Battery for a wireless module

Discussion in 'Wireless & RF Design' started by rogerthatpsr, Oct 29, 2009.

  1. rogerthatpsr

    Thread Starter Member

    Aug 22, 2006
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    I am working on a RF portable module that operates as a transponder.. works @ 2.4Ghz, battery operated...every 5 or 10min once it wake's up, transmits few bytes of data n goes back to sleep mode.... its spec >> 45 mA peak transmit current n sleep current < 10uA... the device is expected to work for 5 years..... i wanted some info on wat kind of battery to use n any modifications required ?? (operating voltage 3.3v) any kind of info related to this would be helpful...


    Thank you
     
  2. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    A solar charger...
     
  3. BMorse

    Senior Member

    Sep 26, 2009
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    A solar charger itself is NOT a battery, the op is asking for info on batteries, not how to charge them!
     
  4. BMorse

    Senior Member

    Sep 26, 2009
    2,675
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    Check out Lithium batteries..... one should work for your application.... here is one at Digikey....http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=439-1000-ND

    My .02
     
  5. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    You're going to need a very efficient regulator to get 5 years @ 3.3V
    How long is the transmission time? 1 sec, 5 sec?
     
  6. BMorse

    Senior Member

    Sep 26, 2009
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    you can try one of these IC's from maxim http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4770/t/al ..... they are step up dc to dc converters that can take a 1.5 and put out up to 5.5 volts (can be configured for 3.3 volts) try the Fixed 3.0V or 3.3V Output Voltage MAX8569B.

    My .02
     
  7. rjenkins

    AAC Fanatic!

    Nov 6, 2005
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    Some types of Lithium cells are rated around 3.6V
    Have a look at 'Lithium thionyl chloride' parts.

    You may find the 3.3V device has a wide enough tolerance to handle that directly (which means it would probably still work when the battery is down to under 3V).

    If it can't take that much, connect a small schottky diode in series with the battery, that will drop the voltage slightly and give roughly 3.3V out.

    Here are a couple of examples, 'D' size cells:

    http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=5268481
    http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2019466

    These are 19AH and 16.5AH - one cell would give you hundreds of hours of total transmit time and / or many years of standby, probably enough for your application.
     
    Last edited: Oct 29, 2009
  8. BMorse

    Senior Member

    Sep 26, 2009
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    pretty much what I said, just paraphrased.....:cool:
     
  9. rogerthatpsr

    Thread Starter Member

    Aug 22, 2006
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    0
    Thanks for reply BMorse n rjenkins...
    i went thru all of these battery n ur suggestion. it will definitely fulfill my spec... but is there any battery discharge optimization required, ie the module draws current from battery in the form of pulses whenever it has to transmit... usually batteries last long only if they are discharged at constant rate.... is there anything to connect between battery n module that acts as a buffer(with low loss)... a simple LC circuit would fail cos inductor itself consumes some energy....any suggestions ????
     
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