How do you fasten a piece of wire to a battery?

You don’t, unless you’re planning to throw the shaver away when the battery is dead. Use springs to maintain contact.

Be careful heating up that battery terminal with your soldering iron. Some batteries don’t like the heat.

Tried super glue?

@jasongarrett: Long story short I need to fasten the wire to the battery.
@steelmarket: Yes, I tried that as well.

Most battery contacts are made of stainless steel and you would have to use silver solder. This is done before the battery is assembled because the heat destroys the batteries current holding ability.

I recommend you buy a battery with the contacts already connected.

SOME BATTERIES CAN EXPLODE WHEN HEATED.

Could you drill a tiny, shallow hole, insert the wire and hold it in place with a tiny screw? I am thinking of a screw as small, or smaller, than the ones used to assemble the frames for eyeglasses.

If you use a good flux to clean the terminal and wire, then silver solder to solder it will stick with no problem. I had to repair a battery pack for an 18V tool, one strap had came loose from one end of a battery internally. Resoldered, works great. Be careful when doing anything to a battery though.

There is no way to wedge the wire next to the battery in the compartment?

I wonder if liquid steel would work?

@pekenoe: No, the batteries are no where near the edges of the razor.

You need a conductive adhesive. These exist, but aren’t easily found. You can make your own using the following recipe (which I got here):

You’ll need powdered graphite (sold as lock lubricant) and DAP contact cement. Both are available at hardware stores. Mix 1 1/2 parts graphite to 1 part cement by volume. Use immediately.

I’m wondering if liquid steel would work then. You would have to make sure the wire was in good contact with the terminal before applying the epoxy.

@harp Cool, conductive adhesive. That I have got to try.

@pekenoe Liquid Steel is similar to JB Weld in that they both use powdered steel in an adhesive matrix, but JB Weld specifically states that it’s non-conductive and doesn’t work for electrical repairs, so I would think Liquid Steel would have similar properties.

A co-worker of mine is an electrical engineer, and he did it in practically no time. He scratched the ends of the batteries with a sharp knife, presoldered them, and soldered the (presoldered) legs of a resistor to them. And it worked great. I suspect it’s primarily a case of being skilled with a soldering iron. There might be a bit more to it than I thought, even though I’ve soldered countless things in my time :-)