Monitoring Battery Power Level

joelman

How would I monitor the power level of my 9V battery using the Basic Stamp? I basically want to keep track of how much more life is in my battery.

Bruce Bates

joelman -

Other than checking the voltage with a voltmeter before you use it, little else makes much practical sense, since 9 volt batteries have such poor power reserve. With larger or different batteries, and/or with rechargables, a battery monitoring system would be worth the investment in money and time.

Just one opinion.

Regards,

Bruce Bates

Tracy Allen

There's an app note on using RCTIME to monitor the Vin battery supply, at this URL
emesys.com/BS2rct.htm#B_voltage
Bruce, a 9 volt battery at 300 milliamp hour can last quite a long time in a project, especially if the Stamp can SLEEP, perchance dream.

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Tracy Allen
www.emesystems.com

Post Edited (Tracy Allen) : 10/30/2005 7:11:30 PM GMT

joelman

Sweet.

Thanks,
Joel

Tricky Nekro

The best way is by using a 555 timer...
Here's schematic and program...




' {$STAMP BS2}
' {$PBASIC 2.5}
' First started by TronicGR, later modified by Provas.
' For www.Greekbotics.tk

'Variables
coefficient·· VAR·· Word···· 'AD555 math var
adc555······· VAR·· Word···· 'AD555 input values
result······· VAR·· Word···· 'AD555 calculated float-point output
volts········ VAR·· Word···· 'AD555 true integer output
LED·········· CON·· 1


DO

·· PULSIN 2, 1, adc555········
' DEBUG DEC adc555, CR····

coefficient = 27499······
volts = coefficient / adc555
result = volts *100······
volts = adc555 * volts···
coefficient = coefficient - volts * 10
volts = coefficient / adc555
result = volts * 10 + result
volts = adc555 * volts
coefficient = coefficient - volts * 10
volts = coefficient / adc555
result = volts + result
result = result + 250

·····················
·· DEBUG CLS, DEC result," = volts * 100",CR
·· IF (result < 800) THEN blink_Led
·RETURN······································
LOOP


blink_Led:
HIGH LED
PAUSE 100
LOW LED
PAUSE 100
RETURN


Greece, Provas

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-Rule your Destiny-
--Be Good. Be Bad. Be Provas--


Post Edited (Provas) : 10/30/2005 6:53:00 PM GMT

Tricky Nekro

My application is precise and used for seperate volt supply...

I didn't try yours, but it sould be as fine as mine...

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Rule your Destiny-
--Be Good. Be Bad. Be Provas--

Chris Savage

I think, "Best Way" is a relative/subjective term which may apply differently depending on the given circuit/power/layout considerations.· I guess what I am saying is that we cannot offer the "best" solution, only possible solutions and the user has to decide what works best for him/her.


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Chris Savage
Parallax Tech Support
csavage@parallax.com

Tracy Allen

I found that spacing in the ascii art at emesys.com/BS2rct.htm#B_voltage had been thrown off somehow, so I just went in and corrected and republished it. Agreed, "best" is a relative term. In some cases, a simple "low battery" threshold detector is all that is required. At the otherr extreme, it has to be accurate to microvolts and only a high resolution ADC will do the trick.

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Tracy Allen
www.emesystems.com

steve_b

There was an article (not on this pc) that described using a lamp (@rated voltage) and a CDS photocell with RCtime.
The orginal use was in a solar panel system, so the user wanted to be sure to isolate the measuring device from the charging system....

They enclosed the lamp and the photocell in a 'dark' box and used a lookup table I think to determine voltage levels.

You could also use an A/D converter or if you just want to know when the voltage drops to a certain amount you could use a voltage divider that equates to a logic level....."many ways to skin a cat"

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·

Steve

"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."

Beau Schwabe

This subject came up recently in another thread....

Here is a link to a thread that I posted quite some time ago on the L.O.S.A. (List Of Stamp Applications)

http://forums.parallax.com/showthread.php?p=548418

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

sam_sam_sam

Hi Provas

And every one else

Please look at PM· Provas

I have to ask you something

Sam

Tricky Nekro

Sam

I've received the pm...

Please check yours, too...

I'll upoad some files, hoping to help you as·much as I can...





Friendly, Provas, Greece


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-Rule your Destiny-
--Be Good. Be Bad. Be Provas--


Post Edited (Provas) : 10/31/2005 10:17:23 PM GMT