eTower Installation Manual Revision 0
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8.
Switching on the eTower
The Lite is fitted with an “ON/OFF” breaker. When this breaker is switched on the DC
terminals of the eTower may immediately become live if the BMS is active. If the BMS is not
active and the eTower detects an external voltage source the BMS will come alive, observed
by the illumination of LED’s on the front panel.
Note: On some inverters there is a large inrush current when switching on the DC supply. It
is important in these instances to pre-charge the DC bus. With Victron this can be achieved
by switching on the PV to the MPPT’s to allow them to apply voltage to the DC bus before
closing the battery breaker. If this option is not available, you can switch on the AC input
power to the Victron inverter as this allows the inverter to place voltage on the DC bus (it
may be necessary to unplug the Ve.Bus cable from the GX device to allow the inverter to
energise). If you are using inverters that cannot do this, you will need to use a pre charge
resistor.
To switch off the DC output from the eTower switch off the breaker. To switch off the power
to the BMS, press the reset button for 3 seconds and release. If this is not done the BMS will
shut down automatically after 24 hours anyway.
9.
Settings Required for Setting up Inverters and Charge
Controllers
The maximum and continuous discharge currents for the eTower in configurations of one to
four are provided in Table 2.1. The charge current limit should be observed for the current
limit settings of the inverter(s). The average recommended charge current is one third of
the continuous rating of the battery. This will usually ensure that the combination of the
mains charger and the Solar Charge Controller (SCC) does not exceed the maximum
continuous charge current, although this must be specifically checked.
The voltage settings for the eTower when operating in a system where the BMS can control
the external devices as explained above are as follows:
•
Minimum (cut off) – 47V (the Lite should never reach this low voltage but is it good
to have this set as a redundancy protection measure.
•
Low Battery Voltage Warning (if applicable, often used to revert to grid power in
increased self-consumption applications because it approximates 30% SoC) – 51V
•
Max Charge Voltage – 55,8V (Bulk, Absorption and Float are all set to this value)
If the BMS is not able to control the external devices
with remote enable functions, then
the voltages must be set at slightly conservative values. This is to reduce the likelihood that
an outlying cell will reach its voltage limit ahead of the pack, which the external devices
would not be aware of because they can only monitor the total pack voltage. Using a lower
pack voltage to monitor and control charging and a higher voltage for discharge cut off will
allow a greater spread in cell voltage values without any of them reaching their limits.
