Data Delivery Devices RFScada 2DI-4DO Long Range Spread Spectrum Bi-Directional Wireless Telemetry Unit User Manual

							RFScada User Manual Version 1.7 Copyright ©2002 Data Delivery Devices LLC   Page - 31 – 120 NE DeBell Suite B Bartlesville OK 74006      Tel 918-335-3318      FAX 918-335-3328 
 
Solar Panel Operation 
I understand that the RFScada has a 12 Volt rechargeable battery inside the case. Can 
I just connect a 12 volt solar panel directly to the internal battery and operate the unit 
without AC power? 
No. The internal battery has enough capacity (1.2 Amp/Hr) to operate the unit for at 
least 6 hours, but probably no longer than 10 hours, so it would not have enough 
capacity to operate the unit through the night even if fully charged. Also, many of the 
small, very basic solar panels have no ‘charge control’ to prevent overcharging the 
battery so damage could result. The very small ‘trickle’ type solar panels do not have a 
high enough output to operate the unit. However, the RFScada may easily be operated 
from a solar panel if suitable components are used.  
First of all a panel must be selected that can supply at least three or four times the 
energy required to operate the RFScada (approximately one to two watts), since the 
panel must both supply the unit and be capable of charging the battery in the shortest 
daylight available, even on a cloudy day. A system using a panel having a nominal 10 or 
20 watts output should have an ample safety margin. Secondly a battery must be 
selected that will be able to hold enough energy to operate the RFScada for a period of 
time, plus the battery must be able to withstand the sometimes fairly heavy charging 
and discharge cycle. Small auto or marine ‘deep cycle’ type batteries are most 
commonly used, as they are universally available at a very reasonable cost. Finally, as 
mentioned earlier it is possible to damage batteries by overcharging them, so some type 
of charge controller is normally required. Some solar panels have the charge controller 
already built in, if that type of panel is used another controller is not needed.  
The components required will vary depending on the location, for example Alaska in 
winter has very little daylight available, so a solar system there would need much 
greater capacity than one located in Arizona. It is usually possible to connect the 
RFScada directly to an existing 12 Volt solar power system that is being used to power 
other equipment such as RTU’s or transducers, simply connect the external source to 
the 12V DC input (J2 pins 1 and 2). The internal backup battery is charged via a charge 
controller built into the RFScada unit and is not connected directly to the 12Volt DC 
input, so it will not be damaged by a fluctuating DC voltage being supplied to the 
RFScada 12Volt DC (J2) input. Do not attempt to connect an external 12 Volt source to 
the 12 Volt backup battery or the battery connector (J6) in the RFScada unit.  
 
Cabinet Construction 
The brochure states that the RFScada has a corrosion resistant NEMA 4X rated cabinet 
but the antenna is located inside. Doesn’t the stainless steel cabinet severely restrict the 
unit’s range? 
No, the corrosion resistant NEMA 4X rated cabinet is not stainless steel but made 
from fiberglass with stainless steel fittings (hinge, locking latch etc.) so it has very little 
effect on the signal.      
 
Mounting Inside Steel Enclosure 
If the unit is mounted inside a steel electrical switchboard will the range be affected? 
Yes, the range will be reduced if it is mounted inside a steel enclosure. Whether 
the attenuation will be enough to prevent operation will depend on the cabinet, distance 
to the other unit and all the other factors that affect range.