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Smoothing a charging current for a phone?

tomadom

Jan 18, 2013
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Have I mentioned an MPPT charger yet? And you need to charge the battery directly. Charging a power bank via the USB charging port has the same inherent problems as directly charging the phone.

Something like this or this.
Thanks for the reply. Given that the solar panels are more likely to under produce than over produce power I'm not sure how a MPPT controller will help here. I've quoted someone from another forum on why this may be the case. MPPT controllers control how they use the input current where is a buck boost converter will not. My concern is with the output current remaining the same.
I think my main concern is having the optimum output voltage regardless of the input voltage.. I could be missing a point about MPPT controllers here. Maybe you can correct my understanding here.

Quote below.
" The MPPT controller uses an algorithm to determine and use the optimum power of the panel. It dynamically adjusts the switching regulator's use of current to keep the power transfer at a maximum as all these things change. A BB regulator simply provides a constant output voltage without regard for controlling its use of input power."
 

BobK

Jan 5, 2010
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The MPPT controller must be used to charge a battery directly. It puts as much energy into the battery as it can under varying conditions. Once the battery has enough energy to charge the phone, you would hook it up to a buck or boost converter to get 5V to charge the phone.

Bob
 

tomadom

Jan 18, 2013
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I see what you'er saying. The MPPT controller sits between the solar panel and the battery. The buck boost converter sits between the battery and the phone.

Is that right?
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Yes. But you have to make sure your MPPT controller is suitable. Most are a buck configuration -- they assume that the solar panel voltage will always exceed the battery voltage.
 

tomadom

Jan 18, 2013
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I have one more question / query in relation to this topic if any of you are still reading this. I recently tested the output voltage of my USB phone charger with a USB Voltmeter / Amp Meter and noticed that even when I unplugged the charger from the mains, the voltmeter / Amp Meter stayed lit up and showing the same voltage for about 10 seconds after I unplugged it. I think this is the kind of effect I want when charging from a solar panel or other. Will a buck-boost converter or a MPPT converter do that? OR.... do I need to make a modification or add something to this config?

Thanks
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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That is simply because as part of the circuit, a capacitor is used to store energy. This is primarily used to reduce the ripple on the DC created from AC, but with little to no load, it will do exactly as you describe.

The solution we're suggesting will have capacitors used for this purpose, and will likely act in the way you observe your USB charger does.
 

tomadom

Jan 18, 2013
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That is simply because as part of the circuit, a capacitor is used to store energy. This is primarily used to reduce the ripple on the DC created from AC, but with little to no load, it will do exactly as you describe.

The solution we're suggesting will have capacitors used for this purpose, and will likely act in the way you observe your USB charger does.

Thanks very much for the reply! That's what I was hoping it would do.
 
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