The smart bypass diode has some other advantages too.
It also will give others some future proofing if they go with higher voltage solar panels and add more peripherals to their setup. I'm planning on adding more later.
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DC Reverse voltage 30V Maximum
Forward current 8 A Typical 15 A Maximum
Forward voltage = 26 mV ( At 8 A, T = 25°C )
Reverse leakage current = 0.3 µA (28 V Reverse Voltage, TJ = 25°C)
3.3 µA (28 V Reverse Voltage, TJ = 125°C)
I figured regardless of what voltage I choose, the 0.7v voltage drop of the zener diode (i.e. post no. 1, Nick gammon's example of using 1N752 zener diode, Barebones Atmel 328p Solar powered Arduino is not allowing for full collection of my solar panel's power output. So on overcast days I instead of 5V I could be getting 4.3 volts, etc....
So I was trying to drop losses in efficiency with the smart bypass diode.
Also the leakage current from the super capacitor to the solar panels was a concern.
With the smart bypass diode it's 3.3 uA at 28V.
With the zener diode it becomes higher at lower voltages correct?
Then there is the issue of how much current/power the zener diode can handle.
1N752 specs
It seems for the 5.6V zener diode it's 60 mA.
1N746A its 3.3V and 110 mA
Based on the super capacitor datasheets the max currents they can handle are 8 amps, so even if I used the 6V, 1.6 amps (won't get this max value likely). I won't really be stressing out the supercapacitor correct?, so that's why I didn't add a resistor (plus they have their own wattage ratings too of what they can handle).
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Plan is to build a weather monitor and send values to the Arduino IoT cloud, it can remain fully active at day time and send periodic updates during night time and do deep sleeping in between those periods during night time.
Right now with my DC power supply, I'm getting.
3.3V and 0.118 A (without WiFi being on and sending data to cloud)
With these peripherals (getting these currents from the data sheets, i.e. continuous power mode,etc):
ADPS (.79 mA ??, 12.5-100 mA led drive current - gesture detection)
(i'm using it to detect color/ ambient light to initiate deep sleep mode, etc...)
Neo 6m gps (47 mA)
BME680 (18 mA)
Want to add an encoder to for wind speed detection (one I selected =<80 mA max current consumption, 40mA load current)
Datasheets for peripherals:
NEO6M GPS
BME680
Encoder for wind speed
ADPS-
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