I’ve done the tail spring bypass with silicone wire on several lights but didn’t like the solder blob which dented a couple batteries. so I made a tiny copper disc from a real copper penny and soldered that on so it contacts the battery. is this a bad idea. btw I had blinking and mode switching with bumping so I put a better spring and it solved that problem—-also the noise on middle level is gone
Not a bad idea at all. You can even buy copper sheeting that would probably be easier to work with than cutting up pennies 
I had read that a larger contact point was beneficial so I sometimes make a small copper disc from sheet material and put that on top of the spring with the wire bypass soldered to the copper inside the spring. It looks neat, works fine, and helps to make a larger contact to the rear of the cell.
While I don’t condone destroying government property by using pennies, the idea is sound anyway (as long as the pennies are older and actually copper) It’s easier to use a sample pack of copper sheet material from a place like onlinemetals.com, like $10 for several 4x4 sheets of varying thicknesses.
thanks guys… I wasn’t sure about it and knew I needed to fix the flicker/mode switching —-it was driving me nuts —I had a cup of nasty pennies on the bench and found an old one and couldn’t resist
emarkd—- that’s exactly what mine looks like
its perfectly legal to use a penny to make a necklace or a charm… cant see why using it in a flashlight would be illegal.
“defacing” legal tender (what you call “money”) isnt what you think it is… so, my opinion is:
“If fixing a spring with a ONE CENT FIX is cheaper or better or even more convenient than buying a ”sheet” of whatever from whomever? feel free to do it…”
From where do i get my legal position? Personally, i consider the United States MINT to be a relevant source of information…
https://www.usmint.gov/consumer/?action=FAQ
and, heres a relevant quote…
QUOTE
Can I melt, drill holes through, or mutilate U.S. coins?
Maybe. It is a violation of 18 U.S.C. § 331 to alter a U.S. or foreign coin with the intent to defraud. The United States Mint cannot issue interpretations of criminal statutes such as this, which fall within the jurisdiction of the U.S. Department of Justice. Furthermore, 31 C.F.R. Part 82 states that no person shall export, melt or treat any 5-cent coin or one-cent coin of the United States. However, there are a few exceptions such as for novelty, amusement, educational, jewelry and similar purposes. Your business should consult with an attorney to ensure it does not run afoul of these laws before melting or mutilating U.S. coins.
ENDQUOTE
personally? i feel justified in my position that any sane legal opinion would agree that using a copper penny to fix a flashlight? Would fall under “amusement” and “educational” purposes.
The opposition to that train of thought is that if you were the only one that thought so, there wouldn’t be a problem. But if 10 million people hoard and/or destroy pennies, it’ll cost the US citizen a boatload to replace all those pennies. Fact is, they are Government property, used to barter for goods, “on loan” as it were. There will always be opposing opinions, but the age old “Give unto Caesar that which is Caesar’s” is difficult to dethrone.
Simple enough to use something else. Soldering the spring bypass solid then filing it smooth is probably the easiest and cheapest answer.
I imagine you’d spend a lot of time messing with shaping/cutting/smoothing a penny versus some fairly inexpensive 30guage copper sheet. I made a few quick and dirty pieces for my Maglite mod (positive and negative contacts). A few snips and a little dremel to round it up and it’s good to go.
On normal small springs I just flux the crap out of the top of the spring where the wire will be attached and then I spread the solder along just the top ring. That way there’s no bump to dent anything.
Rotary tool with a sanding drum smooths down solder very quickly too if you don’t get it perfect.
it didn’t take long at all. I cut it with emergency sheers then dremeledmeith a cutting disc followed by a sanding disk… I only used 1/4 of it for the plate— I got the idea from people here on BLF who were bulking up pills with copper…