Favorite way to "fix" U2 head spring?

My 18650 cells don't have enough button on the top to make contact with the spring at the head end of my U2. What's the best way to fix this?

- Solder blob on the top of the 18650 cell?
- Small neodymium magnet stuck to the top of the 18650 cell?
- Gently stretch the spring at the head? (there isn't much there to start with)
- Wedge a larger spring in/on/around the existing spring?

I'm looking for suggestions as to the best way to fix this. I've got the following considerations in mind:

- Reversibility of any modifications made to light or to cells
- Risk of damage to light or cells
- Risk of dead short
- Overall reliability
- Best electrical conductivity
- Ease of implementation
- Ease of daily use

Sorry if I'm looking too deeply into this...

2 and/or 3

I stretched my head spring. Hadn't thought about it until I saw this thread.

Small neodymium magnet stuck to the top of the 18650 cell.

Michael

Incidentally, after reading Newbie's li-ion safety sticky thread, I'm having second thoughts about the magnet fix. Wouldn't want the magnet shifting and

I ended up going with the spring stretch method. I was concerned there wasn't enough of a spring there to get a good contact (this thing pulls 1.5A on high). So far, it seems to work fine with nary a flicker.

I agree with the comments on Li safety. I wouldn't want ANYTHING that might shift unexpectedly and cause a dead short. I'm pretty sure that a fully charged 18650 cell isn't something to fool around with.

On a side note, I'm liking my U2 more each day. We got off to a shaky start (donuts, bad switches, and off tints), but the more I use this light, the more I appreciate what it can do.

Ty_Bower said:

I agree with the comments on Li safety. I wouldn't want ANYTHING that might shift unexpectedly and cause a dead short. I'm pretty sure that a fully charged 18650 cell isn't something to fool around with.

On a side note, I'm liking my U2 more each day. We got off to a shaky start (donuts, bad switches, and off tints), but the more I use this light, the more I appreciate what it can do.

Click to expand...

Ditto, on both comments.