This contains a photovoltaic charge controller and a low voltage load disconnect circuit. It can be used to handle all of the power functions for small 12 Volt solar powered devices.
The low voltage disconnect has a load on-off switch, and a battery low voltage indicator. By using the SPC2 as the center of a solar powered device, long battery life is assured. The SPC2 is primarily designed to be a solar lighting controller, it can be used to power radios and other high capacitance loads with a minor switch and circuit modification.
The circuit was designed with the following goals:
Single board smart light switch.
Analog simplicity with common parts for ease of repair.
High efficiency: low loss charging and minimal idle current.
Radio-quiet operation, low frequency charge control switching.
Nominal battery voltage: 12V
Maximum solar panel current: 6 Amps
Maximum load current: 6 Amps, more with an external solid-state relay
Night time battery drain current: approximately 10 micro-amps
Temperature compensation for use in variable climates
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