User Manual

Global Water Instrumentation
10
hours. Sy stem s that require access to inter r ogation and control should have power
system s des igned ac c or ding to the requirements of the syst em. The voltage
thresholds for the diff erent power m odes ar e as follows:
Battery Voltage >= 12.8 volts; Battery Charging. The battery has sufficient charge
and the radio remains on all of t he time to receive commands .
12.0 volts < Battery Voltage < 12.8 volts; Low battery. R adio remains on only
when data is being t r ans m itted.
11.3 volts < Battery Vol t age < 12.0 volts; Very Low Battery. Radio remains on
only when data is being transmitt ed. The SV LED blinks every 5 s ec onds
Battery Voltage <= 11.3 volts; Dead battery. All operations s top and the radio
remains shut off until the battery recharges again.
Battery Voltage Monit or
The SIT65 of fers a full time batter y v oltage monitor that report s s yst em voltage
automatic ally with every tr ans m is s ion. This is a very important t ool for checking the
installation, syst em c omponents , solar panels and battery. It should be watched
carefully when the system is f ir st ins talled and periodically from then on. Downward
trends t hat seem abnormal may be an indicat or that something is wrong. Sudden
changes in operation may be caused by environmental changes, an electrical
problem that is dr awing ex c es s iv e c ur r ent, or a problem with the c har ging s y s tem. A
slowly dropping volt age may indicat e that the battery is losing its capacity and needs
to be replaced. Ot her signs of this are that the problem will likely occur when going
into fall or winter, and that the s iz e of t he v ol tage fluctuations f r om day to night w ill be
larger than norm al.
Solar Power Systems
The SIT65 sy s tems are especially suited for v er y r emote locations where solar
power is the only option. Solar powered sy st em s r equir e a very good understanding
of the application and system r equir ements. Some systems need to be powered
reliably all of t he time and some can be shut down during the entire winter.
Availabilit y of interrogation and contr ol, transmission intervals, alarm transmissions,
the number of s ens or s connect ed, and many other factors must be evaluated. Most
important ly ; seasonal changes and geographical factors like cloud cover,
temperature, snow, dust and how high t he s un is in the sky can change solar s y s tem
efficienc y . No attempt is made here t o dis c us s all of t he factors in solar s y s tem
design.