FENIX TK60 BATTERY / TAIL CAP SPRING PROBLEM

Hi guys,

Not sure where best to post this but I assume in the LED flashlight rather than the battery forum is best.

I recently bought a Fenix TK60 and to go with it a set of Maha Powerex 11000mAh rechargeable D cells.

I put the batteries in for the first time last night to try the light out and when I was finished I took them back out again and noticed that the battery at the tail cap end of the torch had been dented and scratched by the spring in the tail cap.

Obviously this is concerning to see as I assume damage to a battery is never a good thing and I assume the damage will continue to get worse, either by the constant spring pressure when the tail cap is screwed down or by the rotation of the spring when the tail cap is removed to take the batteries out to recharge them.

Looking for your thoughts, advice etc re this.

I have the same, with my TK70. It still works, so I don't think it is a big problem.
I keep chancing my batteries, so they are all a bit dented.

try taking the spring out of the tail cap, put it in a vice and sqeeze down on it so the spring isnt so strong. it should help.

liquidwater said:

try taking the spring out of the tail cap, put it in a vice and sqeeze down on it so the spring isnt so strong. it should help.

Click to expand...

Possibly stupid question but here goes - how do you get the spring out? Is it just a press fit that is wedged into the tail cap? I gave it a bit of pull and a twist last night but the spring didn't seem to move.

Cheers!

To reduce the galling somewhat, take the sharp edge away from the spring end, (the cut-off point where they have closed the coil end).
I did this on my TK70 tail spring. I used a small EZE-LAP diamond sharpener, it only takes 30 seconds.
Don't go mad and remove the gold plating along the contact surface though, only the very sharp tip of the wire needs fettling.

I would caution the idea of trying to reduce the spring tension. But if you decide to, the light may change modes easily if it is bumped or knocked, because of the electrical circuit momentarily disengaging.

NiMH are usually built with a metal plate at the bottom... so that's not your battery being hurt too badly yet.

I just checked the spring in my TF-60. Holy smokes, thats one tough spring!
I noticed that the spring is engages at the very first thread and there are still
about 3/8" of threads left to fully screw on the cap. That much compression
seems excessive to me.

On the flip side, I'm thinking that with 4 D batteries, a heavy spring might
be required to stand up to the enertial weight if the flashlight were dropped
or bumped on the tailcap. I have had other 4D lights that would eventually
cave in the buttons and now I'm thinking its was because the spring was
not strong enough to keep the batteries from slamming the head in case of
a drop.

I noticed the same thing on the TK70. I smoothed the end of the spring with a Dremel grinder fitted with a diamond wheel. I also put a dab of lubricant on the spring. No problems so far. If you inspect your flashlights you'll find that many springs are ground down at the factory, or have a bend to lessen the effect of the rough spring on the battery.