[Tinyos-help] Battery (AA) life test results on MICA2 mote

Michael Newman mnewman at dragonnorth.com
Fri Jan 30 10:58:50 PST 2004


This analysis is anecdotal. I have not made careful measurements but here is
what I think is going on.

I think I see continued send operation for a long time (days) but the nodes
sleep a lot (minutes). The delta is probably better measured in volts.

I have not carefully measured the voltages but my gut feel is that I still
transmit from between one and two tenth volts lower voltage after I lose
reception. 

A bigger issue than absolute voltage is how much current you can draw out of
the battery. The usage pattern I have is that the node wakes up, calculates
and sends a message. Then it remains on for some number of seconds (approx
3) listening for an ACK and any instructions. The base station is listening
to the node. The base station does simple store and forward. When it hears
the node it will send the messages waiting for that node and then send the
ack. Since this system always sends prior to receiving current available
from the battery will be at a peak for sending and diminished for the
listening period that follows the send. This may or may not matter...




-----Original Message-----
From: Kristin Wright [mailto:kwright at cs.berkeley.edu] 
Sent: Friday, January 30, 2004 12:34 PM
To: 'Michael Newman'; 'YE, Fan'; jsuh at xbow.com
Cc: tinyos-help at today.cs.berkeley.edu
Subject: RE: [Tinyos-help] Battery (AA) life test results on MICA2 mote


What's the delta between the times? That is, the difference between the time
that receiving ability is lost and the time that sending ability is lost? Is
it on the order of days, hours or minutes?

-kw

> -----Original Message-----
> From: tinyos-help-bounces at Millennium.Berkeley.EDU [mailto:tinyos-help-
> bounces at Millennium.Berkeley.EDU] On Behalf Of Michael Newman
> Sent: Friday, January 30, 2004 10:00 AM
> To: 'YE, Fan'; jsuh at xbow.com
> Cc: tinyos-help at today.cs.berkeley.edu
> Subject: RE: [Tinyos-help] Battery (AA) life test results on MICA2 mote
> 
> One empirical observation, from my work on the Sensicast development kit.
> 
> The nodes lose the ability to receive first then the ability to transmit.
> This has implications for deciding when a node is alive. You can not
> simply
> monitor how long it sends out messages, you must know how long it can
> receive a message as well.
> 
> 
> 
> 
> 
> 
> 
> -----Original Message-----
> From: tinyos-help-bounces at Millennium.Berkeley.EDU
> [mailto:tinyos-help-bounces at Millennium.Berkeley.EDU] On Behalf Of YE, Fan
> Sent: Wednesday, January 28, 2004 5:10 PM
> To: jsuh at xbow.com
> Cc: tinyos-help at today.cs.berkeley.edu
> Subject: Re: [Tinyos-help] Battery (AA) life test results on MICA2 mote
> 
> John,
> 
> I'm curious about how you judged the "enf-of-service" moment. Was it
> continual loss of X packets at the reference mica2 or something else?
> Thanks,
> 
> Fan YE
> 
> On Wed, 28 Jan 2004 jsuh at xbow.com wrote:
> 
> > Crossbow has done an experiment to find out how long a MICA2 will work
> when
> > powered with two AA batteries.
> >
> > The experiment was to have motes programmed with the TinyOS (v 1.1.0)
> > application CntToLedsAndRfm, which transmitted a TOS packet once every
> four
> > seconds. A basestation 30 meters away monitored the radio signals. The
> tests
> > were run in an indoor, office environment.
> >
> > The tests showed that the motes lasted for 172 hours or more than 85% of
> the
> > rated capacity of the AA batteries. Furthermore, the MICA2 motes
> continued
> > to work until they reached about 2.1 V. When an 85% efficient battery
> > booster was used, the MICA2 motes continued to work for another 5 hours
> > (4%).
> >
> > More details on this experiment can be found at
> > http://www.xbow.com/Support/Support_pdf_files/MICA2_BatteryLifeTest.pdf
> > <javascript: void
> >
> window.open('http://www.xbow.com/Support/Support_pdf_files/MICA2_BatteryLi
> fe
> > Test.pdf', '_blank')> .
> >
> > Sincerely,
> > John Suh
> > Crossbow Technology, Inc.
> > 408-965-3300
> > http://www.xbow.com <http://www.xbow.com>
> >
> >
> >
> >
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