Author Topic: Solar Charger Woes  (Read 971 times)

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Offline MukrakiishTopic starter

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Solar Charger Woes
« on: June 23, 2017, 01:25:02 pm »
Newbie question here...I can't seem to figure out what the problem is.

I built #2 in the diagram there since I didn't have a BC557 I replaced it with a 2N3906. For some reason, there is always a voltage getting back through the diode/transistor into the solar panel which subsequently discharges the battery pack. It charges just fine in the daylight but nothing stops the solar charger from draining the battery pack. This seems pretty simple but am I overlooking something obvious? I'm fairly sure since it's a PNP that I'm following the pinout correctly (EBC) with emitter being the top of the transistor in the schematic.  :-\

Currently, I have the lights disconnected, just wanted to verify if the design would work, which it doesn't. Bah.
 

Offline MukrakiishTopic starter

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Re: Solar Charger Woes
« Reply #1 on: June 23, 2017, 01:41:18 pm »
Wait...hang on.

If there is no light connected, there will be insufficient voltage difference to change the transistor over from one state to the other, which would connected the solar panel to the battery with a voltage drop across the 470 resistor correct? Which would cause the battery to drain backwards through the panel instead of draining it into the LED's.

The transistor wasn't supposed to ever put a "full hold" on the battery so much as just redirect the power continuously from one source to the other.

Am I on the right track?
 


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