Portable Power for Timelapse Rig

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.

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