A New Way To Deal With Flat Top Li-ion Batteries !

If you have been using Li-ion batteries long enough more than likely you've ran across batteries that a low profile flat top that won't make a connection with a second battery when both are placed in a laser host....





In the past the fix has been to buy small thin neo magnets and place them on one of the batteries in-between the two batteries that won't make a connection, Well I have what I think is a better solution to the problem !

Simply flow a little bit of solder on the surface of the positive pole on each battery and problem solved for good !




No more magnets to buy and get stuck to everything but the battery, No muss no fuss !

BUT there is a catch ! To do this correctly requires a very powerful soldering gun ! I'm talking at minimum a 260 watt Weller soldering gun !



The reason for this is you want the least amount of heat being soaked into the battery or you could damage the cell, The trick to doing this correctly is a ton of constant heat focused to the surface to where the solder will flow for just a few second and done and gone !

It's just that simple and you will never have to mess around with that battery again !

Now if your at all concerned with the electrical contact surface of the slightly rounded surface of the solder and would like a more broad contact surface simple drag the solider surface across a sheet of sandpaper a few time and your done !


Now let the barrage of criticism begin ! lol

This should be entertaining op:

And the criticism will be well deserved. :tsk::tsk:

WizardG said:

And the criticism will be well deserved. :tsk::tsk:

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How so ? Are you suggesting there is somehow something inherently wrong with this ? If so by all means enlighten me or share your better way.....

You don't need to heat up the whole battery to screw it up.

You're talking about heating a very small contact plate to apply the solder. That contact plate is held in place by crimped in polyethylene (or PTFE) seals which will be softened and will subsequently leak. If the seals are polyethylene the cell might even short out. Messy business with Li ion cells.

I used to do the same thing in my younger days. I learned the hard way. I think you do a disservice to this community by offering up a 'suggestion' like this on an open forum where many noobs come to learn and might think yours is a reasonable idea.

No ... really bad idea. Use solder tabs to solder cells. The solder can leak around the sides and short the battery if you don't know what you're doing and solder the battery contacts directly.

I'm with Accutronitis on this one. I've been doing this on some of my cells for a while.

I don't baby my lithium cells. I see no reason to do so, seeing as they're so cheap and have limited shelf life anyway. I understand others do, but that isn't the only "correct" answer.

Cyparagon said:

I'm with Accutronitis on this one. I've been doing this on some of my cells for a while.

I don't baby my lithium cells. I see no reason to do so, seeing as they're so cheap and have limited shelf life anyway. I understand others do, but that isn't the only "correct" answer.

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Fine if you know how to solder half-way decently. But someones bound to see this that can barely solder, and think "Oh yeah! Great idea!" then burn their house down once they short out the cell by using half a spool of solder on the contact.

Yea I also found out the hard way and killed a battery doing this. Well, I'm actually still not sure if it was directly from soldering. It was fine after doing so but after letting it sit (probably over a couple days) I come back to see it at 0.1v and some kinda brown crap on the platform I soldered on.

All this time I thought the tops were stainless steel and unsolderable. Although I agree, Heat could be a problem for some.

Wait, you can actually solder to the top of these batteries? I always thought they were steel, and you can't solder to that typically. They're magnetic, so I'm not sure what other metals they could be.

I always solder a lump on all my flat top batteries. I'm careful but it works.

diachi said:

Fine if you know how to solder half-way decently. But someones bound to see this that can barely solder, and think "Oh yeah! Great idea!" then burn their house down once they short out the cell by using half a spool of solder on the contact.

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A few threads on this and quite a few good builder's recommended this, instead of magnets that might wander off that some have found like "RedC" who comes to mind use a O-ring to hold the magnet from sliding.
Actually I thought Accu was going to get blasted for bringing up old news..

diachi, is right on though as yes iv'e tipped off a few battery's with solder but my hands aren't to steady and my solder skills are horrible. Its wasn't a comfy feeling heating and re heating that battery top till I got it kinda right

That O'ring idea is something I didn't see, good idea, I've been worried the magnet could side over and short to the case.

I remember when one of our members "Larry DFW" was selling panasonic batteries here; he would buy the flat top cells, and if the buyer wanted button tops, he would solder a button on them for no extra charge.
I don't recall anyone ever having trouble with any of his work over the years.

I can see the possibility of damaging a battery with too much heat for too long of a time, but if you're a competent solderer and treat it like a diode, where you want to get in and out as fast as possible, this should be a good alternative to magnets.
As always, when attempting something like this, it's at your own risk. I've been tempted to try this on some of batteries, but so far have stuck with magnets.

Hi .
Did it countless number of times works great don't need much heat .
My house is still here .. no problem with solder blobs on the cells

Rich

GSS said:

A few threads on this and quite a few good builder's recommended this, instead of magnets that might wander off that some have found like "RedC" who comes to mind use a O-ring to hold the magnet from sliding.
Actually I thought Accu was going to get blasted for bringing up old news..

diachi, is right on though as yes iv'e tipped off a few battery's with solder but my hands aren't to steady and my solder skills are horrible. Its wasn't a comfy feeling heating and re heating that battery top till I got it kinda right

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Actually that's a good idea, the O-ring.:thanks: I use a few magnets with my silver series made by podo, thing is it fits the batteries perfectly without the extension tube but needs the batteries when the tube is used. Even when the batteries have bumps. I haven't had problems with the magnets sliding around in that laser but then again if the spring is weak on your laser, it could be a problem.