I am considering attaching epoxy coated neodymium magnets to the tail caps of my non clicky lights and I am wondering how strong of a magnet do I need to make the flashlight stick no matter the position to metal surfaces (Car, fridge, tent etc.) but without turning myself into the x-men villain “magneto”
I have several 1xAA and 1x18650 flashlights that might get this mod.
I notice on ebay magnets with a N rating of N35, N42, N50, and N52, looking at slim round disks (1mm or less) what would be something good enough to do the job? Are the 18650’s or NiMh affected by magnetic fields? How about the Driver or led? Would this even be a good idea or upgrade or am I going to regret doing this? Hmmm……
I’ve not had any problems with the magnets affecting my lights or batteries.
As L4MA said, you will want a larger/thicker magnet, especially on the tail, if you want to ‘stick’ it on a vertical surface. Any coating between the magnet & surface you are ‘sticking’ it to will reduce the magnetic force also.
Go for the highest N rating you can find. The magnetic force will degrade rapidly with distance (extra geeky: almost inverse square when very close to one pole “almost a monopole” and moves towards inverse cube as you get further away and the distance from the object to both poles gets closer to equal).
Magnetic base lights are incredibly annoying when they are barely able to hold up their own weight. It will also help it stick to thinner metal better.
I just put a 1/4” dia. x 1/4” thick D44SH which has a pull force of about 3.35 lbs into my 4sevens Mini MLR2 and it would not hold the light to cast iron when assembled, without the battery in it. The thickness of the aluminum in this case is .1” so too thick.
If I tape the same magnet to the light with a piece of .050” (1.25mm) aluminum between it and the cast iron stove it does stick with a battery in it and it sticks good. Success!
The same approach with a 1/4” dia. x 1/16” thick D41SH, having a pull strength of 1.19 lbs, barely holds it to the cast iron pellet stove. It wants to slide vertically.
So it is clear that it will work best if the aluminum is very thin, ideally under 1mm and I would suggest getting a magnet with at least 3 lbs “case 1” pull force from K&J. Wide and thin seems to be the best way to achieve this. If you can fit it, the 1/2” dia. x 1/16” thick D81-N52 with 3.84 lbs pull force will work well as long as the aluminum in the light host is thin enough.
Use the largest diameter and thickest magnet you can fit in the host. These magnets can be soldered to and are electrically conductive so you can just put one right under the spring. Try to minimize heat input and use freeze spray after soldering. The “SH” designated magnets I have been buying are high temp rated so they will better maintain their strength after soldering. There’s a high temp 1/2” x 1/16” magnet, D81SH. It is N42 so not quite as strong but still has 3.1 lbs pull strength.
In regards to the magnet affecting the driver, Taskled says the following on their FAQ:
“The Flex drivers [with the exception of the Lflex] utilize a current regulated DC:DC switching regulator core. They all contain a shielded inductor that is the main power conversion device. The inductor should be kept away from nearby strong magnetic fields such as a nearby magnetically operated hall switch or reed switch. Maintain a 1” distance from the inductor to strong magnets.”
So I guess avoid putting a magnet directly near a buck driver with a switching regulator. I wouldn’t worry about components other than the driver being affected.
I kinda went a different direction… I ordered these 3/4” x 1/4” x 1/8” Blocks - Neodymium Rare Earth Magnets rated at 6lbs pull force. They hold very tight to the refrigerator. I have 2 BLF 348’s attached to my computer case, very secure. And they are removable.
And iffn you want to use the clip…just switch the magnet to the top of the clip. It ain’t going anywhere…it’s pretty strong.
Just added 7 small rpund magnets and 3 slightly bigger on the clip on my wifes red S2+ with 18350 tube
Used red shrinking stuff and it looks great, I stuck it on the fridge at eye level for het to find it.
I ended up switching the clip from the HC30 to my Skilhunt H15 NW which also has a magnet in the tailcap.
The original clip didn’t have room for the block magnet.
I use the H15 much more for close range work on car and under cabinet/sink/appliance/computer work.
And now it adjusts to cling in almost every conceivable situation. Very handy!
And I can clip it to my shirt/pocket by swiveling the magnet to the top of the clip.
This old thread being resurrected also got my attention since I’ve been wanting to add magnets to a few lights that didn’t have them. I’m ordering some from Banggood, N50 & N52 round (for tailcaps) and rectangular (for clips) 2mm and 3mm thick.
N52 seems about the strongest they have.
The tail magnet in my Olight S30 was 2.5mm thick, I can’t measure how thick the aluminum is in the base of the tail by I estimate between 1mm and 1.5mm
The magnet in that one shattered in 4 pieces when I tried to remove it, unfortunately I may need to contact Olight for a replacement because the magnet needs to have about a 7mm hole in the center.
