Version: 2020-09-04
166
Copyright of the European Union is effective (Copyright EU) (c) 2019 GENEREX Systems GmbH, Hamburg, Germany, All rights reserved
TEL +49(40)22692910 - EMAIL generex@generex.de - WEB www.generex.de (This and all other product datasheets are available for download.)
- Current sensors
The direction of the magnetic field induced by current flow is a probate method to figure out if the batteries are currently in
state charge, trickle charge or discharging. Although the detection rate is slower than querying the UPS. Current sensors
provide additional measurements of the quality of the discharge current. The current sensor selection would be the best
detection source if a UPS state qwery is impossible.
- BACS sensors
The BACS sensors can also perform a discharge detection:
The modules measure the battery voltages - from the moment the voltage drops below the rated voltage, BACS will assume a
discharge is in progress. Since the batteries take a while to fall from the trickle charge to the rated voltage and stay there for a
while before dropping below this value, it is a reliable but very slow option to figure out if a discharge is in progress.
Normally, this detection source is selected if neither UPS nor current sensors are available.
Note
A rechargeable battery needs some time to fall from trickle charge values to it's rated voltage. This natural process can be
misinterpreted as "discharge". For this reason, a battery monitoring or management system needs the ability to differ between this
natural process and a battery discharge:
BACS can do this job and will increase the detection and logging rate only if a real discharge is confirmed.
To improve detection rate, additional current sensors are recommended- if BACS detects a voltage loss as well as current flow, the
discharge status is confimed.
Offset values
BACS modules are calibrated on delivery and will give an exact value related to the calibration. However, the BACS system can not
know the general installation location and it may be possible that the calibrated measurement results differ from external reference
measurements due to the installation site. Air pressure, humidity, ambient temperature and other environmental variables can distort
the values collected by BACS:
The calibrated values need to be corrected if necessary.
With the offset values, it is possible to enter correction values coinciding with measurements at the installation location.
Impedance Measurement Interval
Due to the nature of their function, batteries are subjected by a partial hidden aging process - a gradual process that cannot normally be
observed unless continous measurement data on the internal resistance are available by chance. For reliable trend detection, it is
therefore important to regularly measure the internal resistance of the batteries:
These data logs can be used to identify the real internal age of a battery and thus the probability of a total failure.
Since it is possible to compare all BACS-supported batteries directly with one another using the professional BACS Viewer software, it
is possible to identify an unusual increase in impedance and take appropriate countermeasures.
As a default, BACS will automatically take the first measurement at 8 a.m. after initialization or a restart and then repeat every 12 hours.
However, you can adapt the start time and repetition intervals to suit your service plan.
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