User manual
905K Radio Telemetry Module User Manual
ELPRO Technologies Pty Ltd 2010 Page 30
Operation of the 905K will stop during battery change, however
configuration of the module will not be lost when batteries are
removed, so no special procedure is required when changing
batteries of the same type.
Batteries should be inserted as per the drawing - with the BU-5
aligned such that the cable comes out of the top of the module.
The BU-5 can be mounted in any direction. The enclosure lid can
be rotated.
CAUTION!!
LITHIUM Batteries must not be
used when modules are installed in
a hazardous area
3.4.3 External Battery Supplies
An external battery supply can be used. The self discharge of the battery must be considered, as
often this can be more than the power consumption of the 905K. For example, most
rechargeable batteries only have a shelf life of 12 months - that is, with nothing connected to
the battery, the battery will self discharge in 12 months.
An example of an external battery supply is two Energizer Alkaline 528 batteries in series. Each
battery is 6V 26 amphour - two in series gives 12V 26 amphour. The combined battery voltage
will drop from 12V to 8V before it is discharged, but this is adequate as the 905K can accept
supply down to 6V. The shelf life of these batteries is in excess of 5 years and will operate from
0 – 130 degF (-10 to 55 degC).
The use of this type of battery will require an external enclosure, however will provide a much
longer life than the BU-5 battery pack. For example, this type of battery supply will last more
than 4 years for a 905K with an analog input, sampled every 5 minutes for 3 seconds.
The 905K provides a configurable low voltage alarm for early warning of battery failure. It
should be set above the low voltage limit for the particular battery. For the example discussed,
the low alarm could be set at 8.4V - the battery will still operate for a long period of time after
the alarm is transmitted.
Ensure that the connection between the battery supply and the 905K is protected by an in-line
fuse rated at no more than 2 amp.
3.5 Input Signal Connections
3.5.1 Digital/Pulse Inputs
Digital and pulse inputs share the same input channel. Each input is connected between the DIN
connector and COMMON. Inputs can be voltage-free contacts, NPN transistor switches, or a
TTL voltage signal (ON < 1.5 volt DC, OFF > 3.5 volts DC).