Specifications

8
fool the PowerCenter if the battery bank is small
and the wind gusts are strong. High charging cur-
rent can raise the battery bank voltage too high for
a short period (several seconds) and put the Po-
werCenter into Blown Fuse Mode. We recom-
mend a battery bank of at least 220 Ah to avoid
this possibility. Also if you have a PV array or in-
verter-charger that could momentarily create a
battery voltage above 35 VDC they will initiate the
Blown Fuse Mode.
Operation of Controls and Factory Set-
tings
The PowerCenter will automatically switch the
XL.1 wind turbine, the optional photovoltaics (PV)
array, and the optional dump load on and off to
maximize energy capture and prevent battery
overcharge. The PowerCenter’s microprocessor-
based smart controls determines these switching
functions based on the battery bank voltage.
At battery voltages below the regulation voltage
(factory set at 28.1 VDC), the wind and solar are
connected and allowed to charge the batteries. At
wind speeds below approximately 8 m/s (18 mph)
the turbine LED (green) will blink slowly to indicate
that the controller is boosting the voltage from the
turbine up to battery voltage. This “low end boost”
function ensures that the maximum possible pow-
er is extracted from the turbine at low wind
speeds, and allows the turbine to produce power
down to as low as 2.5 m/s (6 mph) under ideal
conditions. In higher winds the turbine produces
enough voltage to charge the batteries directly
and the boost function is turned off. Once the
wind turbines passes out of boost, its green Sys-
tem Status LED will quite blinking and become
continuously lit.
If the battery voltage rises above regulation vol-
tage the Extra Load (dump load) circuit is ramped
up to control the battery voltage. The maximum
allowable resistance load that can be placed on
the dump load circuit is 0.5 ohms, producing a
maximum current of 60 amps. When the XL.1
and the solar are producing more output than the
batteries and dump load will accept, then the PV
will be turned off. If the battery voltage continues
to rise then the turbine will be put into Slow-Mode
operation.
In Slow-Mode the maximum turbine power is 120
watts, if the dump load and batteries can use
more power, then the PV will be cycled on and off
to provide as much power to the dump load and
batteries as possible.
While in Slow-Mode, if there is no dump load, the
turbine will be slowed as the batteries come up to
a full state of charge. If some additional electrical
load is turned on, the turbine will increase its
speed up to approximately 130 RPM, to provide
more power in order to keep the batteries topped
up.
Slow-Mode is exited after the battery voltage re-
mains below regulation voltage minus 1.5 VDC
(factory setting of 26.6 V DC) for 13 minutes.
Slow-Mode is also exited if there is a large load
placed upon the system that pulls the voltage
down to regulation voltage minus 2.5 VDC (25.6
VDC factory setting) for 25 seconds.
The PV will be turned on anytime the controller
senses that the dump load is not at maximum
power, and there is sufficient sunlight. While in
Slow-Mode there is no preference for either the
XL.1 or the PV, if the controller decides that it
needs more power when it is deciding to turn the
PV on or off, then the PV will be turned on. Like-
wise for the turbine, as the PowerCenter decides
whether or not to increase the RPM and power
from the turbine it looks at the battery voltage at
that instant. This control of the two sources opti-
mizes the two resources to keep the batteries at a
peak state of charge.
The Extra Load (dump load) is Pulse Width Mod-
ulated (PWM). Effectively this gives “infinitely”
variable adjustment of the voltage applied to the
attached load. The load resistance controls the
maximum current that is drawn, and no load
should be connected that will draw more than 60
amps. In this system amperage, voltage, and
load resistance are related by the formula:
AMPS = 30 V / RESISTANCE
Any dump load resistance higher than 0.5 OHMS
will work with the PowerCenter controller. Smaller
dump load resistances will overload the circuitry
and may damage the PowerCenter. Note: not all
multi-meters will accurately measure the resis-
tance at such low values. Suitable dump loads
must also be designed and installed such that
they will not overheat and/or cause a fire hazard.
To determine the required heat dissipation rating
of the heater (resistor), calculate the AMPS as