MorningStar SunSaver 20 Amp 12 Volt PWM Charge Controller
Options: LVD Override Protection
Manufacturer Part Number: SL-20L-12V
Morningstar’s advanced SunLight (SL-20L-12V) solar charge controller combines the SunSaver design with a microcontroller for automatic lighting control functions.
This technology provides:
- Proven Reliability
- Precise Lighting Control
- PWM Battery Charging
The MorningStar SunLight controllers combine the features of the SunSaver controllers (including LVD) with an adjustable automatic lighting control circuit. This allows you to connect a DC light and have it come on at dusk for a set period of time or dusk-to-dawn. It's 10 position rotary switch lets you choose exactly how your DC light will operate.
Three Versions Available:
- 12 Volt: 10 and 20 amp ratings
- 24 Volt: 10 amp rating
- Microcontroller digital accuracy
- Fully automatic operation
- Ten field adjustable lighting control options
- Special on/off/on functions
- Manual test capability
- LVD override protection
- Detects day and night using the PV array
- Suitable for all 12/24 Vdc lamps
- Sealed/Flooded battery select
- Temperature compensation
- Parallel with a SunSaver for 40 amps solar
- Includes SunSaver battery charging circuit
- Rotary digital switch to select among
10 lighting options (see back)
- Test button flashes red LED to confirm
correct rotary switch selection
- Test button turns lights on for 5 minutes
(in LVD limited to 3 times)
- LVD overrides lighting timer
- Sunrise overrides lighting timer
- Timer accuracy is within 2 seconds
|Rated Solar Input
|25% Current Overload
| 11.7 V
| 23.4 V
| 12.8 V
| –40 to +85°C
Green: The green LED indicator will light whenever sunlight is available
for battery charging. The green LED will turn off at night.
Because the SunLight uses a PWM constant voltage charging
process, there is usually some amount of energy going into the
battery at all times. Although the charging current falls to very
low levels when the battery reaches full charge, the green LED
will continue to stay ON all day. This is to indicate that the
controller is working and that energy is available from the PV
array for charging.
Red: The red LED is an indicator for 3 different functions:
- Automatic low voltage load disconnect (LVD)
If the battery charge state falls below the LVD setpoint, the light
will be disconnected and the red LED will light. This indicates the
controller has disconnected the load to protect the battery from
further discharge and possible damage. The red LED will turn off
when the battery recovers to about 50% of its rated capacity and
the load is automatically reconnected.
- Initial controller start-up
When the SunLight is properly connected to the battery, the red
LED will flash 3 times.
- Confirm lighting control selection
When the TEST button is pressed, the red LED will confirm the
lighting control option selected by the rotary switch
To select a lighting option, turn the rotary digital switch to the
desired position. An arrow in the rotary switch will point to the
selected position. This is a digital switch, so it will click into
each of the ten positions:
| Lights remain turned off
| Hours light is turned on after sundown
|3/1, 4/2, 6/2
| Light is turned on after sundown, turned off during the night, and turned on again one hour (3/1) or two hours (4/2, 6/2) before sunrise
| Dusk-to-Dawn, light is on all night
- Wire size: #10 AWG (5.2 mm2)
- Anodized aluminum case
- Marine rated terminals
- Epoxy encapsulated
- Weight: 9 oz (0.26 kg)
- Polarity Protection
The SunLight is generally protected from reversed connections,
but the system operator and other equipment will be at risk
when polarities (+ and –) are reversed. Carefully check before
making each connection to be certain the polarity is correct.
- Brownout Protection
If battery voltage sags below 8 volts for any reason (such as
pressing TEST in LVD with a weak battery), the microcontroller
may reset. This is to prevent a low voltage condition from
causing the microcontroller to lock-up at an unattended site.
Note that a brownout reset will begin a new start-up sequence
for measuring night length.
100% Solid State
All power switching is done with FETs. No mechanical relays are
used in the controller.
- Battery Charge Regulation
SunLight uses an advanced series PWM charge control for constant
voltage battery charging. A true 0 to 100% PWM duty cycle
is very fast and stable for positive charge control under all system
- Day-Night Transition
The SunLight uses the solar array to detect day and night. The
transition to night requires a solar insolation level less than 2
percent. The transition back to day requires a high solar array
open-circuit voltage. Both state changes require 10 minutes of
continuous transition values before making the change. These
constraints avoid false transitions due to lightning or dark storm
- Measure Night Length
The LIGHTING CONTROL options that turn the lights on again
before sunrise require that the SunLight measure the length of
the night. Therefore, the controller cannot turn the lights on
before sunrise the first night after installation (or after reconnecting
the battery). If the solar array is disconnected during service,
the controller will then measure a faulty night length. Either reset
the controller by reconnecting the battery, or this short “night”
will be automatically corrected by the controller after 4 days of
- Temperature Compensation
A sensor next to the green LED measures ambient temperature
conditions. The SunLight corrects the constant voltage setpoint
–27 (or –54) mV per °C with a 25°C reference. This correction
matches the battery charging to the changing electrochemical
properties of the battery, and works best if the battery and controller
are in a similar thermal environment.
- Sealed / Flooded Select
Flooded batteries require more vigorous charging to avoid stratification,
and sealed batteries require precise control to avoid outgassing.
The SunLight constant voltage setpoints are 14.4 volts
for flooded batteries, and 14.1 volts for 12 volt sealed batteries.
- LED Indicators
- Low Voltage Disconnect (LVD)
If the battery falls below 11.7 (or 23.4) volts, the load is disconnected
from the battery to protect against harmful deep discharges.
A one minute delay prevents load disconnects from
transients. The load is automatically reconnected when the battery
voltage recovers to 12.8 (or 25.6) volts.
- Battery Disconnect
If the battery is disconnected during the daytime, the PV array
will continue to provide power to the controller. The SunLight will
immediately go into PWM and provide power at a constant voltage
to the load. This will continue as long as sufficient power is
available from the PV array.
- Parallel Controllers
Morningstar controllers work very well in parallel configurations.
No blocking diodes are required. The only constraint is that each
controller must have an independent and separate PV subarray
and load. Make sure that each controller’s rating for PV and load
current is not exceeded.
- Auxiliary Generators
Engine generators and other sources of power may be connected
directly to the battery for charging. It is not necessary to disconnect
the SunLight from the battery. However, do not use the
SunLight to regulate these other generators.
- Reverse Current
The SunLight prevents the battery from discharging through the
PV array at night. There is no need to install a blocking diode for
Warranty: Five year warranty period. Contact Morningstar for complete terms.