I’ll be going out to Provo, Utah for the Novell ( Attachmate? NetIQ? SuSE? ) TTP Conference. I’ve been in the habit of shooting time lapse series in the evenings and free time ( what’s that? ) while I’m out there – as its a very different place from the verdant rolling hills of Eastern Pennsylvania. I normally use a portable AC supply, which is an integrated 12 volt 20 Ah battery + inverter. So while the battery itself provides about 200 watt-hours, it can only power the camera for 12 hours. It weighs about 20# – so not really something you want to carry around or take on a plane. The underlying problem is that the camera needs 8.4vdc, which comes from the AC adapter, which is fed by the inverter, fed by the 12v battery. So there is a lot of waste and inefficiency. The camera itself uses only 4 watts, and the AC adapter uses 20 watts! So already we are at 75% waste. Also the power pack needs to be protected from the elements – and it uses house current, so dangerous when wet. Other than that, its great!
So I built a DC-DC power supply using off the shelf components: 2000 mAh AA NiMH batteries, an 8 AA cell battery holder from Radio Shack, and a DC-DC switching power supply. The DC-DC converter is a very cool. It has a 20-turn potentiometer to adjust the voltage out, and decoupling capacitors on the output so no external caps are necessary. Its about the size of a nickel. And it accepts Vin up to 30 volts! I created a harness so multiple DC-DC modules can be dialed in to the desired voltage and easily swapped out depending on the camera used.
Here is my old F30 powered from a SLA via the DC-DC module set to output 5.0 vdv ( as seen on the volt meter ).
Here is my S100fs – my current time lapse workhorse powered off another DC-DC converter set to output 8.4vdc.
The S100fs itself draws about 440 ma from the 8.4 vdc side of the DC-DC converter. Or about 410 ma from the 9.6vdc supplied by the 8 x AA batteries. The batteries are rated at 2200 mAh, so “should” from, the numbers, power the S100 for ~5 hours. ( 2200 / 410 )
Here is a jumble of parts that make up the rig. The battery is connected between the Yellow ( Vin ) and Black ( common / ground ). The redulated output is on the Red ( Vout ) and Black ( common / ground ). The output lead is a scrap lead from a multi-voltage batter replacement gizmo – this gives me multiple tips, but in fact all my Fuji cameras and my Canon HV-series video cameras use the same one.
After cleaning it up a bit you have a 9v snap connector connecting to two of the Radio Shack 8-cell AA battery holders – each produces 9.6 volts, and is placed in a series configuration using a modified 9v snap connector ( on the top above the read / black leads. Remember, provided we can supply the converter with more than 8.4 volts, we are set. So I can use a single batter holder ( 9.6 volts ) or both in series ( 19.2 volts ).
Here is a better view of the two battery series configuration. The top most snap connector connects the batteries in series, and the bottom feeds the DC-DC converter. This configuration will power my S100fs for 11 hours of continuous usage and provide for taking > 12,000 pictures!
All the basic pieces: battery, wiring harness, regulator, modified snap connector, and yellow tipped connector. The translucent bead of stuff on the output wiring is silicone ear plug material, which I form into a bead. The bead is squished when the wiring is closed in the water proof box ( next image ).
The whole mess in a waterproof case. Obviously I could use one which is slightly less deep.
All dressed up and ready to go! A single battery holder will power the camera for about 5 hours allowing a full series of >12,000 11MP pictures to be taken. The second pack is needed when doing longer series, such as over night.
One modification would be adding a second input snap connector to allow for packs to be used in parallel – this would allow for them to be swapped out without interrupting service.