I built this adapter in order to add larger battery capacity for prolonged time lapse shooting, it will work for adding battery hours to your camera or anything at a fraction of the price of commercial options.
Be aware that messing around with electricity can be dangerous to you and your equipment, if you are not comfortable with this, do not do this.
Step 1: What you need
- 1 battery for your camera. search on ebay or amazon and buy the cheapest one you can find, it doesn't have to work well it just needs to fit in your camera.
-2 DC to DC step down. Ebay again, just a few dollars. I used this one. http://www.ebay.com/itm/250954119681?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
-3 Small enclosure for the step down.
-4 One DC power jack
-5 One DC barrel plug
-6 12" of 1 pair wire or a couple strands of hook up wire.
-7 Shrink tube
Multimeter <------ THIS IS A MUST!
Step 2: Build it
Inside the battery case you will find a circuit board attached to the battery. You need to disconnect this; carefully cut the leads connecting them.
Now you need to solder the wire that will connect the DC to DC step down to the circuit board. On the backside of the board in the battery I used, there were solder pads for the battery contacts, identify the correct pads and solder the wires.
You will need to notch the battery case slightly where the wire will exit. Double check on your camera where the little flap of rubber is for the wire to go out so the battery door can still close. Tie a knot in the cable or glue it to the inside if the battery case so that you don't accidentally pull the wires off of the circuit board. Now glue the battery case back together.
Now, drill a hole in the enclosure for the step down. Solder a few wires to the 'in' pads of the step down, connect them to the appropriate connectors on the DC jack.
Plug the 12v or 18v (or whatever battery that you plan to use) into the dc jack, connect your multimeter to the 'out' pads on the step down and turn the adjustment screw on the step down until you see the voltage you want. Use the voltage from a fully charged camera battery as your guide. It may be a good idea to cover the adjustment screw with some hot glue so that it can not be moved accidentally. BE SURE YOUR OUTPUT VOLTAGE MATCHES THE VOLTAGE OF THE CAMERA BATTERY.
Solder the wire from the camera battery to the 'out' pads on the step down. Make sure you have the correct polarity. Notch out a hole for where the wire will leave the enclosure and close it up.
Now test it out with your multimeter, and test it again! Be sure you have the correct voltage and correct polarity BEFORE you put this in your camera.
OK, that's it! You can now power your camera with much larger batteries for long days of shooting, time lapses, or heavy video use.