Battery placement

Click to view full size

The above image shows Floyd with the back cover and the battery cover removed.  The yellow feature is the display bed, it does tripple duty. It holds and positions the display, it centers the buttons and it works as a light guide for the indicator lights. The right side of the PCB is the high-current area. The external power input and the battery charger sits in the lower part of this area.

The lower end of the case holds the batteries. These are currently 4 LiPoly, 18650 size cells in a 2s2p configuration. The 18650 cells have some great advantages:

  • They can be had in fairly high capacity
  • They are available in a variety of chemistries
  • They are fairly inexpensive, even matched and packaged cells
  • They weigh next to nothing
  • High discharge versions are available
  • Multiple sources worldwide

A major disadvantage is that these cells are cylindrical, so they waste a lot of room.

Click to view full size

The image above shows a cut through the unit revealing the back. The batteries are pretty large. A prismatic (flat) LiPoly battery of the same capacity could be made almost half as thick, but the cost would be a lot higher. Why not use AA batteries? AA batteries would deliver less power for the same size and weight. So the battery life would be shorter. Or we would have to fit, say, 12 AA batteries making the unit bulkier and quite a bit heavier.

Click to view full size

The above cut shows a bit of the front and this view gives you a sense of how much room the electronics require. We can easily make the rest of the unit 15mm thick (5/8 in) or even less. The cylindrical batteries doubles the thickness. We have put them at the base to keep them a cool as possible, and to keep the unit thin. Attaching them to the back would make the unit lower and more stubby.

Nothing is final regarding the batteries and I don’t think we have found the right power solution just yet. Any thoughts? Hit the comments…

7 Responses to “Battery placement”

  1. I’d vote up the external power idea as well. The truly unique part of this project is the “smart light source” aspects and I hate to see something as simple as power hold it back. Something available in commodity quantities that uses standard cells would be quite enough for V1. If the connector is standard, you could make the “ultimate smart light power package” a decoupled project.

    Good luck!

  2. I use Litepanels knock-offs. They come with a v-lock mount on the back. We ran them for 6 hours on one battery.

    This made me wonder about capacity for duration vs capacity for high output? I just found this site (and I’m dyslexic) so I’m not aware of the specification as far as burn-time/brightness for the light.

    I’m excited by the idea as it’s clearly going to be a great bit of kit.

    • Hi Matt
      We’re still struggling with the right balance of output versus duration versus bulk and weight. We’ll figure it out during beta testing I hope!

  3. I agree. An external source is a very good way to go, or a least something like a cable that can attach to a p-tap from a professional battery like an Anton Bauer or V-style battery.

  4. Why not make the power source external just like the external flash power packs?
    External power can then be AC power or a power pack.

    Other alternative is maybe something like what the field monitors do? Snap one or two camera batteries onto the back for power.

  5. Would certain camera/DSLR batteries work?

    • Yes in principle, but it depends on 3 things:
      – What is the voltage of the battery? It should be between 7 and 17 volts, currently
      – Is the battery powerful enough? If the battery is very small, it may not be able to power the light at full brightness.
      – How can the battery be connected? Currently, there are no custom battery holders. Maybe there should be?

      When we get the new prototype working, I’ll test a few typical DSLR batteries to see if they can work.

Leave a Reply