2. The Device
On request we can supply custom product variants with special housings powered by even
bigger batteries. For example a 3.6V C sized mono cell typically has a capacity of 9Ah with
leads to a 3x increased battery life compared to the standard AA-cells. With D sized cells of
typically 19Ah capacity this value can be doubled once again (6x). Also available on request
are options with permanent external power supply (230V, 9-24V, 5V USB).
2.3. Battery life time
The battery life time of the wireless M-Bus to LoRaWAN Bridge can not be specifed trust-
worthy without knowledge of the detailed installation scenario. At least estimations for the
following custom project based parameters have to be known:
Meter count per single wMBUS bridge, e.g. 10 dierent meters.
Needed LoRaWAN transmission interval, e.g. daily uploads.
Average wireless M-Bus telegram size in bytes, e.g. 35 byte.
Wireless M-Bus telegram transmission interval of the meter, e.g. every 10 seconds.
Typically used LoRa Spreading Factor / LoRa link quality, e.g. SF10.
Depending on these parameters battery life times from a few months to over 15 years can
be achieved. You may send us your use-case details as described above to
and we will return to you a custom battery lifetime calculation, a recommendation for the
best power supply scheme and the needed minimal battery capacity.
2.3.1. Example calculation
In this battery lifetime calculation scenario the target meters send a 35 byte long (`L-Field')
wireless M-Bus telegram constantly every 10 seconds. This behavior is for example very
similar to a `Hydrus' ultrasonic water meter of Diehl Metering
. The Diehl meter itself has a
specied battery life time of 12 years.
Because of the mentioned 10 second send interval it is sucient to congure the bridge for
a wireless M-Bus listen period of 20 seconds by setting the bridge conguration parameter
cmodeDurSec to a value of 20 (refer to section 4.3.2). This will ensure that all meters of
interest sent their consumption telegrams at least onces during the congured listen period
of the bridge.
For a worst-case battery-lifetime calculation the weakest possible LoRaWAN connectivity has
been selected. That means to reach a LoRaWAN Gateway the Lobaro hardware has to send
out its Uplink data very slowly ( 2 seconds) and redundant by using a LoRa spreading factor
of 12. Beside this the actual usable battery capacity has been set to 80% of the nominal
value. The resulting worst-case minimal battery-life times are presented in table 1.
https://www.diehl.com/metering/
wMBUS over LoRaWAN Bridge
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