ST – II Series POWER SUPPLIES USER INSTRUCTIONS
AC/DC Power Supply: This provides an isolated 13.65Vdc output for powerin of the load and
float char in of the battery. Battery current is sensed and monitored by the power supply to ensure
that the maximum char in current is not exceeded.
Battery Features: The power supply provides full battery mana ement as per the followin .
The power supply is a four sta e battery char er with Boost (VBoost = 14.05V), Float (VFloat =
13.65V), Store (VStore = 13.25V) and Trickle char e modes to ensure lon battery life.
Charging current is limited to a maximum of 10A (ST20-II) and 15A (ST35-II). This provides
optimum life for the batteries.
To char e at the maximum battery char e current above, ensure the load current plus battery current
is equal or less than the maximum output current. The char in current will be reduced in situations
where the difference between the rated output current and the load current (the available char in
current), is less than the maximum char in current.
Also note that the battery current sense is provided in the “Batt +ve” battery output. For this feature
to work, the load “+ve” and battery “Batt +ve” should not be cross connected. (Appliances should
not be connected to both the “Batt +ve” and “+ve” terminals of the power supply. Appliances
should be connected to the “+ve” and “-ve” load terminals).
Low Voltage Disconnection of the batteries is provided to prevent deep dischar e of the battery.
Automatic reconnection occurs when battery volta e recovers.
Battery Current Drain is less than 2mA.
Trickle Charge to the battery is always present. When the battery volta e is below the LVD (Low
volta e disconnect) re-connect volta e (<10V and the mains power or auxiliary power is available,
the battery will be char in at 0.8A. When the battery volta e is sufficient (>10.5V for first power
up, 11.5V and 11.7V for subsequent reconnection with and without mains respectively) the LVD
will connect the battery and allow float char in at 10A/15A (ST20-II/ST35-II). The Trickle
Char e feature is provided to allow “very” flat batteries to be char ed at a rate, which will extend
their life.
Auxiliary Power Input: The power supply terminal “Aux In +VE” provides an alternative option
for powerin of the load and float char in of the batteries when mains volta es are not present.
This input is to be powered by a suitable +12V system. (i.e. CAR). The volta e of the auxiliary
power source should not exceed 14.8 volts.
When operatin via the external input, current and volta e control for the battery must be provided
from the external source. The ST20-II/35-II does not provide battery current limit or volta e control
when operatin in this confi uration. Trickle Char e is still functional when powered throu h
“Aux In +VE” terminal of power supply.
Suitable fuse protection must be provided for this input. A fuse ratin not exceedin 20 Amps for
ST20-II and 30 Amps for ST35-II must be used.
Solar power should be connected directly across the battery terminals with a volta e re ulator in
series. A solar panel volta e re ulator with maximum output volta e not exceedin 14.8 volts must
be used at all times. Failure to use a volta e re ulator may result in power supply dama e.
Generator 12 volt outputs should not be connected across battery terminal whilst battery is
connected to power supply or connected to the “Aux In +VE” terminal of power supply. Serious
power supply dama e or internal explosion may occur. If a flat 12 volt battery has to be char ed
usin the enerators 12 volt output, it should first be disconnected from the power supply. Once
battery has bein char ed it can then be reconnected to power supply.
Pa e 2 of 11 Issue F
