My 18650 batteries are about 1/8 (3mm) too short for my light.

What to do?

The batteries that come with the light are perfect, but all the panasonic 18650s I have purchased are about 1/8 (3mm) too short.

I was thinking of using aluminum foil.

I dont really want to add solder but will as a last resort.

Any ideas?

Some people use small neodymium magnets.
You might also be able to stretch the tail spring.

What Halo said, neodymium magnets, if you don't want to solder. Depending on which end on the battery you should put them depends on the which light it is. What light is it? In my experience, the only light I have that is too short for unprotected cells is the Noctigon M43. It works, but barely, and only if I make a solder button on the + end.

Dab a little HGH on them. They’ll get bigger

You can use magnets or take some copper braid and fold it and solder it to the driver or switch spring. I would do the latter. Bypass those springs while you are at it. You could also take one of the brass caps that come on some of the springs, cut it to the length you need, and solder it to the switch or driver spring.

The obvious questions:

Have you tried the button tops and have you tried protected button tops?

Some lights are designed to only accept protected cells.

Where do you get them and what size for the 18650s?

Its a diving light.
Cheap but solid and very bright.

I am using button tops.
Standard Panasonic batteries but the light comes with some generic brand battery that is longer.

I just checked their website and their batteries are protected.
The lights are only $50 so I am going to stick with my Panasonic standard batteries.

I have one of their video lights and they work in them for some reason.

HKJ says Test / Review: NCR18650A protected (Green) that the panny ncr18650 protected he tested were 69.7 long how long are your “good” ones?

My batteries are not protected.
I have said that already.

Well, all you need to know is written in the first answer.

If you would measure your batteries, you could find out, if they are maybe fakes?

Not home ATM but they are legit as far as all the reviews on Amazon (and weights) go.

Protected batteries are longer or the same length?

Longer, because of the little protection-circuit.
They are 2-3mm longer.

You can use a magnet or just a little piece of metal - just make sure it doesn’t short out the battery!

ANd maybe you could contact the producer, what he sais about that.

If you can solder but just aren’t comfortable soldering to the battery, I suggest you replace the spring with a longer one. It makes it easier to swap batteries than a small magnet would permit. (IMO)

Protected batteries will be longer.
Is my battery protected?

Protection always adds length for the protection circuit.

Yep they must be closed today.
Usually they are good with CS.

Not sure I can access it as its a long way down and a diving light so pretty well sealed.

The magnets might be the best bet then.

Anyone have a link or know which ones to buy off Amazon?

And do you just throw it down the barrel before you put the battery in?