You can of course set up a resistor in series with the mote
and measure the voltage drop with another ADC channel. This
will tell you the current draw....but won't be much use in
predicting the battery power left unless you use it to
accumulate the life-time power used and have a good estimate
of the original charge.
Comparing the battery voltages at some large current draw
over time will give you a good idea of bat power available, but
for the most part it won't be any more predictive than just
watching the batvoltage itself. At some point it should start
to drop (more) precipitously, and that means the battery
is dying...
Depending on the battery type and age, some fixed voltage
threshold should give you a good rule-of-thumb end-of-life
indication.
MS
Venkat Ram wrote:
------------------------------
Message: 6
Date: Wed, 18 Jan 2006 17:30:57 +0800
From: Bright Xu < [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>>
Subject: [Tinyos-help] how to let a mote predict how much battery
power left?
To: [email protected]
<mailto:[email protected]>
Message-ID: <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
By using TinyOS component "VoltageM.nc", A mote can read value of
battery voltage. But how to gain value of current? how to let a mote
predict how much battery power left? Thanks.
------------------------------
You cannot get the current value directly from the motes but measure
voltage readings which is available. You can however use a multimeter to
measure the current when the motes are in operation.
Another alternative is to run them in a simulator which
returns current measure.
-karthik
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