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Morningstar SG-4 > SunGuard 4.5 Amp 12 Volt PWM Charge Controller

Morningstar SunGuard 4.5 Amp 12 Volt PWM Charge Controller -  SG-4

Our Price: $26.30
Warranty: 5 Years


Description Data Sheet

MorningStar SunGuard 4.5 Amp 12 Volt PWM Charge Controller

Manufacturer Part Number: SG-4

Morningstar's SunGuard SG-4 is the world's leading single module controller. We have combined all the advantages of our SunSaver charging circuit with less expensive packaging to provide an economical controller for small PV systems. Morningstar’s SunGuard is the most advanced small, economical solar charge controller on the market today.

SunGuard’s technology provides:

  • Exceptional Reliability
  • PWM Battery Charging
  • Consistent High Quality
  • Low Cost


  • ISO 9002 quality programs
  • Series design (not shunt)
  • 100% solid state
  • True 0 to 100% PWM duty cycle
  • Setpoint accuracy to 60 mV
  • Temperature compensation: A sensor measures ambient temperature and corrects the constant voltage setpoint by –28 mV per °C with a 25°C reference. This works best if the SunGuard and battery are in a similar thermal environment.
  • Rated for 25% overloads
  • No need to derate
  • Lightning protected with 1500 W transorbs
  • Self-consumption is 6 mA
  • Fully encapsulated in epoxy potting
  • ABS plastic, impact-resistant case
  • Outdoor rated, Hypalon connecting wires


SunGuard can be mounted outdoors. Do not expose to ambient temperatures above 60°C. Make sure that water will drain from inside the case.

SunGuard’s PWM charging compared to On-Off solar regulators:

  • Typically 30% more solar energy into the battery per day
  • Average battery State-of-Charge is 90 – 95% compared to 55 – 60% for On-Off regulators


Rated Solar Input 4.5 Amps
Max. Input (5 min.) 5.5 Amps
System Voltage 12 Volts
Max. Solar Voltage 30 Volts
Regulation Voltage 14.1 Volts
Accuracy 60 mV
Self-consumption 6 mA
Temp. Compensation –28 mV/°C
Reverse Current Leakage<10 uA
Operating Temperature –40 to +85°C

Detailed Description

The MorningStar SunGuard is a fully epoxy encapsulated outdoor rated 4.5A "ice cube" sized 12V PWM charge controller. It has built-in temperature compensation, lightning protection and easy 4-wire hookup. The SunGuard's regulation voltage is set at 14.1 (best for sealed or gel batteries) and is not adjustable for battery type like MorningStar's other controllers. It's dimensions are 2.5" x 2.0" x 1.5" and it weighs just 3 oz. Use only with a 12 volt battery.

The SunGuard is able to match the quality and performance of the world-leading SunSaver controllers because:

  • SunGuards are made on the same high speed, automated production lines
  • SunGuards use the same charging circuit
  • SunGuards use the same high quality components

Advanced PWM Battery Charging

SunGuard uses an advanced series PWM charge control for constant voltage charging. A true 0 to 100% PWM duty cycle is very fast and stable for highly efficient charging.The SunGuard prevents the battery from discharging through the solar array at night. There is no need to install a blocking diode for this purpose.

SunGuard Battery Charging

Warranty: Five year warranty period. Contact Morningstar for complete terms.

Average Customer Review: 4 of 5 Total Reviews: 1 Write a review.

Morningstar RD-1 > Relay Driver for Tristar Controller
Our Price: $122.15

Morningstar RD-1 - Relay Driver for Tristar Controller

  1 of 1 people found the following review helpful
Solar Power for your boat lift August 4, 2011
Reviewer: CC from W. Bloomfield, MI United States  
I would give this 5 stars, but the 1st solar controller I bought cracked internally and stopped working.  With the new one, I see a note that indicates that it will fail if exposed to temps over 140F - news to me, but I may have missed the info several years ago when I bought the 1st one.  The controller could certainly have been made to work at higher temperatures, like temps seen in a black battery box sitting in the sun on a dock (use battery to power my boat lift, battery box is now painted white to solve heat problem).

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