On Saturday, 16 May 2020 20:35:02 UTC+1, Paul wrote:

It's pretty hard to make battery springs as a DIY.
A metal that makes a good spring, makes a poor
battery contact, and has to be plated up with other
metals to make a good finish.

Paperclips & springs off batteries & battery holders work ok. The finish is usually chrome and relies on enough pressure to get an electrical contact.

This also leaves
the spring susceptible to corrosion from
battery "fluids".

all are.

https://uk.rs-online.com/web/c/batte...contacts/?pn=2

Random sample solution: £0.343 bag of ten contacts D sized, they say.

https://uk.rs-online.com/web/p/batte...tacts/1724915/

The problem with any of these, is how to affix electrical
connections. You could use, say, a #2 screw and a solderless
terminal to go under the backside of the spring. But what
usually happens with solutions like this, is the screw ends
up protruding out of the plastic housing, as there isn't
usually room for a retrofit.

rivet


Solder never sticks all that well, or the
result is brittle and some wire snaps off later.
(Like if you tried a kind of silver solder.)

then you've got a chrome plated spring. Rivet instead, or screw if it fits.


NT

You would need to see how much the spring compresses,
to see whether a screw-head would fit in the end terminal
area. That's why a #2 might be all that works.

Paul