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Estimated Length of time running on a 9 volt Battery... — Parallax Forums

Estimated Length of time running on a 9 volt Battery...

Joe CoffeeJoe Coffee Posts: 2
edited 2006-03-01 06:59 in BASIC Stamp
Hello,

·· I was wondering if anyone had a good guess as to how long a homework board built project would last running on a 9 volt battery?· The program itself would have relatively little action, primarily listening for events before doing its programmed functions.· Any guesses??· I simply want to know if a project can be housed up in a remote location for days at a time or should I consider a renewable energy source to recharge/power my device such as solar power??

Thanks a ton!

coffeebean...

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2006-02-16 18:51
    Think it'll come down to how well you take advantage of 'SLEEP' and 'NAP'.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-02-16 19:22
    That is correct, as well as what you're driving (LEDs, etc.) that may draw additional power from the battery and anything else connected to Vin or Vdd.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • SteelSteel Posts: 313
    edited 2006-02-16 20:10
    I would consider alternate power supply just for a more robust solution.

    Solar panels are a great idea....much better than a mouse on a wheel.

    A 12V car battery with power conditioning may work rather well, depending on the power consumption of your product.
  • Terry KingTerry King Posts: 12
    edited 2006-02-16 20:24
    Take a look at:
    http://www.emesystems.com/BS2power.htm
    for a detailed look at PS2 power (Maybe more detailed than you wanted) smile.gif

    "BASIC Stamp power supply, SLEEP & brownout" is the title. Also shows a BUG in BS2
    that MIGHT bite your battery...

    ...Lots of good stuff on that site!

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    Regards, Terry King ...On The Mediterranean in Carthage, Tunisia, North Africa
    American Cooperative School of Tunis
    terry@terryking.us
  • allanlane5allanlane5 Posts: 3,815
    edited 2006-02-16 22:19
    I've wondered this myself. The "it depends" is not a very helpful answer. Has anybody actually done the lab with a 9-volt Alkaline, with NO sleep, NO pause, and measured the duration?

    Then, of course, throwing in Pauses and Sleeps would extend it, of course.
  • SteelSteel Posts: 313
    edited 2006-02-17 00:01
    ^^^
    Which lab? The reason why "it depends" is because there haven't been any specs on what loads are applied to the specific project, and what the operation circumstances are around the project.

    If he is powering 2 LEDs vs 200 LEDs, it is going to be different.

    I have a project that has 2 Stepper motors, an LED, a Radio Reciever and an optic source, and my battery lasts a whopping 45 minutes before I begin getting brown-out resets.

    If his project is going to be un-manned for several days at a time, it may be beneficial to get a solid powersource that is meant for being powered on for several days at a time.
  • Tracy AllenTracy Allen Posts: 6,664
    edited 2006-02-18 18:39
    A 9V alkaline battery has about 600 milliamp hours of capacity. Your ballpark calculation:

    hours of operation = 600 / (average current consumption of your project)

    Say your project draws an average current of 6 milliamps. Then the battery will last around 100 hours.

    The hard part might be figuring out the average current. It is a time weighted average of the current drawn by the stamp and its peripherals, while awake and powered up, and the current drawn during SLEEP or NAP periods. It is like drawing up a budget, carefully, and seeing where you can save and trim.

    All batteries are not equal. The capacity will change at extremes of temperature, if that is an issue in your remote location. If it is truly remote and there are extremes of temperature and you want the longest life, get a lithium battery. www.energizer.com has some great technical and educational information.

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    Tracy Allen
    www.emesystems.com
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-02-19 06:30
    Take a look at the web site that Terry Allen mentions...
    It never occured to me that the actual position of the sleep command in eeprom could waste so much enery.

    Part of the problem is battery
    Part of the problem is software in the BS2
    and
    Part of the problem is peripheral circuitry.

    Seems you will have to just build and test.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • Joe CoffeeJoe Coffee Posts: 2
    edited 2006-03-01 06:59
    unbelievable!· i get sidestepped with my everyday job and forget to check this post and i come back to discover that there are quite a few replies!!·· this is all quite excellent information...thank you very much Tracy Allen for the mathematical breakdown..that will become invaluable as i try to determine the best powersource to use....thanks Terry King for the link!· I am going there now...

    thanks to everyone else who replied, you can never have too much information!

    i hope to be able to return the favor in these forums sometime soon!



    cheers...
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