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Powerconsumption: How long will i run this on a 9V battery? — Parallax Forums

Powerconsumption: How long will i run this on a 9V battery?

CrosswindsCrosswinds Posts: 182
edited 2011-12-16 07:05 in Propeller 1
Hi guys!

Im working on this project with my Professional dev board, and sometimes i want to be a bit more mobile with it, so i was wondering if there is a possibility to get a decent time out of a 9v battery:

I do understand that this is probably very much code dependant, but let me breat it down the best i can:

2 Led´s (Not constantly on)

1 cog that runs a freq generator code for LED dimming,

1 cog that run all the other code.

I will communicate with the propeller with the parallax serial console, (Via usb)

That pretty much is it.

What do you think about this? What are we talking about here, 1 hour or 24 hours?



Best regards
Daniel

Comments

  • LeonLeon Posts: 7,620
    edited 2011-12-13 09:28
    Measure the current and estimate the battery life using the battery data.
  • max72max72 Posts: 1,155
    edited 2011-12-13 09:42
    I usually prefer 4 AA rechargeable batteries.

    You could use a USB powered board, too..
  • Mike GreenMike Green Posts: 23,101
    edited 2011-12-13 09:46
    The Propeller datasheet has graphs that allow you to determine approximately how much current it draws under what circumstances. The current consumption depends heavily on how many cogs are running and how fast the clock is running.

    Anything you attach to I/O pins (like LEDs) adds to the current consumption. Since you're using USB, that can supply power and you won't need a 9V battery at all. You won't be able to use the PPDB's USB interface for power though and the PPDB's regulator also uses some current for itself. Check the PPDB's schematic and the regulator's datasheet for details.

    For examples of Propeller boards that run off USB power, have a look at the QuickStart board and the Propeller C3 board.
  • rokickirokicki Posts: 1,000
    edited 2011-12-13 10:15
    Your battery life will probably be dominated by the current consumption of the regulator used. If I recall, that
    regulator requires 10ma (even with the output not drawing any current). At 10ma, a typical Alkaline 9V
    battery will last about 56 hours. At 10ma, four AA batteries will typically last 250 hours.

    I base this on earlier measurements I made of the demo board and my memory of that; the regulator on the
    dev board may be different.

    [Additional data added later: I can't find my post on my original current measurements. Not sure why 10ma
    sticks in my mind. Anyway, the actual regulators appear to be *2ma* quiescent, and there are a pair of
    them, so that accounts for 4ma, so the above numbers can be multiplied by 2.5 just taking into account the
    regulators alone. If you crank the Prop up and use a lot of cogs or video or some such, the numbers will
    change appropriately. But I think you'll be surprised how well it works on batteries.]

    But like others have said, running off USB, you can frequently get all the power from USB too.

    -tom
  • CrosswindsCrosswinds Posts: 182
    edited 2011-12-15 13:30
    max72 wrote: »
    I usually prefer 4 AA rechargeable batteries.

    You could use a USB powered board, too..
    Thank you! Thats a good idea..

    Mike Green wrote: »
    The Propeller datasheet has graphs that allow you to determine approximately how much current it draws under what circumstances. The current consumption depends heavily on how many cogs are running and how fast the clock is running.

    Anything you attach to I/O pins (like LEDs) adds to the current consumption. Since you're using USB, that can supply power and you won't need a 9V battery at all. You won't be able to use the PPDB's USB interface for power though and the PPDB's regulator also uses some current for itself. Check the PPDB's schematic and the regulator's datasheet for details.

    For examples of Propeller boards that run off USB power, have a look at the QuickStart board and the Propeller C3 board.

    Thanks for your reply!

    I would very much want to use the ppdb for this, is there a way to feed it via usb?
    rokicki wrote: »
    Your battery life will probably be dominated by the current consumption of the regulator used. If I recall, that
    regulator requires 10ma (even with the output not drawing any current). At 10ma, a typical Alkaline 9V
    battery will last about 56 hours. At 10ma, four AA batteries will typically last 250 hours.

    I base this on earlier measurements I made of the demo board and my memory of that; the regulator on the
    dev board may be different.

    [Additional data added later: I can't find my post on my original current measurements. Not sure why 10ma
    sticks in my mind. Anyway, the actual regulators appear to be *2ma* quiescent, and there are a pair of
    them, so that accounts for 4ma, so the above numbers can be multiplied by 2.5 just taking into account the
    regulators alone. If you crank the Prop up and use a lot of cogs or video or some such, the numbers will
    change appropriately. But I think you'll be surprised how well it works on batteries.]

    But like others have said, running off USB, you can frequently get all the power from USB too.

    -tom

    Thank you very much sir four your informative answer!

    Also i think that usb would be great, but i thought that it would be more simple to use a battery, but a way to feed the ppdb with usb would be the best!:)
  • max72max72 Posts: 1,155
    edited 2011-12-15 14:39
    If you are looking for a USB powered solution:
    I don't know of ppdb hacks, probably the cost of the board is too high to play with it..
    There are proto board hacks available (a usb protoboard is much cheaper).
    If you simply need some leds consider also the quickstart. USB powered, 8 leds, 25$....
    Massimo
  • bozobozo Posts: 70
    edited 2011-12-15 17:52
    I modified the USB cable for my PPDB to do exactly this,

    On the USB cable:
    - cut the USB cable near the end that connects to the PPDB
    - feed on some heatshrink tubing on each wire
    - strip the wires and rejoin them all
    - add a black and a red wire to the power wires
    - shrink the heatshrinkable tubing over all the joints
    - solder the red and black tap wires to a 2-pin header

    On the PPDB:
    - add a jumper from the +5v female header to one of the power rails on the prototyping board
    - add a jumper from earth female header to the other power rail on the prototyping board

    plug the USB cable in to the USB socket as usual, and plug the 2-pin header with the power taps into the two power rails in the prototyping board.

    Bingo. Portable PPDB powered from USB, without having to hack into the board itself.

    Drawing34.jpg

    Cheers,
    Mark
  • Mike GreenMike Green Posts: 23,101
    edited 2011-12-15 20:55
    Do keep in mind that the 5V power carried by the USB cable may not be 5V at all. It may be a bit lower. That's not a problem for stuff running at 3.3V from the 3.3V regulator, but it may be a problem for 5V devices running off this power source.
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2011-12-15 21:59
    Why wouldn't you take the +5V off from the USB socket rather than the cable? I'm sure that even if these is only a little bit of pad there it would still be accessible with a bit of finesse. Also the voltage drop is dependent upon the length and quality of the cable used. I have some USB cables that are useless for charging as the conductors are so super fine. However I have more and more designs which get their power exclusively from the USB port or even via a dedicated microUSB socket as 5V 500ma plug-packs (Wall-warts) only cost me $1.59.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2011-12-16 06:02
    USB is indeed useful for +5v if you must - but it is only 500ma and only +5 at best.

    Since I do most of my bench work next to my PC, I just wired a floppy power plug to a DB9 that is provided in an empty card slot at the rear of the PC. I have both +12 and +5 in copious amounts and well-regulated. The +12 occasionally drives a relay that turns on an 120 VAC box when I turn on the computer - very handy as well.

    In fact, I can use the DB9 to provide adequate +5 as for my Seagate USB harddisk which requires close to 1 amp of +5. The USB port was never meant to be an all-purpose power takeoff - the primary targets were keyboards and mice. The wires are thin and contribute to the voltage drop.
  • BigFootBigFoot Posts: 259
    edited 2011-12-16 07:05
    One of our propeller based products (PAD) includes a 2 line x 16 LCD, bar code reader and Biometric finger scanner
    runs for about six hours with four AA rechargeable battery s.
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