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has anyone ever used an A23 battery to power a Stamp? — Parallax Forums

has anyone ever used an A23 battery to power a Stamp?

evergreenevergreen Posts: 43
edited 2006-06-05 15:30 in General Discussion
Has anyone ever used an A23 battery to power a stamp? How did it turn out? Which 5v regulator did you use?

I'm looking to only power a stamp, 12 bit ADC, and 3 transistors (TIP120).

Thanks.

Comments

  • Robert@HCCRobert@HCC Posts: 80
    edited 2006-05-27 08:27
    I am in the process of testing these to power my own project. I am using the 7805 to regulate the power. It can power the stamp, but I have not connected more than a DS1620 , and have not had it on long enough to see how long the batteries last. I wouldnt imagine very long, and having enough current to power much - I believe these batteries are rated at 30mAH. But it sure is nice having 12v in such a small,small package!

    Be interesting to hear what you accomplish if you use these bateries, so post [noparse]:)[/noparse]

    Alohas,
    Robert
  • MikeKMikeK Posts: 118
    edited 2006-05-27 13:09
    For Energizer brand, see http://data.energizer.com/PDFs/a23.pdf. It appears to be designed to supply sub-milliamp currents (~500uA for 80 hours to 6V in their test).
    Mike
  • GadgetmanGadgetman Posts: 2,436
    edited 2006-05-27 13:40
    Using a 7805 sounds rather wasteful to me. It's not exactly the most efficient regulator on the market.
    (go for a step-down switching one instead. )

    I haven't tried running anything with these batteries, but I have tried to run a BS1 on a single 3V CR1225, and that worked OK (you need to disable the brownout chip, and cross your fingers and hope the EEPROM likes it, but other than that... smile.gif

    I think the CR2032(very common as backup-battery on Motherboards, miniature radios, even LED flashlights) is rated at about 50 or 80mA. Take two of those and a good regulator, and you're all set, unless you NEED 12V.

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  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-05-27 16:43
    Consider a low droput regulator for a 6 volt battery.
    Consider a switcher regulator for higher effiency [noparse][[/noparse]wastes a mere 20%]
    Or consider a 1 amp series diode and no regulator for maximum battery juice.
    Why so?

    A 7805 quits at lower than 7 volts and 30% of the power is wasted in regulation as heat.

    You really don't need a voltage regulator on a battery supply as there is no noise from the origin and there is only one direction of variation - lower voltage.

    The diode will drop the voltage .6 to .7 volts [noparse][[/noparse]which will get you into a safe operating range] and likely waste the same or less than a regulator. You can do the math by figureing the load and the voltage drop.

    Additionally, the diode will protect you from reversed connection mistakes.

    I suspect just simple division 6volts/0.6 volts gives you a correct figure of merely 10% waste [noparse][[/noparse]but creeping higher as the battery goes down].

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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
  • pjvpjv Posts: 1,903
    edited 2006-05-27 19:22
    Kramer......

    Here you go leading folks down the wrong path.... again.

    The battery being proposed (A23) is a small 12V 80 mAH unit to power a 5 Volt application. Of course some form of voltage dropping is required, and it has nothing to do with "no noise". It is required to provide the specified 5 Volts over a (presumaby) variable range of currents.

    Your suggestion of using a low drop out regulator is totally bogus. The battery is deemed "dead" when its voltage falls to the input cutoff range of a "normal" 78XX regulator, so a low drop-out might squeeze only the last few percent out as the dead battery finally drops from 7 to 6 volts. Better to find a regulator that has a low self-energization current. In this low power case that will help a lot more.

    A switching regulator has the POTENTIAL of using the battery's energy more efficiently, but for low power applications the saving is very nominal. They really shine when consumption is more than several watts. Clearly not the case in this situation when one starts with only an 80 mAH source.

    And your suggestion of a 1 Amp diode????? ..... I think YOU need to do the math! The series diode approch will likely "blow" the Stamp. And furthermore, the power waste produced in non-switching regulators is the same, no matter how you achieve it; not your suggested 10%.

    Please, think about your answers before you post them, and if you're not positive of their correctness, don't guess..... that only confuses the situation, and only detracts from the quality of these forums.

    Sorry to beat up on you this way, but you've been given these recommendations before. You just don't seem to learn!

    Cheers,

    Peter (pjv)
  • SteveWSteveW Posts: 246
    edited 2006-05-27 21:08
    For what it's worth, those tiny 12V batteries are one of the most expensive, inefficient and generally painful ways of getting power on the planet. You're paying lots (both money and capacity) for the convenience of 12V, and, if you don't absolutely, positively, really need 12V, there's no excuse. They only get used in car immobiliser fobs because they can stick the customer with the battery replacement costs, and the current loadings are very, very low - zero, unless you press the button, which you do for a coulpe of seconds a day.
    If you want 5V, then an AAA cell and a little stepup switcher, like, say, LTC3400 from http://www.linear.com
    (there are others, I imagine, from Maxim and the like) is a far better solution. You'll pay for the silicon the first time you replace the battery. If you've got space for an AA cell, then the costs plummet further, and you'll be changing batteries much less often.
    (And, whatever else you do, don't use 7805 if you care about battery life. There are far better alternatives - look for the word 'micropower' in the datasheet. There's no point in throwing current away on a voltage regulator. 7805 is cheap- it has no other redeeming features)

    Steve
  • SteveWSteveW Posts: 246
    edited 2006-05-27 21:11
    Another low power comment - TIP120?!?!?! Noooo... If you want the battery to last, you don't want base current. MOSFETs are well worth investigating, if you want to turn loads on and off, that aren't powered by your battery. If your loads _are_ powered by your battery, and really need the brute force of a TIP120, then I fear your battery needs to be much, much bigger than you're suggesting.

    Steve
  • Robert@HCCRobert@HCC Posts: 80
    edited 2006-05-28 03:13
    The learning never stops turn.gif

    But I guess that is why I make this forum my first and last stop whenever I am on the Inet!

    Thanks for that reference to components like the LTC3400, thats pretty cool Steve ,3.3v out of a single AA . I was mainly looking at the A23 because of its small size, but if I can get 3.3 and 5v ( to supply my GPS and stamp) out of a couple AA OR AAA'S, I can fit those in to my package. Was thinking that I would need the AA in multiples (4+) and could never fit that many.

    I often hesitate to post here, since my knowledge is still quite limited. But in cases likes this, I am glad I do , as I learn so much!

    Alohas,
    Robert
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-05-28 12:40
    pjv,

    MikeK mentioned above that it was 6 volts which was the basis of my reply. It certainly wasn't my intention to lead someone astray.·

    I admire and respect your expertise as you are exceptionally knowledgible.· In any event, I really am not holding any ill will.· I do admit that I get over-enthusiastic.




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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

    Post Edited (Kramer) : 5/28/2006 3:15:00 PM GMT
  • pjvpjv Posts: 1,903
    edited 2006-05-28 17:26
    Hi Kramer;

    My intention was not to create any ill-will. I'm just suggesting you thoroughly think your answers through before posting. It almost appears as if you have a contest with yourself to post a reply to every question posed, and often not much is added by that contribution. What particularly bothers me is when those posts offer up incorrect information, either by your inexperience or by inadequate homework. If you're not positive of an answer, it may be best to remain silent.

    In this particular case Mike's comment referred to the mAH capacity before the voltage dropped from 12 to 6 Volts.

    Please, I embrace all contributions that further the discussions and open new ideas; they are a great learning tool for those who wish to heed the advice of the more experienced "seniors".

    I encourage you to contiue to participate, and I will do what I can to help you along the way.

    Cheers,

    Peter (pjv)

    Post Edited (pjv) : 5/28/2006 5:29:39 PM GMT
  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-05-30 15:02
    Evergreen, stay away from the small 12V batteries. Another member thought they'd be good to drive some incadescent lights for a small project and the battery died after a few seconds. Batteries like most things in life are a tradeoff, the tradeoffs in batteries are: size, voltage and capacity. The 12V batteries you are thinking of using maximize the first two (by maximize size, I really mean smaller), by sacrificing the third. If you don't need the 12V, stay away from it, go with 6V, 7.2V or 9V, because the overhead is just a waste.

    What of the three criteria is important to you? IOW how small of a space do you need to fit it in, how frequently are you willing to replace the batteries, and what is the minimum voltage needed for your project?

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  • evergreenevergreen Posts: 43
    edited 2006-05-31 05:34
    Paul,

    I just need the batteries to be small and light (I'd like for them to fit onto a 2" wide board). Disposable batteries would probably be easiest. The batteries would be powering a BSII module, an A/D, a Motarola barometer, and 3 transistors (TIP120). The microcontroller would be turned on in 60 second periods, meaning I'd be able to change the batteries every 60 seconds (if need be). Two of the transistors would go high once during the 60 second period, and would be connected to an external 9v battery. The third transistor would also be hooked up to that external battery, and would go high and low every 1 second for about 30 seconds of the 60 second period.

    Any suggestions would be awesome.

    Thanks!
  • GadgetmanGadgetman Posts: 2,436
    edited 2006-05-31 06:41
    Stick in a couple of 'button' type cells, like the CR43/44 LR43/44 cells used in laserpointers.

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  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-05-31 15:07
    Are those type 1.5 or 3V? If its 1.5, 4 would be needed.

    So you're doing a rocket telemetry project?

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  • PJAllenPJAllen Banned Posts: 5,065
    edited 2006-05-31 15:26
    evergreen said...
    meaning I'd be able to change the batteries every 60 seconds (if need be).

    · Will there be a webcam or a video of this?
  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-05-31 15:38
    What kind of load are you using with the 9V? if it isn't extreme, you may be able to use the 9V battery as well.
    Or if the 9V drops out too much from the load when the transistors are on, you could perhaps use 3 of these in series, these are really just capacitors capable of holding alot of charge, you could employ a switch to charge them from the 9V, then switch it back so they supply the electronics, the charge should be able to last long enough for what you need.

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  • evergreenevergreen Posts: 43
    edited 2006-06-03 21:03
    Sorry for the long delay!

    The batteries will release about 1 amps for 2 seconds (maybe closer to 1 second).

    You're right about the rockets, but no telemetry. Just firing off ejection charges (e-matches).

    What do you mean about the video? By every 60 seconds, I really meant that I could switch out the batteries in between launches.

    Thanks again!
  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-06-05 15:30
    Gotcha, for most battery chemistries that current is beyond thier design. Since you'll be using 9V battery, this would almost assuredly drop·the voltage·too low for your electronics to be happy. I would either go with the capacitors I showed in the previous link or use a couple of these in series: http://www.sparkfun.com/commerce/product_info.php?products_id=731

    You could go with button cell batteries, but they can get expensive to replace. Using the capacitors, you only take a bit of charge off the 9V battery. If you go with sparkfun's batteries·you get a Li-ion charger·and you can use·batteries over and over (and likely use them a few times before needing to recharge them).

    Sparkfun has a cool new Li-ion charger: http://www.sparkfun.com/commerce/product_info.php?products_id=726

    which you can use a wall wart, or a USB port to charge a li-ion battery, very handy if you already have a laptop in the field with you.

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    Post Edited (Paul Baker) : 6/5/2006 3:34:26 PM GMT
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