in the JB Weld, the glue tends to seek the strongest magnetic pole, which is the exposed face of magnet. Here’s the results of that effort:

It was MUCH EASIER using the Super Glue Gel than the JB Weld.

However, the proof is in the pudding. We’ll have to see which set performs better/lasts longer.

I’ll test them out later, after they have had time to cure.

24

1dash1, if you were going to put that much effort into making a positive terminal on your cell, you could have just used a little piece of copper soldered on. I’ve done it a couple times with regular solder. You just pre-tin both the end of the cell and the piece of copper, then a little bit of flux and some heat. It might be easier with solder paste, though. Add just enough heat to flow the solder, then done. I used solid #4 copper wire for the nubs. Just cut off a one or two millimeter thick piece and sand it both sides flat. Copper is a much better conductor than the magnets can ever be.

Having said all that, I prefer to use magnets. To me, the reason for using magnets is that they aren’t permanently attached to the cell. They are very strong magnets and they won’t easily move. If I ever needed the added assurance, I’d probably use a washer, as has been suggested.

25

Reasons why I glued the magnets on:

  • I’m out of flux at this time.
  • It wasn’t that difficult. The Super Glue Gel took about a minute for both cells. The JB Weld took over five minutes and most of that time was clean up/trimming of excess material. (Taking the photos, downloading them to my PC, trimming them to size, and uploading them to a photo website was much more time consuming than the gluing operations!)
  • Like you said, the magnets stick pretty good. The glue is just an additional measure.
  • If I want the flattops back, the glue is removable.

But the main reason is “because it was there”. :wink:

I remembered coming across the JB Weld when I rummaged through one of my desk drawers a day or two beforehand. I had read about others doing it. So, what the hey! Give it a try. :party:

26

+1 on super-gluing the magnets on. Super EZ no muss no fuss. Where needed, mine have been in place for at least 2 years. Don't appear to be going anywhere...

27

Yeah, but my point was that copper conducts better if you’re going with “permanent” attachment, so the only reason I use magnets is because they don’t require any type of glue. To me, gluing down a magnet as your positive contact on a cell is getting the worst of both worlds! It would even be better to super-glue copper contacts, as long as you’re only gluing around the edge. If you’re worried about good contact, you can use a magnet or a spring clamp to hold it in place while you dab a few drops of super glue around the outside edge.

28

Dash I got them the other day.That was fast.I have them stuck to the frig still in the envelope under pictures of grand kids. :smiley: Thanks Again

29

And many thanks for them :slight_smile:

Super-glue holds best in least quantities, and doesn’t bond nearly as well around something as it does between things. It might do well enough with these though. I am going to use a toothpick or pin to put a trace of superglue at the face-edge of the magnet just before sticking it on. It will reduce contact area slightly but I don’t think enough to matter, and if I want it off it should pry off from the edge opposite the glue, or acetone will release it. More than a tiny trace of superglue could cause a considerable loss of contact, and any epoxy would be rather permanent. The two most common failures of superglue are using too much and re-gluing: it doesn’t stick to cured superglue well so if you need to re-glue clean all the old glue off first. It’s strongest bond is when it’s one molecule thick- more is less with superglue. It also produces cyanide gas when burned raw or cured adding to the mess should a cell go into thermal runaway which is another reason to use it minimally.

Cute little buggers these magnets are!
Phil

30

> little

Just for the repetition value, remember these very small strong magnets are a big hazard
https://www.google.com/search?q=magnets+child+baby+intestine
where young children are around, young enough they put things in their mouths.
I figure y’all are well aware of this, but I still come across people who don’t know about the problem. And those tiny magnets are showing up in consumer goods for holding flaps down on boxes, etc.

31

Thanks, Hank!

Another bit of common sense, glue should only be used around the outside perimeter of the magnet not between the magnet and the battery terminal plate.

32

I use hot melt glue around the outside perimeter of the magnet after cleaning the magnet and the battery.

33

For UK guys - I’ve ordered 10 6mmx1mm magnets which’ll come this Weds/Thursday. I’m only going to need 4 so the other 6 will go to waste. If anyone in the UK wants them PM me and I’ll 1st class post them to you for free.