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Power from 3v6 Lithium batteries — Parallax Forums

Power from 3v6 Lithium batteries

deSilvadeSilva Posts: 2,967
edited 2007-11-01 01:15 in Propeller 1
I run a Propeller from 3V6 lithium batteries for some time now without problems. The cheap type I use is AA sized and contains around 1 Ah.
Open circuit voltage is 3V7, when drawing 50 mA it drops down to 3V4.

I should consider this safe conditions (I know the datasheet says: 3V6!). Other experience?

Comments

  • hinvhinv Posts: 1,255
    edited 2007-10-30 00:13
    Can you point us to where you buy them?

    Thanks,
    Doug
  • deSilvadeSilva Posts: 2,967
    edited 2007-10-30 00:24
    You should be aware that I live far, far awy smile.gif
    www.lithium-batterie.de/html/allgem2.htm
    SL 760 is rated for 60 mA max - and it's even 2 Ah capacity
  • hinvhinv Posts: 1,255
    edited 2007-10-30 00:30
    When you say 3V6, you mean 3.6Volts right?
  • deSilvadeSilva Posts: 2,967
    edited 2007-10-30 00:40
    Yes.
    I made some research in the meantime. It seems I got them VERY cheap ($2) from overstock. I see offers upto $10 for one now.... I was not aware of that...

    Edit: A major producer is here: www.tadiranbat.com/iXtrac.php
    They give the "normal discharge" as just a few mA, but my experience is that you can safely draw the maximum value (20x) which is not always stated... However this is what I am unsure about...

    Edit2: Quite a science... www.tadiranbat.com/lithiumsnotalike.php Seems I am just lucky with my batteries smile.gif

    Post Edited (deSilva) : 10/30/2007 1:01:42 AM GMT
  • DarrenYDarrenY Posts: 61
    edited 2007-10-30 08:56
    I'm looking into a similar problem.

    I want to (preferably) run my system from a single 3.7v LiPoly battery.

    I haven't worked out my current draw yet but the system includes a GPS, Accelerometer, Gyro, Digital Compass, 2 x Digital pressure Sensor, RTC, ADC and DataFlash.

    The best i've found so far has been the 3.7v Varta AA-Size cylindrical 2600mA.
    Does anyone know of any better, or have any other recommendations?
  • kevin101kevin101 Posts: 55
    edited 2007-10-31 23:58
    You could get some 18650 size Li-ion batteries from dealextreme(http://www.dealextreme.com/details.dx/sku.3287). They're a bit narrower than D size batteries (18mmx65mm) but they are high capacity and have around 1.5x capacity discharge rate with protection so you dont over discharge them. If you want smaller, there is also CR123A size and some others. A 2 pack with a charger is like 20 bucks so you could charge one and use the other on your projects. There are also surplus li-poly batteries for cell phones and choppers that you could use if you really want polymer. Its Just a suggestion, but go for the 18650's. they're the best buy.

    Kevin
  • deSilvadeSilva Posts: 2,967
    edited 2007-11-01 01:15
    I still fight with the English language smile.gif I was talking of NON rechargeable batteries. Rechargeables are not called batteries in many other languages...

    When talking of rechargeables, there are many possibilities, starting from 3 times any 1.2V cells be it NiCd or NiMH. Their price/performance ratio is unbeatable, and there is an immense variety.

    Main issue might be that fully charged 1.2V cells in fact have 1.35V which adds up to 4 Volts , NOT going down at medium load, as they are high current devices (upto 10A and more).

    When it comes to size and/or weight Li-Ion or LiPo is of cause the device of choice. I see no advantage of LiPo over Li-Ion for most applications at the moment, this will change when LiPo becomes more mature.

    The small Li-Ion devices used for cameras are really sweet. Just opening any catalogue I found 640 different kinds smile.gif from 600 to 1800 mAh...
    European prices go from 5 Euros to 15 Euros. As Kevin101 said, chargers for them are reasonably priced...
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