DIY Battery Power supply for dSlR rig and LCD

Asa

Asa

Well-known member
Hello folks,

I'm considering building a DIY battery pack for my D800 and LCD screen. Ideally I'd like something equivalent in performance to a Paul C Buff Vagabond, but in general something that will power both camera and LCD for 5+ hours would be ideal.

Has anyone built something like this? Seems like it should be pretty simple from a wiring/electrical perspective. I was thinking of buliding it into a cheap suitcase so the outlets/charging connectors would be on the outside.

I can buy the battery that goes in the Vagabond Mini for $90 directly from Paul Buff. And wiring in a dc to ac converter and a couple of plugs doesn't seem a big deal.

Or I can buy a set of deep-discharge batteries and build something like this:

http://nightskyinfocus.com/diyprojects/diy-field-battery/

I'm just starting on the plans for this project, so any input is appreciated. I also haven't yet run the calcs for how exactly how much power my camera and LCD draw, but will post when I get a chance to do that.
 
Y'know, I'm no expert on all the battery systems out there... there is a thread in the Nikon forums about powering a Nikon 5200 by rewiring the battery-socket adapter thing.

But if you're doing (or planning on doing) client work, I'd look into existing setups that mount to rails or a belt, etc... vs. wires coming from a suitcase.

I'd think you'd want to skip all the DC-AC stuff, inverters, etc... cameras and LCDs are designed to run off battery-type sources, going out via AC and back through transformers (I'm assuming here) seems like more complexity, mess, and maybe power-suck. What you're wanting likely exists, or exists in a 95%-there state, already in a form factor that plays well with standard cinema-style gear. Hunt around a little more, I'd imagine there's plenty of existing stuff.
 
Well, I've put this on the back burner while I finish building my doorway dolly.

I know there's plenty of existing stuff out there, but what I've seen is expensive.

Only reason I mentioned a DC to AC converter is because then you could use standard AC adapters with the unit (as well as power lots of other things). This seems easier and safer than hacking a DC power supply adapter and wiring it directly to 12volt as that would give the incorrect amperage for the unit. Maybe I'm wrong on that. I'm less worried about it for my cheap LCD screen than I am for my $3k camera.

This is the closest thing commercially available...and yeah, you're right, it's small and reasonably affordable:

http://www.paulcbuff.com/vagabond.php
 
I'm not sure what you are looking for, but I don't see why you would need a DC to AC converter, as it would be a likely source for noise that you don't want, particularly on the audio track, even if you use balanced mic lines.

What you would need is two external batteries: one for the Nikon and one for the portable LCD screen.

Let's hope you are not considering an AC powered LCD screen, because most run only on AC power and need plenty of it. If so then you would have to find out on professional audio gear companies, like Trew Audio, what DC to AC converter they do recommend.
 
or use something like this: http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=16225 , the amps don't really count, the more the better, the camera, or whatewer equipment you have will draw only as much as it needs, not more, just be carefull at the voltage, so it matches the consumer. These are rather inexpensive, and a lot less bulkier than a lead acid battery, and you can choose from a lot of batteries, which even by my standards are cheap. I haven't quite figured it out why camera gear so f@#$%ng expensive, it probably has something to do with the colour black.
 
Converting DC to AC is inherently inefficient and to get much power, for any duration, will take more battery than you want to carry. DC power will create less RF interference as well.

"This seems easier and safer than hacking a DC power supply adapter and wiring it directly to 12volt as that would give the incorrect amperage for the unit".
That statement is simply wrong. The amperage a device uses will always be controlled by the internal resistance of the device and it will only use what it needs. Voltage is what you need to control.

Most small DC devices in video and audio that use wall-warts use about half a dozen pretty standard mini-plugs which are (generally) center pole positive, some manufacturers like Sound Devices use the very nice Hirose plugs, and most everyone else uses 4 pin XLR. If you look around, most of these plugs and or adapters can be found in the backwater pages of BH or Markertek (they also build custom cables). Another way to go is to use something like the BDS (battery distribution system) from Trew Audio and power it with anything from a AB battery or even a cheap Bescor brick. Another pretty decent option is the Tekkeon batteries which have mutiple voltage options as well as a 5v usb port and come with a pretty good selection of plugs. I use a tekkeons with a custom distribution cables to power my audio bag, monitor, and more. Works good for me.

Grant
 
There are some good, efficient DC regulator modules available now which can take your bulk source (battery pile) and create lower, regulated voltages for all the gear that needs something precise.
For example I have several cameras that want 7.2 volts, and these regulator boards from MPJA are perfect for powering them from a 12V DC source (battery, etc.)
Great, modern, efficient switch-mode design using monolithic regulator ICs, and at quite remarkably low prices...

Step-down (buck): input: 4.5 ~ 40V, output 1.3 ~ 37 V @ 2A
http://www.mpja.com/LM2596-Step-Down-Adjustable-15-37V-DC_DC-Converter/productinfo/30148 PS/

Step-down (buck): input: 4.5 ~ 40V, output 1.3 ~ 37 V @ 2A -- with built-in voltmeter! (shown in photo below)
http://www.mpja.com/Adjustable-15-37V-DC_DC-Buck-Converter-with-LED-Volt-Meter/productinfo/30149 PS/

Step-up: input: 3~34V, output: 4~35V @ 2 amps
http://www.mpja.com/LM2577-Step-Up-Adjustable-4-35V-DC_DC-Converter/productinfo/30300 PS/

No, I am not a shill for National Semiconductor, Texas Instruments or MPJA.
But I am a fan of good modern technology at low prices.

30149.jpg
 
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