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Charging a phone from solar directly?

tomadom

Jan 18, 2013
60
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Jan 18, 2013
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I have a 200w solar panel.
It has an MPPT controller attached to it.
That regulator has a usb port on it.

Normally I use these panels to charge a car battery, but I also want to plug my phone into the usb port on the controller to charge it.

The phone does charge on and off, but not smoothly. It keeps automatically switching into slow charge mode.

I'm sure someone here suggested years ago that this kind of thing occurs due to the irregular current coming from the panels which is why it's better to charge a battery and then the phone.

Someone here also suggested that I could try placing a capacitor between the positive and negative wires to smooth the current. I had small panels then. Is this a good idea, and will it smooth the current?
If so, what sized capacitor should I use?

Thanks
 

dave9

Mar 5, 2017
1,190
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Mar 5, 2017
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1,190
It depends on the amount of time the output drooped below whatever threshold the phone considers too low for fast charging. You'd have to measure and calculate from that, but if the duration is long enough to notice then it will need a lot of capacitance.

It would probably be easier, and cheaper to just use batteries to overshoot needed capacity rather than an array of supercapacitors, especially if you use more cells than the peak voltage would top off so you don't need a regulated charge circuit.

For example 4 x AAA in series, if the USB output never gets above ~5.5V then they can never overcharge. Even 4 x AAA might not be enough, you really have to measure for worse case scenario you want to cover.
 

tomadom

Jan 18, 2013
60
Joined
Jan 18, 2013
Messages
60
It depends on the amount of time the output drooped below whatever threshold the phone considers too low for fast charging. You'd have to measure and calculate from that, but if the duration is long enough to notice then it will need a lot of capacitance.

It would probably be easier, and cheaper to just use batteries to overshoot needed capacity rather than an array of supercapacitors, especially if you use more cells than the peak voltage would top off so you don't need a regulated charge circuit.

For example 4 x AAA in series, if the USB output never gets above ~5.5V then they can never overcharge. Even 4 x AAA might not be enough, you really have to measure for worse case scenario you want to cover.
It drops out for 1 or 2 seconds at a time. It seems to be a product of the solar output.
 

tomadom

Jan 18, 2013
60
Joined
Jan 18, 2013
Messages
60
It depends on the amount of time the output drooped below whatever threshold the phone considers too low for fast charging. You'd have to measure and calculate from that, but if the duration is long enough to notice then it will need a lot of capacitance.

It would probably be easier, and cheaper to just use batteries to overshoot needed capacity rather than an array of supercapacitors, especially if you use more cells than the peak voltage would top off so you don't need a regulated charge circuit.

For example 4 x AAA in series, if the USB output never gets above ~5.5V then they can never overcharge. Even 4 x AAA might not be enough, you really have to measure for worse case scenario you want to cover.
Thanks for the reply mate. I'll just have to put a power bank in between the panel and the phone. As you said, the batteries are a good idea in this case
 
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