Blue Sky SC30 - Manual (Page 5)

Installation and Operation Manual
4
The amp-hour counter displays total solar charge amp-hours accumulated since the last time the counter was cleared up to a maximum count of 999
amp-hours. Amp-hour production varies widely with operating conditions, but as a very broad brush approximation 100 watts of PV modules can deliver up to
a maximum of about 30 amp-hours per day. Any partial shading, lower sun intensity, shorter days, or time spent in Absorption or Float will decrease amp-
hours produced. The present amp-hour count may be cleared by pressing Display Select for 5 seconds while viewing amp-hours on the display.
BATTERY LEVEL GRAPHIC
The SC30 provides a battery level graphic on the front panel which indicates approximate battery level versus battery voltage. Generally a higher voltage is
better than a lower voltage. Note that the graphic does not illuminate.
A battery that is being charged will typically range in voltage from about 12.5 volts after charge commences, to perhaps 14.0 volts or greater when the
battery is highly charged. Once charge stops and the battery begins discharging and delivering power to a load it is normal for battery voltage to drop. A battery
under a light load of about 1 amp per 100 amp-hours of battery capacity may range between about 12.5 volts when the battery is full, down to perhaps 12.0 volts
when the battery is about 50% discharged. Battery voltage during discharge will tend to be higher under light load and lower under a heavier load.
Do not think of these voltage values as absolutes but rather as a broad brush indication of battery level. Voltage at a particular state of charge will vary with
battery size, age, construction, temperature, and with the level of charge or discharge current. Most battery manufacturers recommend not discharging below
about 50% DOD (depth of discharge) to promote improved battery performance and life. Avoid allowing battery voltage to drop below about 11.5 volts, and NEVER
allow battery voltage to drop below 10.0 volts.
FRONT PANEL OPERATION & INDICATORS
FIGURE 1
3-STAGE CHARGE CONTROL
The SC30 is factory configured for a 3-stage charging process, Bulk, Absorption and Float, which is fully automatic and requires no operator
intervention. The 3-stage charge process applies a somewhat higher Absorption charge voltage to charge the battery quickly and safely. Once the battery is
fully charged a somewhat lower Float voltage is applied to maintain the battery in a fully charged state without excessive water loss.
¾ The charge control system always starts in Absorption and will return to Absorption upon exiting Current Limit or Equalization.
Following a 20 second delay in Absorption the SC30 may move on to other charge modes based on battery and system needs.
Bulk Charge
The SC30 will switch to Bulk charge when battery voltage remains below the present charge voltage setpoint. During Bulk the SC30 delivers as much
charge current as possible to rapidly recharge the battery. During Bulk it is a combination of battery size, state of charge and available charge current that
determine battery voltage, not the SC30.
Absorption Charge
When the battery recovers sufficient charge for battery voltage to rise to the Absorption Charge Voltage setpoint (factory set to 14.4V), charge current is
reduced as necessary to hold the battery at the Absorption Voltage. The SC30 remains in Absorption until the battery is fully charged as determined by the
SC30 remaining continuously in Absorption for the Absorption Charge Time period (factory set to 2 hours). The SC30 will return to Bulk should battery
voltage remain below the Absorption Voltage setpoint for more than 20 seconds.
Float Charge
Once the battery is fully charged a somewhat lower Float Voltage (factory set to 13.2V) is applied to maintain the battery in a fully charged state
without excessive water loss. The SC30 will return to Absorption should battery voltage remain below the Float Voltage setpoint for more than 20 seconds.
Charge Status LED’s
Shows present charge mode.
Setup Push-Button
Used with Display Select to
view or change charge
parameter settings.
Digital Display
May show battery voltage,
solar charge current, or solar
charge amp-hours. AMP
indicator be on if showing
solar charge current. Display
automatically dims at night.
Display Select push-button
Selects display mode. May
also be used to clear solar
charge amp-hours or
start/stop Equalize.
Front Panel heating
Panel serves as a heatsink
for power control devices,
may become quite warm
during normal operation.
Battery Level Graphic
Shows approximate battery
level vs. battery voltage.
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