Where to buy reasonably priced magnetic spacers to convert 18650 flat tops?

Where do I find reasonably priced magnetic spacers to convert 18650 flat tops to button tops?

I looked on fleabay but I don't want to pay $1 per spacer. I mean, I can afford it but the cost seems excessive and I despise rewarding greed in any shape or form.

I don't eat $12 hamburgers or drink $15 cocktails. I quit rewarding greed after greedy mortgage brokers crippled our economy.

(Okay, let me just climb down off this soap box).

Thank you.

One of the reasons you don't find an abundance of these, is that they're generally discouraged, and I don't think many serious vendors would offer them. Keep in mind that you don't need contact between the top and bottom of a battery to make a (dangerous) short, but the top and any other metal part of the battery will do. A paperclip slid in at the top could easily get the job done.
To make matters far worse though, the shell of a flashlight is often connected to the bottom of the battery. Any contact between the top and the shell, would then cause a short.
Then there's the risk of physical damage, such as breaking free a spring, which in turn could short out things, and so on.

Speaking of generally discouraged, I'd like to discourage it as well, but you probably already noticed that.

There are good high-quality button tops out there (for a good price), both protected and unprotected.

terjee said:

One of the reasons you don't find an abundance of these, is that they're generally discouraged, and I don't think many serious vendors would offer them. Keep in mind that you don't need contact between the top and bottom of a battery to make a (dangerous) short, but the top and any other metal part of the battery will do. A paperclip slid in at the top could easily get the job done.
To make matters far worse though, the shell of a flashlight is often connected to the bottom of the battery. Any contact between the top and the shell, would then cause a short.
Then there's the risk of physical damage, such as breaking free a spring, which in turn could short out things, and so on.

Speaking of generally discouraged, I'd like to discourage it as well, but you probably already noticed that.

There are good high-quality button tops out there (for a good price), both protected and unprotected.

Click to expand...

I could not have said it better.

+1

terjee said:

One of the reasons you don't find an abundance of these, is that they're generally discouraged, and I don't think many serious vendors would offer them. Keep in mind that you don't need contact between the top and bottom of a battery to make a (dangerous) short, but the top and any other metal part of the battery will do. A paperclip slid in at the top could easily get the job done.
To make matters far worse though, the shell of a flashlight is often connected to the bottom of the battery. Any contact between the top and the shell, would then cause a short.
Then there's the risk of physical damage, such as breaking free a spring, which in turn could short out things, and so on.

Speaking of generally discouraged, I'd like to discourage it as well, but you probably already noticed that.

There are good high-quality button tops out there (for a good price), both protected and unprotected.

Click to expand...

So I should just toss the flat tops? Why do they make them to begin with?

mickeyfinn said:

So I should just toss the flat tops? Why do they make them to begin with?

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In a way, flat tops are the originals. These batteries are really industry batteries, used in power tools, laptops, electrics cars and the like. Button top is more of an add-on, with some lights using it for reverse polarity protection.

If they're of good quality, I'd hang on to them for any future use. Just like some lights require button tops, others require flat tops. Some accept both. Even if they don't fit your current light, they might fit another light in the future.

Also, with Nitecore F1, you could use them as a power bank if you'd like. It's a really neat little thing, that'll let you use USB to charge 18650s, and also use 18650s to charge USB-devices. Cheap too, around $8 or so I think. If you want to use them in a light, there's Convoy S2+ for example, which is a decent light that can be found in a lot of different configurations, often around $10. Makes a nice backup light.

In most cases, flat tops are unprotected cells, while button tops are protected. The advantage of protected cells is the printed circuit board (PCB). Conversely, the disadvantage of protected cells is also the printed circuit board. In other words, the PCB prevents over charging and over-discharging, making the use of protected cells essentially fool proof. On the other hand, the PCB becomes another potential source of electronic failure. Unprotected cells won't fail suddenly leaving you in the dark, but they require a thoughtful user who can monitor voltage and manually avoid over discharging. Most flashaholics stock both varieties for different applications.

My advice is to keep your flat top cells, but not to use magnets or spacers to convert them to button tops. The danger of a short circuit is real. Good cells of both varieties are inexpensive enough that it should not be an issue.

Hi terjee,
I have some 18500's I use in my Surefire 9P, G3 & my Seraph-9. Because they are flat tops, I use a tiny neodymium magnet, surrounded by three "gaskets" from IMR, and then where the positive end of the bottom and negative end of the top Cell are connected by the magnet I wrap a layer of electrical tape around it(thus keeping the magnet from physically shorting out against the body). What is your opinion of their safety?
I have been using the setup for a couple of years without any problem.

Crazyeddiethefirst said:

I have some 18500's I use in my Surefire 9P, G3 & my Seraph-9. Because they are flat tops, I use a tiny neodymium magnet, surrounded by three "gaskets" from IMR, and then where the positive end of the bottom and negative end of the top Cell are connected by the magnet I wrap a layer of electrical tape around it(thus keeping the magnet from physically shorting out against the body). What is your opinion of their safety?

Click to expand...

It's hard to comment based on the description alone, without having seen it. It sounds like it's not ideal, but far from horrible as well.

It really depends on how reliable it is, how fast/easily it can fail, and what can go wrong when it does fail (running on the assumption that anything and everything fails eventually). I have to admit it sounds like an upgrade from just sticking a magnet on top, but personally I'd be wondering about things like the tape failing if the light is accidentally left in the sun (heating the glue of the tape) and so on.

One of the things I can't really see, is whether the magnet is small enough that it could get in and short out the battery, or large enough that it could connect the battery to the chassis, if the arrangement starts to fail.

It's probably not something I'd do myself, but I tend to be a bit on the cautious side with LiIons. It does sound better than some other solutions I've seen.

I agree with @terjee, but like @Crazyeddiethefirst, I wound up with some flat tops I could not use due to a shipping error. Those of you who frequent the other forum know what went on about a year ago. I found some rare earth round magnets that were designed to do just this thing, on either Banggood or Gearbest. I also bought some of the gaskets Crazyeddie is talking about from IMRBatteries. They look a lot like the reinforcement rings we used to use for notebook paper in ring binders, but thicker, and the hole is smaller. They are at least twice as thick as the reinforcement rings. I used a single gasket on each cell, but I suppose you could stack two if you wanted. I tested the magnet after I got it set up. I whacked it as hard as I could against the heel of my hand, and nothing moved. I suppose if one wanted to be really sure a drop of two of Elmer's on top of the gasket around the magnet would help hold things in place. By putting it there, it should not wick underneath the magnet and cut down on connectivity.

I always use 100 watt soldering Iron to convert cells in to buttontops it works great

Fastest method - Drop of solder using 100W soldering iron. Second - small piece of copper soldered with 100W soldering iron. Third - copper wire bent like spiral soldered with 100W soldering iron.

fonfan said:

Fastest method - Drop of solder using 100W soldering iron. Second - small piece of copper soldered with 100W soldering iron. Third - copper wire bent like spiral soldered with 100W soldering iron.

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Why 100W soldering iron?

Why not 80W, 70W or 60W soldering iron?

Most of the people think that Heating up a Cell is very Dangerous So if you take soldering Iron of 80 or 100 watt You put in a lot of heat but you will do this In A Very short Time Five or six Seconds
this Short amount of time is Enough to apply the tin
After the soldering cool the cell on a wett sponge

mickeyfinn said:

Why 100W soldering iron?

Why not 80W, 70W or 60W soldering iron?

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I'll try and explain.
Normally the area you need to heat when soldering electronics is much smaller than the top of an 18650 battery. That large area is a heat sink. It will pull the heat out of the iron much faster than a small area. A higher wattage iron will lose heat at a slower rate and also it will recover from the heat loss much faster. It will give you a much better chance of satisfactory results. Based on your question I am assuming your soldering experience is somewhat limited. I strongly suggest that you practice first on an aluminum can or similar then work your way up to a battery. Soldering is a good skill but it's not something you were born knowing how to do, it takes practice.

It is possibly to solder the tops on, but I wouldn't recommend it for anyone that isn't a professional or experienced amateur. It's back to the whole "yeah, it's possible, but also dangerous"-side of things.
To do it somewhat safely, you'd need to inspect the soldering to make sure it's properly bonded, you'd need to make sure it won't be too soft, won't chip, and so on.

And you'd need a good feel for temperature movement, to heat the solder and pad high enough to bond, without heating the battery itself too much. That's why you'd need 100W.

I'd actually rate the using of well protected magnets as mentioned, as less dangerous, for anyone not experienced.

terjee said:

It's hard to comment based on the description alone, without having seen it. It sounds like it's not ideal, but far from horrible as well.

It really depends on how reliable it is, how fast/easily it can fail, and what can go wrong when it does fail (running on the assumption that anything and everything fails eventually). I have to admit it sounds like an upgrade from just sticking a magnet on top, but personally I'd be wondering about things like the tape failing if the light is accidentally left in the sun (heating the glue of the tape) and so on.

One of the things I can't really see, is whether the magnet is small enough that it could get in and short out the battery, or large enough that it could connect the battery to the chassis, if the arrangement starts to fail.

It's probably not something I'd do myself, but I tend to be a bit on the cautious side with LiIons. It does sound better than some other solutions I've seen.

Click to expand...

Thanks for your opinion. I am using incredibly small but powerful neodymium magnets that are not large enough to touch the flat top cap and the body at the same time. The electrical tape and IMR Washers(I use two so the amount of any movement is limited) are merely additional safeguards. I should point out that any of the new 18500 cells I buy will be buttontop. After reading this thread, as well as an unfortunate experience very recently(see my thread "Dealing with Lithium-ion batteries while impaired"), I have opted to no longer use my 4 18500 flat tops in tandem. They will now be relegated to my Jetbeams with an adapter(similar to the Sunwayman V11r), that can use the flat top 18500's. Once they have reached their end of usefulness they will be recycled and only replaced with button top only. Thanks to all who contributed to this thread, both asking questions and giving answers. Raising awareness of the potential to cause a short when using Lithium-ion batteries can only be beneficial when shared. I had come to believe using magnets was an acceptable practice, and even though I took precautions, I feel it best for me personally to stop doing so. Balancing the cost of a short, possible burns, starting a fire, hazardous gas release, etc. Vs $10 for a couple new cells, it is an easy choice for me. I realize others may make a different choice, but having heard from various voices of experience on the forum, the choice is easy! Thanks CPF!

Crazyeddiethefirst said:

.... I am using incredibly small but powerful neodymium magnets that are not large enough to touch the flat top cap and the body at the same time....

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The magnet doesn't even necessarily have to reach the side if the tube to cause a short, since (for most common cells) the can itself is usually negative too (!) ... oo:

Crazyeddiethefirst said:

Thanks to all who contributed to this thread, both asking questions and giving answers. Raising awareness of the potential to cause a short when using Lithium-ion batteries can only be beneficial when shared. I had come to believe using magnets was an acceptable practice, and even though I took precautions, I feel it best for me personally to stop doing so....

Click to expand...

I, too, no longer use magnets :duck:

easy. just buy a spot welder. get nipples from fasttech aliexpress etc

Who here has used a magnet to convert an 18650 flat top and actually suffered a short or encountered some other problem?

Is it safer to use a magnet this way in an anodized flashlight?

mickeyfinn said:

Who here has used a magnet to convert an 18650 flat top and actually suffered a short or encountered some other problem?

Is it safe to use a magnet this way in an anodized flashlight?

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Things can happen. I don't use magnets, or solder. Cells are cheap and many quality vendors sell great cells with button tops for not a lot of money, so it's prudent to just go that route unless you're down to your last pennies and just have to forego paying the electric bill, or mortgage, in order to jerry-rig your flat tops, that just don't work in a particular light.

With lithium ion cells, which pack a lot of energy in a sealed aluminum tube, you probably just want to err on the side of caution, but many people successfully use magnets.

Chris