Stopping charg from a solar panel

ATmega328p Controller /w pluggable connectors for 6 constant current LED drivers with PWM control
rpu_bus
Posts: 188
Joined: Sun Sep 18, 2016 6:07 pm

Stopping charg from a solar panel

Postby rpu_bus » Sun Dec 03, 2017 3:34 pm

On the RPUlux, I am going to try another approach to charging a battery from a solar panel, but all it will deal with is preventing overcharging.

SolarPwrOptions.png
SolarPwrOptions.png (13.8 KiB) Viewed 27 times


Using IO4 and IO7 to control onboard N-CH MOSFET it is possible to short the solar panel. The blocking diode needs to prevent the battery from supplying current to the short and the panel must be equipped with by-pass diodes. Note that small panels often lack by-pass diodes and shorting a panel without bypass diodes will result in a Zener breakdown failure in the panel.

It is also possible to use IO4 to open circuit the solar panel. This requires more off-board parts but shorting is not an option when by-pass diodes are not installed.

An even better option is to use something like [SunSaver-6L] which will provide a lot of protection. This removes the need to write software that controls the short or open, which if done wrong may damage the battery or hardware on the board.

[SunSaver-6L]: https://www.solar-electric.com/ss-6l.html

rpu_bus
Posts: 188
Joined: Sun Sep 18, 2016 6:07 pm

Re: Stopping charg from a solar panel

Postby rpu_bus » Sat Dec 16, 2017 1:38 pm

For reference, I had some discussion on the Arduino Forum

https://forum.arduino.cc/index.php?topic=514975.15

After letting this soak in a little I decided to add an alternate power input with a PMOS that can be turned on by IO8 from the AVR.

SolarPwrOptions.png
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