6 watt laser build, host tail cap can't handle the current

My idea is to keep the spring as it is, but just solder a short length of copper from one end to the other - this keeps the mechanical action of the spring to some degree yet negates the problem of the poor electrical conductivity of the steel. Surely it is a hack, but if it just the last little bit you need it could do the job.

I've found that you can actually solder onto most springs used in flashlight housings and such. This would probably not be the case if they were pure steel, i suppose they are nickel plated or something to help with electrical contact, which also helps soldering onto them greatly.

As for the magnet switch idea: It's not a new idea at all, i think there are some products on the market that use this approach already (not sure for lasers, but for things like diving lights and such). Upside in that case you can have a hermetically sealed case that does not rely on a floppy piece of rubber to prevent water ingress, a serious problem once you get to several bars of pressure.

These are doubles that you can cut apart at the bottom, beryllium copper.
You can reshape the spring some or use a circle of plastic cut from a sandwich meat box or other household item to insulate underneath.


https://www.ebay.com/p/2-Sets-Dual-...d=263248637663&_trksid=p2047675.c100005.m2219


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If you are going to build a lot you can make your own springs, piano wire for mechanical and beryllium copper for electrical.

https://www.ebay.com/itm/1x-Berylli...hash=item2a933bc15b:m:mX6qfnhSGVzVOzg1AHsmUnA

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I found a quick video, you can also use the shaft of a screwdriver to wind springs.

I'm a little late to the party...this also may have been a case of a short or another defect within the tail cap. I have run 3A through the small caps with no problem, though I have not tried 5A or higher.

His little late but as Red says you can make your own springs. I did in the past and the technique Red shows is the way. When I wound my springs I would heat them Red hot then dip them I oil to temper them so they retain there shape.

Rich

Making a replacement spring from a more conductive material could be a good idea. The problem with many battery springs is that they are made out of poorly conductive steel.

It doesn't even take that much, i've seen some video in which someone had one of those usb powerbank things where you insert your own 18650 cells, all just in parallel. He got the first one on, and the put the second one in the wrong way around - spring was glowing red hot and then just detached from the bus bar (or broke due to melting).

Who would show a video of themselves making such an idiotic mistake? That seems like the kind of thing you'd want to keep to yourself and make a mental note not to do it again.

"Here's me putting a battery in backwards and melting the contact spring. I guess I'm lucky it didn't explode in my face. Likes?"