I want to add a very simple if possible LED circuit to my solar panel to tell me if it is charging. Basically when the voltage is 14 Volts and above I would like an LED to Light when the panel voltage drops below 14 Volts I would like the LED to Switch off.

I have fitted a 30 Watt solar panel to my gate motor, the motor has 2x 12 Volt 7 Ah batteries in parallel. I just want a visual indicator that the solar panel voltage is above 14 Volts. The maximum voltage of the 30 Watt panel is 17.4 Volts according to the specs on the back of the panel

 

Does it have to be precisely 14V or it can be 13.7V-14.5V.

 

Does it have to be precisely 14V or it can be 13.7V-14.5V.

Hi It does not have to be precisely 14 Volts 13.7V to 14.5V is fine Thank you

 

Hi It does not have to be precisely 14 Volts 13.7V to 14.5V is fine Thank you

Try this:

 

Thank you so much for your help. Its greatly appreciated.

 

Use 1-2W components so they don't overheat.Transistor is BC547/546.

 

Use 1-2W components so they don't overheat.Transistor is BC547/546.

Thank you is 1N4001 diodes correct for D2 and D3

 

Yes,they drop around 0.7V at low currents,the LED should turn on at 13.9V-14V.
I'll breadboard the circuit in few minutes to see if it works properly.

 

Or, if you have an op amp and a Zener, you can do this.

OP amp is powered by the panel, the Zener is 10V and the pot is 1k linear.

 

Thank you is 1N4001 diodes correct for D2 and D3

Diode selection isn't critical. Any silicon diodes you have available or you could substitute a single LED for the two diodes.

 

Can't breadboard it.Only have 3.6 Zener diodes I though I had some 12V but I guess I lost them.Tried modifying the circuit with 3.6V ones but It doesn't work properly.

 

Can't breadboard it.Only have 3.6 Zener diodes I though I had some 12V but I guess I lost them.Tried modifying the circuit with 3.6V ones but It doesn't work properly.

I will build it and let you know how it works out

Thanks for the help

 

OK,it's working on simulator but I don't know if it will in real life.

 

Only have 3.6 Zener diodes I though I had some 12V but I guess I lost them.

2x diodes + 1x 12v zener = ?

X diodes + Y 3.6v zener = ?

 

Have you thought about using a mosfet?

BTW, a tl431 is essentially a comparator and can be made to work here.