STRONG magnets and Li-Ion cells

I have a full sized pickup, and a squat / narrow 10' aluminum Jon boat that I cannot see when I am towing it, no biggie going forward. Backing up is a different story. The trailer is way too small to install those PVC vertical tow light kits (trust me here) so I found a solution that works wonders at least during the daylight hours.

I got a pair of 4 foot STRONG magnetic fluorescent posts that I can stick on the trailer tongue and easily see how much my trailer is turning when backing up, but at night I have a problem seeing them.

So... I have an Ultrafire single cell UV flashlight that I can use to light up (boy it REALLY lights them up) the fluorescent posts. I want to epoxy a STRONG neodymium magnet to the tube of the light and attach it to my truck bed when backing up. This way I could see the darn posts at night, but since the battery casing is steel I'm wondering if a strong magnet will have any negative effect on the cell installed in the light when using or for storing the light?

Shouldn't be an issue. Some manufacturers like Armytek even offer tailcaps with a magnet already installed.

I asked a similar question here
My conclusion is there is Zero effect on any flashlight Battery type, Alkaline, NiMh, LiIon, from strong neodymium magnets.

One idea you might want to test before using epoxy, is to use some tape to wrap around the light, with the magnet under the tape. That will let you experiment with how many magnets, and their positioning, works for the weight of your light.

Another idea is to get a group of large inexpensive rectangular magnets, and let them hold themselves to the truck in a way that allows you to trap, or sandwich your light. So that you can remove the light and leave the magnets behind.

I sometimes don't like when my flashlight has a glued on magnet, because it grabs other things in my pocket, or sticks to stuff I don't want it to. But for your UV light, I think just taping some magnets to the body of the light will work fine. And no, it won't hurt your batteries.

Let us know what magnetic setup works for you

these are some of the ways I use magnets with my AAA lights.
Notice the large one on the right also acts like a shelf. You could stack a few of those and create a shelf to hold your flashlight to your truck. I suggest covering the magnet shelf stack you build, with a layer of tape before you stick it to your Truck, so it does not scratch your paint


the magnet on the left is neodymium, it is very strong and would work well taped to the body of a light. (stacking adds magnetic power)


I carry AAA lights as EDC. I leave magnets in various places where I occasionally adhere the light, and then remove it again.

car visor


in this stack, the black magnet is the weakest. I like that I can pull it off the metal body inside my camper, more easily than neodymium. I can easily move the magnet stack to a different spot along that metal trim piece.


on my car dash, thats a magnetic cell phone holder, very inexensive on ebay. It has 4 neodymium magnets under the rubber cover.