Battery Service Life; Batteries: Estimating The Working Life - Siemens Simatic RTU303xC Series Operating Instructions Manual

Configuration (WBM)
4.18 Operating mode
4.18.4

Battery service life

Remaining battery capacity
In this tab (HW2), the calculated remaining capacity of the batteries, the consumption since
the last activation and the theoretical remaining value are indicated. This calculation should
help to better estimate electricity consumption.
Exact calculation of the remaining capacity of the battery is not possible since this depends
on numerous factors, for example, the connected consumers, changing outdoor
temperatures and, above all, the frequency of configured events such as limits of measured
values being exceeded.
Battery capacity
● Battery module 1/2
Calculated capacity of the respective module. The capacity of the battery decreases due
to self-discharge, current consumption at low temperatures and high current peaks.
These effects are determined separately for the respective battery module and offset
against the nominal capacity of the batteries.
● Consumption since last activation
Shows the measured consumption since the last activation of the currently used module.
● Total remaining capacity
Displays the calculated capacity. The value results from the sum of the battery capacity
over all connected battery modules minus the consumption since the last activation.
The remaining capacity is available as a variable BAT_RES_CHARGE in the user
program.
Logging
● Remaining capacity
Using the drop-down list, you can enable logging of the value of the calculated remaining
capacity.
4.18.5

Batteries: Estimating the working life

Working life of the batteries
The power consumption of the RTU depends on many factors, the connected consumers,
changing outdoor temperatures and above all on the frequency of configured events such as
limits of measured values being exceeded. A precise calculation of the power consumption
of the RTU is therefore not possible.
To estimate the power consumption of the RTU, you can list the frequency of the individual
operating modes expected by you or configured and derive a rough value for the daily power
consumption of the RTU from the specific consumptions.
You will find the electrical data in the section Technical data (Page 335).
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Operating Instructions, 06/2019, C79000-G8976-C382-06
RTU303xC