On Apr 25, 4:56*pm, Jeff Liebermann <je...@cruzio.com> wrote:
> On Fri, 25 Apr 2008 06:18:16 -0700 (PDT), Adam Chapman
>
> <adam.chap...@student.manchester.ac.uk> wrote:
> >> I've done that. *You're about to have a battery problem.
>
> >Do you think an 11.1V battery would do the trick? Im looking at this
> >one
> >http://www.flightpower.co.uk/index.asp?page=Products/index.asp^currency=GBP
> >At the cost of another 40 grams i could use a 14.8V battery and put
> >some resistors in.
>
> Which battery were you thinking of? *I'm not going to pick one for you
> as there are quite a few on the site. *Is this going to also power the
> servos, receiver, propellers, etc or just the camera? *You do the
> numbers, and I'll check the results. *I'm not doing your homework for
> you.
>
> The specs say that the camera at:
> <http://trendnet.com/products/proddetail.asp?prod=110_TV-IP301W&cat=48>
> show that it has a 12v 1.5A wall wart. *That's not what it draws in
> power, but that's what the power supply delivers. *Your first step is
> to *MEASURE* what it really draws. *Don't be suprised if you get wide
> variations depending on what the camera is doing, whether the IR
> illuminator is running, frame rate settings, etc. *Use and adjustable
> voltage power supply and see what voltage range the camera can
> tolerate. *My guess(tm) is that the camera will run down to perhaps
> 8VDC or maybe even lower if it has an efficient switching regulator
> inside. *Measure the current at various points and calculate the
> efficiency. *I wouldn't be suprised if the camera can run on a 2 cell
> battery pack (7.4VDC).
>
> Once you know how much energy (i.e. watts/time) is required. *LIPO
> batteries have a maximum current draw spec which should not be
> exceeded or you kill the battery. *Watch out for so called "burst"
> current ratings on the batteries. *It's the battery that will burst if
> you go over. *Be sure to allow for temperature variations as it has a
> huge effect on battery capacity. *I'm not sure what percentage of the
> capacity of the battery you can discharge down to, but if you go too
> far, you also kill the battery. *You'll need to know this number. *How
> long were you planning on draining the battery, which really means how
> long is this thing suppose to be in the air? *If it powers just the
> camera, you can turn it off for the takeoff and landing, thus saving
> energy.
>
> Anyway, do the numbers. *No Mathcad model needed for this one. *Just
> some measurements and arithmetic.
> --
> Jeff Liebermann * * je...@cruzio.com
> 150 Felker St #D * *http://www.LearnByDestroying.com
> Santa Cruz CA 95060http://802.11junk.com
> Skype: JeffLiebermann * * AE6KS * *831-336-2558

Sorry i didnt realise the link was for the list rather than the
specific battery i chose. This battery will only be powering the
camera and onboard wireless stuff. I just wondered if 11.1 volts would
be enough. Your view was similar to mine, that the camera has a
tolerance. I should be able to get 13 minutes out of the camera, and
if we run out of power for the camera in flight, we can just land and
plug a spare in.

Thanks
Adam