You can use the top of an old 9V battery as a 9V battery clip for assorted
electronics projects. The "9V clip" is also used on some batter holders of
assorted voltages (ie a 4AA battery pack.)
Here's how to make a nice wire-lead version...
(This is an old idea. The only original part here is the "strain-relief" hack.
Still, new pictorials for old ideas can be pretty useful.)
Step 1: Find a Dead Battery...
Find a dead 9V battery. Batteries are supposed to be recycled these days,
so a good place to find dead one is at work, where they might have battery
The internal construction of 9V batteries varies a great deal, and some are
easier to convert to clips that others. Duracells are pretty good.
Step 2: Clip the Casing
Using wire or other cutters, clip the corners at the top of the casing.
Step 3: Peel Back the Edges
Use clippers or pliers of some kind to peel back the folded-over
edges between the cuts you made in the last step. Be a bit careful;
those edges are sharp!
(On some batteries, the bottom may be easier to open than the top, and
that will work just as well for our purposes.)
Step 4: Separate the Parts
You should be able to push out the guts of the battery from the bottom;
you should end up with the top, the cells themselves (may be attached
to the top by wires or straps), and a plate from the bottom.
Step 5: Separate the Top
If you're lucky, there are metal straps spot-welded to the contacts, which
are easier to solder to than the contacts themselves. Cut these near the
batteries so that you have some left to wrap around wires. (Here, one of
the spot-welds has failed, so it will only be half-easy)
Step 6: Prepare to Solder on Wires.
Wrap wires in tabs, and vis versa, if you have tabs. Maybe clean up
the contacts a bit...
Try to be consistant about which colors go to which contact. I try to use the darker
color for the negative contact ("male" nipple. Remember that it's reversed from the
polarity of the battery itself.)
Step 7: Solder...
Go ahead, glop on the solder. Some batteries have relatively heat-resistant
insulating material holding the tabs (another plus for duracells.) Other batteries
use normal plastic, and you'll have to be careful not to melt it too much.
Step 8: Provide "strain Relief"
Loop the wires around a bit over the insulator, being careful not to short
out any bare copper to any of the contacts. This will provide quite a lot
of strain relief in the finished connector, and help prevent the wires from
pulling off the contacts during normal handling.
Step 9: Attach Backing
glop on some hot glue and attach the bottom insulator from tha battery to
protect the wiring and your fingers. You should use enough hot glue to
pretty much fill in all the space the wires will make between the insulators.
squeeze together gently, remembering that hot glue is ... hot.
Step 10: All Done!
You probably could have bought one of these for $0.15, but I'm sure
that this was a lot more fun...