Battery Status

Archiver

Stampers
I am looking for an easy way for the Stamps 2 to check the battery status of
a 12 volt battery. Any ideas?

Thank you

Archiver

At 06:54 AM 3/15/00 -0500, you wrote:

>I am looking for an easy way for the Stamps 2 to check the battery status of
>a 12 volt battery. Any ideas?

I just did an app. that had to monitor a 12 to 36v power supply with a
MAX187 12bit serial ADC. This thing worked great, and there's code
available for a BSII. Get the chip and the datasheet at:

http://www.maxim-ic.com

Get the code at:

http://www.hth.com/filelibrary/BS2-IC/

There's two versions of the code here, each slightly different. To measure
12V, you'll have to use a voltage divider to the ADC. If you don't know
what that is, there's a nifty online (java) calculator at:

http://www.woodsbas.demon.co.uk/calcs/vdivide.htm

Best, Duncan

Archiver

The simplest way is usea a series resistor divider and check if battery is
above or bellow a determined limit.
(10 v for example.) A pin have a treshhold about 1.4 volt. Other available
pins may be used to check other
limits.
ACJacques.

Trkeenan@a... wrote:

> Stampers
> I am looking for an easy way for the Stamps 2 to check the battery status of
> a 12 volt battery. Any ideas?
>
> Thank you
>
>

---

> -- Easily schedule meetings and events using the group calendar!
> -- http://www.egroups.com/cal?listname=basicstamps&m=1

Archiver

> I am looking for an easy way for the Stamps 2 to check the
> battery status of a 12 volt battery. Any ideas?


RCtime can do this.
http://www.emesystems.com/BS2misc.htm#RCtime

470 ohm 100 kohm
P0 ----/\/\/\---o

---

/\/\/\----Vx unknown voltage
|
===== 0.1 uF film
|
Vss

And the BS2 test program is:

tx var word ' RCtime value
vx var word ' voltage value to be determined
Cn1 con 65000 ' first constant
Cn2 con 14 ' second constant
low 0
loop:
RCtime 0,0,tx
low 0
vx=Cn1 / tx - Cn2 / 2
debug home,dec? tx,"vx=",dec vx/10,".",dec1 vx
pause 1000
next

To calibrate, put a known voltage (say 12.6 volts) input at Vx an see what
answer you get out. Adjust the proportionality constant Cn1 to make it
come out right. Then put in a lower voltage (say 6.4 volts), and this time
adjust Cn2. Repeat for desired accuracy. It is accurate over a narrow
range of voltages typical of batteries in normal use.

-- Tracy Allen
Electronically Monitored Ecosystems
http://www.emesystems.com

Archiver

Trkeenan@a... wrote:
>I am looking for an easy way for the Stamps 2 to check the battery status
of
>a 12 volt battery. Any ideas?

I needed such a critter and found a MAX666 from Maxim. I needed a device to
monitor a 12V gel cell and turn on a LED when it's voltage dropped to 10.5
volts. The 666 can do this. The indicating voltage is user settable. I have
the Maxim data sheet in .PDF format if you cannot find it on Maxim's web
site:

www.maxim-ic.com

Contact me OFF-LIST if you need the data sheet. Don't clog up the list with
requests.

Hope this helps.

Vic
_________________________________________

Victor Fraenckel vfraenc1@n...
Home of the WindReader Electronic Theodolite
Read the WIND

Archiver

You can use an voltage comparator. I can explain how to do this if you
e-mail me back.

Derek


>Trkeenan@a... wrote:
>>I am looking for an easy way for the Stamps 2 to check the battery status
>of
>>a 12 volt battery. Any ideas?
>
>

Archiver

Thanks for all the ideas
tim

Archiver

In a message dated 03/15/2000 9:11:14 AM Mountain Standard Time,
emesys@c... writes:

<< > I am looking for an easy way for the Stamps 2 to check the
> battery status of a 12 volt battery. Any ideas?


RCtime can do this.
http://www.emesystems.com/BS2misc.htm#RCtime
>>
Nice web page. Thanks for your help. The battery monitor idea worked real
well.

Tim