DAVIS Cellular Telephone Antenna Kit - Manual (Page 23)

Charge Budget Page 23
C HARGE B UDGET
When using the CTM in a solar/battery-powered station, one must limit the
power drawn by the CTM. The means limiting the time that the CTM is on,
enabled to receive calls, and limiting even more severely the duration of calls.
The worksheets below enable you to calculate the charge drain per day and the
charge gain per day (from the solar panel). Comparison of these two numbers
will give you an idea of how long you may use the CTM before draining the
power supplied by the solar panel.
Charge Drain per Day
The worksheet below enables you to calculate the charge drain per day for var-
ious power on and transmission times.
For each system component, write the amount of current drawn (in Amps) in
the Current column and the number of minutes per day the component is “on”
in the Time On column. Multiply the current drawn by the number of minutes
to determine the drain caused by that component each day. Add the individual
drain figures together to determine the total drain per day for the entire system.
Consult the following for an explanation of worksheet lines A, B, C, and D.
✦ Line A (Console, SIM/junction box & WeatherLink)
The Weather Monitor II, with junction box and WeatherLink, draws 16
mA (0.016A) continuously (1440 minutes per day). The GroWeather,
Energy EnviroMonitor, and Health EnviroMonitor, with sensor interface
module (SIM) and WeatherLink, draw 20 mA (0.020A) continuously
(1440 minutes per day).
✦ Line B (Alarm Output Module/Timer)
The Alarm Output Module draws 9 mA (0.009A) continuously (1440
minutes per day). The Timer current may be considered negligible (0)
when the Timer is off (that is, its relay is not energized). The Timer draws
12 mA (0.012A) when it is on (that is, the relay is closed).
✦ Line C (CTM On)
When the CTM is on (enabled), it draws 350 mA (0.35A).
Note: The Alarm Output Module enables the CTM for a minimum of 48 minutes every day (4
minutes each even-numbered hour). The timer enables the CTM for the amount of time
for which you have it set.
C OMPONENT C URRENT T IME O N D RAIN L INE
(A MPS ) ( MIN / DAY ) (A MP - MIN )
Console, SIM/junction box & WeatherLink ______ 1440 ______ A
Alarm Output Module/Timer ______ ______ ______ B
CTM On 0.350 ______ ______ C
CTM Transmitting 1.300 ______ ______ D
Total System Drain per Day = A+B+C+D: ______ Amp-min