Low battery indicator
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Posts: 46,084
Hi All
From most battery operated devices we see a low battery indicator, no matter
it is in the form of LED or LCD display.
I just wonder if they implement this "small-simple-good" feature by direct
measuring the battery voltage and do a comparison, or what? Can we implement
the same function by a stamp? If it is a voltage measurement, stamp surely
can handle that.
Anybody has some idea?
John
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From most battery operated devices we see a low battery indicator, no matter
it is in the form of LED or LCD display.
I just wonder if they implement this "small-simple-good" feature by direct
measuring the battery voltage and do a comparison, or what? Can we implement
the same function by a stamp? If it is a voltage measurement, stamp surely
can handle that.
Anybody has some idea?
John
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
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Comments
Create a voltage divider with a high value pot. (Insure the wiper is
set at 5V or less) Take the pot wiper and feed to the Stamp RCTIME
preferred circuit. Readings will be proportional to the voltage.
Don
John Leung wrote:
>
> Hi All
>
> >From most battery operated devices we see a low battery indicator, no matter
> it is in the form of LED or LCD display.
>
> I just wonder if they implement this "small-simple-good" feature by direct
> measuring the battery voltage and do a comparison, or what? Can we implement
> the same function by a stamp? If it is a voltage measurement, stamp surely
> can handle that.
>
> Anybody has some idea?
>
> John
>
> ---
> Outgoing mail is certified Virus Free.
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Thanks a lot. Do you mean the common way of telling battery level is to
measure the voltage directly?
John
Original Message
From: "Don Denhardt" <dondenhardt@y...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, December 16, 2001 4:39 PM
Subject: Re: [noparse][[/noparse]basicstamps] Low battery indicator
> Hi John
>
> Create a voltage divider with a high value pot. (Insure the wiper is
> set at 5V or less) Take the pot wiper and feed to the Stamp RCTIME
> preferred circuit. Readings will be proportional to the voltage.
>
> Don
>
> John Leung wrote:
> >
> > Hi All
> >
> > >From most battery operated devices we see a low battery indicator, no
matter
> > it is in the form of LED or LCD display.
> >
> > I just wonder if they implement this "small-simple-good" feature by
direct
> > measuring the battery voltage and do a comparison, or what? Can we
implement
> > the same function by a stamp? If it is a voltage measurement, stamp
surely
> > can handle that.
> >
> > Anybody has some idea?
> >
> > John
> >
> > ---
> > Outgoing mail is certified Virus Free.
> > Checked by AVG anti-virus system (http://www.grisoft.com).
> > Version: 6.0.295 / Virus Database: 159 - Release Date: 11/1/01
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
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and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
>
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>
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Uses one acd0831 analog to digital converter with a very short
program.
Use a high value bleeder network like unknown voltage to 100k to 10k
to ground. Read at tap between 100k and 10k. Use a extenal digital
voltmeter to calibrate at a low end and high end point.
If you use a regulator to provide the reference to the adc you can get
precision readings from this.
73
spence
k4kep
LM339, a stable voltage reference such as TI TL431 and a voltage
divider.
The LM339 has an open collector so could be interfaced directly to
Stamp.
Another advantage is that you can add histerysis to prevent chatter
when the battery level crosses the threshold.
Albert Catano
--- In basicstamps@y..., "k4kep" <k4kep@y...> wrote:
> BOOK STAMP WORKS EXPEREMENT 27 ON PAGE 29.
> USES ONE ACD0831 ANALOG TO DIGITAL CONVERTER WITH A VERY SHORT
> PROGRAM.
>
> USE A HIGH VALUE BLEEDER NETWORK LIKE UNKNOWN VOLTAGE TO 100K TO
10K
> TO GROUND. READ AT TAP BETWEEN 100K AND 10K. USE A EXTENAL DIGITAL
> VOLTMETER TO CALIBRATE AT A LOW END AND HIGH END POINT.
>
> IF YOU USE A REGULATOR TO PROVIDE THE REFERENCE TO THE ADC YOU CAN
GET
> PRECISION READINGS FROM THIS.
>
> 73
> SPENCE
> K4KEP
Yes whether being charged or under load, battery voltage is used for
status of the battery.
At this link there is a ton of information regarding batteries (more
than you probably want to know). There is a chart that will roughly
plot battery state of charge by voltage.
http://www.windsun.com/Batteries/Battery_FAQ.htm
When dealing with flooded cells you have to remember that there will be
some variance in these readings owing to the electrolyte blend being
used and plate chemistry.
Good luck,
Don
John Leung wrote:
>
> Hi Don
>
> Thanks a lot. Do you mean the common way of telling battery level is to
> measure the voltage directly?
>
> John
>
>
Original Message
> From: "Don Denhardt" <dondenhardt@y...>
> To: <basicstamps@yahoogroups.com>
> Sent: Sunday, December 16, 2001 4:39 PM
> Subject: Re: [noparse][[/noparse]basicstamps] Low battery indicator
>
> > Hi John
> >
> > Create a voltage divider with a high value pot. (Insure the wiper is
> > set at 5V or less) Take the pot wiper and feed to the Stamp RCTIME
> > preferred circuit. Readings will be proportional to the voltage.
> >
> > Don
> >
> > John Leung wrote:
> > >
> > > Hi All
> > >
> > > >From most battery operated devices we see a low battery indicator, no
> matter
> > > it is in the form of LED or LCD display.
> > >
> > > I just wonder if they implement this "small-simple-good" feature by
> direct
> > > measuring the battery voltage and do a comparison, or what? Can we
> implement
> > > the same function by a stamp? If it is a voltage measurement, stamp
> surely
> > > can handle that.
> > >
> > > Anybody has some idea?
> > >
> > > John
> > >
> > > ---
> > > Outgoing mail is certified Virus Free.
> > > Checked by AVG anti-virus system (http://www.grisoft.com).
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> > >
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> and Body of the message will be ignored.
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> >
>
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>Thanks for all valuable information. I will try.
Just beware that when you do your calculations to convert your reading to
the true voltage, that a divider consisting of a 100K and a 10K resistor is
an 11:1 divider.
Jim H
John
Original Message
From: "acatano2002" <acatano2002@y...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, December 16, 2001 8:58 AM
Subject: [noparse][[/noparse]basicstamps] Re: LOW BATTERY INDICATOR
> If you want something more foolprof, a voltage comparator such as a
> LM339, a stable voltage reference such as TI TL431 and a voltage
> divider.
> The LM339 has an open collector so could be interfaced directly to
> Stamp.
> Another advantage is that you can add histerysis to prevent chatter
> when the battery level crosses the threshold.
>
> Albert Catano
>
> --- In basicstamps@y..., "k4kep" <k4kep@y...> wrote:
> > BOOK STAMP WORKS EXPEREMENT 27 ON PAGE 29.
> > USES ONE ACD0831 ANALOG TO DIGITAL CONVERTER WITH A VERY SHORT
> > PROGRAM.
> >
> > USE A HIGH VALUE BLEEDER NETWORK LIKE UNKNOWN VOLTAGE TO 100K TO
> 10K
> > TO GROUND. READ AT TAP BETWEEN 100K AND 10K. USE A EXTENAL DIGITAL
> > VOLTMETER TO CALIBRATE AT A LOW END AND HIGH END POINT.
> >
> > IF YOU USE A REGULATOR TO PROVIDE THE REFERENCE TO THE ADC YOU CAN
> GET
> > PRECISION READINGS FROM THIS.
> >
> > 73
> > SPENCE
> > K4KEP
>
>
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>