Problems with mode switching on Trustfire P7 flashlight?

[socalrunner]

Looking for a solution to a problem.. Bought a trustfire p7-a2 light last week and gave it to a friend. The light is very bright, we use for bike riding at night.. We are using protected 18650 cells but it seems there is a small gap when installing the batteries, compared to other p7 lights I personally have.. Whenever my friend hits a bump the light changes modes.. It happens very frequently..

I read in other posts that you can use rare earth magnets but special care is needed so it does not short the light out.. Not sure if the magnets are used on the positive or negative end of the cells.. Considering that the light is being used on a bike it is going to be jostled around, so is there a good solution?? This light is a single cell 18650 p7 flashlight..

Any and all help would be appreciated..

Thanks.. E.P.

 

[PhantomPhoton]

I'd avoid magnets in that situation. It all comes down to those cheap lights are just that, cheap. As for a solution, is there a spring that you can stretch? You've just got to hold those cells tighter in the tube so that the connection doesn't get broken while bumping. If there's too much extra space betwen the cell and the battery tube wrap the cells in paper to avoid "rattle." Tinfoil has also been strategically used before th help shim up some space, but just like the magnets do it with care... don't allow the positive side of a cell to touch the (negative current carrying) inner tube wall.

Did any of this make sense or help at all?

 

[socalrunner]

I will try stretching the spring.. If that does not work I will try making the cells fit a little tighter using the tinfoil method.. I did notice that there was a small amount of rattle in the light when we rode the other night.. He almost blinded a driver when we hit some rough roads and it went into strobe mode.. Nothing like a p7 strobe in your face when driving home..

 

[EngrPaul]

I assume a different cell was tried.

This light has a strong battery spring top and bottom. I don't think the battery loses contact. I would look at the switch.

Here's some troubleshooting ideas.

If you put some aluminum foil in the bottom of the tailcap to bypass the switch, does the problem go away?

If it does, it could be several things. A switch that's not designed to handle the vibration, a loose connection between the switch and tailcap or spring, or a rubber button that's tight up against the switch and puts the contacts in the switch near disconnect.

For the rubber boot, you could try removing the rubber button and operating the light without it. If it solves the problem, remove some height off the button nipple by turning the button inside out and carefully shaving with an exacto knife.

If it's a connection between the switch and the spring, you could try tightening the two crimp connections on the spring (See last picture posted below.) You could also expand the wing connections a little so it fits tighter in the tailcap.

If it's a switch that can't handle the vibration, it would be best to replace or bypass it. The least desirable option.

Here are some reference pictures for you or anyone trying to help you solve this issue:

 

[socalrunner]

3 different cells have been tried and they all have the same issue.. when the light is shaken it switches modes.. The batteries used have been Trustfire, Ultrafire and AW, all protected cells..

If I were to make this so it just works in 1 mode that would be fine, high mode is all he needs for riding at night..

Do I place the aluminum foil over the spring or place it at the end of the battery where I see the gap? Would using a properly sized rare earth magnet about the size of a dime be a better solution since there is no chance it will slip out of place at the negative end of the cell?