800.261.3602
Revised 07/18
Description of Operation
The SunExplorer III is a six (6) stage, micro-processor based, Pulse Width Modulated (PWM), and
Multi-Point Tracking (MPT), solar charge controller. The controller connects between the solar
panels and 12VDC storage batteries to regulate charge. The SunExplorer III controller maintains
maximum charging rates throughout each of the charging stages, maintains battery life by
protecting it from over charging or under charging by regulating the PWM rates, and disconnects
the batteries at night to prevent discharge thru the solar panels. The SunExplorer III provides an
automatic equalization stage for lead-acid (wet) batteries that are drained down to 12VDC.
The SunExplorer III monitors both the battery and solar panel voltages and determines when and
how to charge the battery. Each morning, when solar panels produce a voltage greater than
10VDC the display portion of the controller wakes up and checks for a low battery/ equalization
flag and the current battery voltage to determine which charging stage to enter, soft charge
(Batteries less than 10VDC) or bulk charge. When the solar panel voltage reaches 16.0VDC the
controller enters the bulk charging stage, charging the battery up to the bulk charge voltage. The
SunExplorer III then enters the absorption stage and begins modulating its charging PWM
algorithm to maintain the bulk charge voltage. The absorption period is based on the battery
voltage before it started charging. Once it completes the absorption phase it then drops into the
float stage, maintaining the battery voltage at 13.7V by adjusting its PWM algorithm to
compensate for varying solar (sunny/cloudy) and DC load conditions to maintain float voltage. If
solar or load conditions are such that the battery voltage is pulled below 13.0VDC for more than
10 minutes an auto boost flag is set and when the conditions improve and the battery voltage
returns to the float voltage the controller sees the boost flag and performs the auto boost routine
then returns to the float stage. When the solar panels output drops below 10.0 volts the
SunExplorer III enters its night or end of day mode.
The SunExplorer III performs the following functions:
1.
Monitors both battery and PV voltages to determine when to begin its charge routine each
day and how it is to progress through its charging stages.
2.
Monitors the battery temperature sensor and compensates for rising or falling battery
temperatures (requires battery temperature sensor AEI-LM335t).
3.
Monitors for low battery voltage, when detected it will blink the battery voltage LED and
display the battery voltage.
4.
Compensates for varying solar (sunny/cloudy) and DC loads conditions by adjusting it,
PWM charging algorithms to maintain an optimum float charge.
5.
Auto boost feature will occur when the controller cannot maintain float voltage due to
excessive loads and the battery voltage is pulled down below 13VDC. Charge Status LED
Indicates which stage the controller is in: Red - Bulk and Absorption, Green - Float, Orange
- Equalization, Blinking Green - nearing end of day, Charge Status LED OFF – Night
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