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Topic: How to modify the voltage of solar charger? (Read 5944 times) previous topic - next topic


To automatically charge during daytime and to automatically light during night time.

Basically, the kind of behavior of an industial photovoltaic lighting system.

My plan is to use the photodiode current to close the charging branch of the circuit (now done manually by SW1).


Everything is here, battery is charged all the time = no switch to turn off charging.
The LED is turned on by photoresistor.


Thank you @ted!

The photoresitor I can find here is  5528, which is recommended to be part of a voltage divider by a 10 K resistor (5V, Arduino).

The 5528 Value in light is 8K to 20K (according to its specifications).

My circuit is 3.6 V (3 NiMH x 1.2V) so I guess the R2 resistor shall be around 68-75 K - if going by the posted schematics.

I also think that the R1  value of 330  shall be reduced to fit the lower voltage - maybe to 100.


R2 - put potentiometer 100k, R1 don't go to low, the LED are cheap, so you can play with resistor.,


Ok, Thank you!

Now the fun part is to adapt, design and mount this new module without changing anything in the existing circuitry, so I can revert to the manual command anytime I like to.


Jun 17, 2018, 10:42 am Last Edit: Jun 17, 2018, 10:44 am by falexandru
As promised, the solar charger demo final prototype:

The solar charger uses the simple 2-diodes design, so it is easy to explain what is in and how it works. Not recommended however for actual devices, which may require more efficiency and reliability.

It is still assembled by screws and make use of barrel connectors - for portability reasons among various sizes and types of PV panels.

Screws are not a good choice for they are easy to un-screw  by themselves by manipulation of the device alone.

However, the modular design makes possible to interact with my sensors and with the vertical axis wind turbine.


Note: I did not cut the components terminals on purpose, because they act as a sort of "guard" to the circuit. :-).

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