Solar Charger (PID 390) Charging Leds

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shaqman
 
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Solar Charger (PID 390) Charging Leds

Post by shaqman »

Hello,

I am using the Solar Charger (PID 390) with a 6v Solar Panel. I notice in full sunlight the chargers red and orange LEDs are lit constantly, however; when the sunlight becomes weaker (say due to clouds), both the red and orange LEDs flicker. The weaker the sunlight the longer the time between each flicker. The stronger the sunlight, the faster the flicker, and when there is full sunlight there is no flicker, the LEDs remain lit constantly. What does this mean? When the LEDs flicker, is the Lithium battery still being charged?

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adafruit_support_bill
 
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Re: Solar Charger (PID 390) Charging Leds

Post by adafruit_support_bill »

When the sun is weak, the panel can't produce enough current at a high enough voltage to effect a charge. Rather than throw away this marginal power, it is used to charge up the large capacitor, and when there is enough of a charge in the capacitor, it is discharged through the charge controller into the battery. So the battery is charging in increments, whenever the led flashes.

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amahpour
 
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Re: Solar Charger (PID 390) Charging Leds

Post by amahpour »

Where can I find test data on this? I'm finding that this "trickle" charge is pretty negligible with respect to my power consumption. Will MPPT be the best solution for cloudy environments?

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adafruit_support_bill
 
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Re: Solar Charger (PID 390) Charging Leds

Post by adafruit_support_bill »

Sounds like you need a bigger panel. MPPT is not such an effective solution for low-voltage applications.
See here:
https://learn.adafruit.com/usb-dc-and-s ... sign-notes
And here:
https://learn.adafruit.com/usb-dc-and-s ... harger/faq

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amahpour
 
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Re: Solar Charger (PID 390) Charging Leds

Post by amahpour »

So the trickle charge going into the BFC (big freakin capacitor) is just as much as the MPPT going straight to the LiPoly? In either case I would have to size up the panel?

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adafruit_support_bill
 
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Re: Solar Charger (PID 390) Charging Leds

Post by adafruit_support_bill »

Pretty much. If you try to pull more current from the panel, the voltage will collapse completely. Both the MPPT and the VPCC+BFC will throttle the current back to avoid overloading the panel. If you want more current in low-light conditions, the only option is a higher capacity panel.

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amahpour
 
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Re: Solar Charger (PID 390) Charging Leds

Post by amahpour »

So higher capacity as a function of current or voltage?

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zener
 
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Re: Solar Charger (PID 390) Charging Leds

Post by zener »

Both. Panels are rated in Watts.

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adafruit_support_bill
 
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Re: Solar Charger (PID 390) Charging Leds

Post by adafruit_support_bill »

As Zener says, panels are rated by watts, where watts = volts * amps.
The solar charger is limited to a maximum of 6 volts, so you need to find a 6v panel with a higher watt rating. We carry 6v panels ranging from 1 watt to 5.6 watts.
https://www.adafruit.com/search?q=solar+panel&b=1

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amahpour
 
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Re: Solar Charger (PID 390) Charging Leds

Post by amahpour »

So in that case if I need to size up to a 6W panel then I need to change the resistor on the solar charging board to handle 1000mA, correct?

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adafruit_support_bill
 
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Re: Solar Charger (PID 390) Charging Leds

Post by adafruit_support_bill »

If your battery can handle a 1A charge rate, than yes. Most of the cells we carry can handle a 1C charge rate. So if your LiPo cell is 1000mAh or larger, then 1A should be a safe rate.

Even without the resistor change, a higher capacity panel will be able to provide more current to the load.

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