Product Manual

10
• Battery Charge Regulation
SunLight uses an advanced series PWM charge control for con-
stant voltage battery charging. A true 0 to 100% PWM duty cycle
is very fast and stable for positive charge control under all system
conditions.
• 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
clouds.
• 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 reconnect-
ing 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
service.
N OTE : The SunLight uses the open circuit voltage of the
PV panel to determine the correct time for dawn
and dusk. If the PV panel is covered with debris
(e.g. snow, leaves, dirt), the PV panel voltage may
be too low which can cause load timing errors.
If the load is operating erratically, make sure the PV
panels are clean, there are no obstructions shading
the array, and the PV panels are oriented to the sun
correctly. The SunLight will automatically correct load
timing errors within 4 days of clearing the array.
• 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 con-
troller are in a similar thermal environment.