18650 Battery Tube

[Green Lantern]

Hey everyone!

I am just about to start my next project (I will not tell you what it is quite yet ) but I need a part for the battery tube I will be making. I need an electrically conductive spring to keep the battery in place, but also that I can solder wires onto. Let me try and explain how it will be setup.

I need two springs, one for each end, because the battery is going to be rechargeable and permanently mounted into the tube. The tube is going to be a plastic dime tube and have holes drilled into each end for the wires to connect to the spring and run out the ends. Between the springs is going to be a circuit protected 18650 battery (so there is no nipple on the positive side). To give you an idea of how long the springs should be I will have around .5 cm on each side of extra space. Another option is to have a spring on one end and a clickey switch with a spring on the other. Whatever works.

Can I just use any spring from the hardware store? Shouldn't they be conductive and made for batteries? Where would I buy these? Is a dime tube okay or will it melt?

Sorry for my confusing description. Anything you can say could be of help.

-Green Lantern

EDIT: Perhaps a better question is: how can I build a battery pack for this 18650 battery for less than $5 USD? http://www.dealextreme.com/details.dx/sku.1283 I have the dime tube, so I thought that would be the simplest. I am open to any other suggestions you may have.

 

[Torque1st]

Re: Electrically Conductive Spring

A spring is only needed on one end. Use a small metal contact button on the other end fixed in place with an adhesive. Any hardware store spring will be electrically conductive and you can solder to them. Acid core solder will work, just clean the flux off after soldering. A cut down spring from an old flashlight will work also.

 

[Green Lantern]

Re: Electrically Conductive Spring

A spring is only needed on one end. Use a small metal contact button on the other end fixed in place with an adhesive.

Hummmm.... Where might I get one of these metal plates you speak of?

 

[gadget_lover]

Re: Electrically Conductive Spring

Just use tin snips to cut a small strip of metal from a tin can (vegetables).

Create the contact button by setting the metal on a board, and whack the head of a nail into it. That will cause a bump on the other side.

The shiny side of a 'tin can' is conductive. The inside is generally coated and non conductive.

Daniel

 

[Green Lantern]

Very interesting solution... Thanks for all the help guys. If anybody else has a suggestion on the easiest way let me know.

I never expected these things not made for electrical appliances to be perfectly conductive. I assumed that you would need something made to handle electrically. Very cool to know, and thanks for the help.

 

[Torque1st]

Metals are by definition electrically conductive. Some are better conductors than others but with the type of currents we use with most LED's they all work well. If the current is known and the cross section, length, and material is known then the voltage drop can be calculated. The voltage drop is small with small currents.

As far as the button terminal a drop of solder can also be used as a contact point instead of a deformed bump.

 

[Oznog]

You can get a wide variety of clicky switches dirt cheap from DealExtreme.com or KaiDomian.com. Some have an integrated spring.