Studer BSP 1200, Руководство пользователя

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Studer Innotec SA
BSP
User Manual V1.0.3 7
1. Introduction
The BSP (Battery Status Processor) is designed to monitor lead-acid batteries used with inverter-chargers of
the Xtender range. An advanced algorithm provides the battery state of charge in real time in order to best
optimize its use.
The BSP offers voltage measurement for 12, 24 and 48 V nominal batteries as well as current measurement
with a resistive shunt. Thanks to the Xtender communication bus, the BSP is able to communicate with the
other devices of the system. The remote control RCC-02/-03 makes it possible to configure the BSP and to
display the values that it measures. More than this, the Xtender inverters can react according to various data
given by the BSP.
1.1. General ideas over batteries
The lead-acid batteries are energy storage with a complex behaviour. They consist of 2 Volt (V) nominal cells
in series to reach the required voltage. Due to different physical and chemical phenomenons they can show,
depending on the conditions, a behaviour quite far from the reservoir that simply fills up and empties out. This
is the reason why the battery state of charge is complex to determine and why a lead-acid battery monitor
is not as precise as, say, a petrol gauge.
The different values that affect a battery are described here below.
1.1.1. Defining the capacity
The battery capacity is defined as the quantity of electrical charge that a full battery can supply at given current
before reaching a certain voltage. The unit generally used is the Ampere-hour (Ah). An ideal battery of 100 Ah
will for instance supply 10 Amperes (A) during 10 hours or 1 A during 100 hours.
The capacity is usually given for a new battery, at 20 °C, with a discharge down to 1.8 V per cell (10.8 V for
12 V nominal, 21.6 for 24 V and 43.2 V for 48 V). The time of discharge is given by the letter C followed by
the duration in hours, like C10 for 10 hours.
To make them reach the given capacity, the manufacturers charge their batteries according to standard
procedures (for instance as per the norm IEC-60896-11). This kind of charge can last up to many tens of
hours at very high voltages, which is rather far from normal conditions of use. This is why the real available
capacity is lower than what is given by the manufacturer.
1.1.2. Capacity and temperature
The capacity varies according to the temperature of the active substance of the battery. A decrease of the
temperature will lead to a decrease of the capacity and an increase of the temperature to an improvement
of the capacity.
1.1.3. Capacity and cells imbalance
Despite the fact that always the same current goes through the 2 V cells of a battery, factory differences, even
small, might make their state of charge uneven. In case of imbalance, the most discharged cell determines
the end of discharge.
Therefore the cells in series must always be of the same model and have the same history of use. One of the
objectives of the absorption and equalization steps is to even out the charge of the cells in series.
1.1.4. Capacity and discharge current
The capacity goes down when it comes to big discharge currents. The active substance in the battery needs
time to spread into the cells and a quick discharge will lead to a capacity decrease.
To convert the capacity from a discharge duration to another, one can use Peukert formula.