Can you use different Voltage and Amps to a charge phone?

Question

If I buy a solar panel that outputs 18 Volts and between 250-300 mili-Amps will it charge my phone? I looked at the charger output for my phone and it is 5 Volts and 1 Amp. I know that Power (units in Watts) = Voltage X Amps. So if 18 Volts X 250 mA = 4.5 Watts (for solar panel)and 5 Volts X 1 Amp = 5 Watts (for wall charger) would my phone charge because you get roughly the same Wattage or does it have to what the charger output says? If I use 18 Volts and 250 mA will my phone get fried? Thank you, I am learning electricity

Answer 1

If you try to charge your 5V phone with 18V, you will FRY IT. NOT RECOMMENDED!

If you regulate the voltage down and try to charge your 5V phone with 5V @ 250~300 mA it will take 4~5x longer to charge vs. the specified 1A.

Yes, there are ways to change 18V into 5V with some boost in current. However such DC-DC converters lose some significant power because they are not 100% efficient.

An 18V @ 300mA solar panel is a POOR MATCH to a 5V @ 1A load. Probably a waste of money. Find a solar panel that is closer to what your load needs.

Answer 2

It is likely that something will break, because it is outside of the specifications, so the circuitry has not been designed for that.

There are circuits that will accept a wide voltage range, output a fixed voltage, and will adjust the current they draw accordingly. If your phone's power input had such a regulator circuit before the battery charging logic, it would work, but this is rather uncommon, because the charger already contains a regulator that provides 5V, regardless of whether it is plugged into a 115V or 230V outlet. If the phone had its own, that would be inefficient.

If you want to charge your phone from the solar panel, you can add a regulator that provides 5V from whatever the panel outputs. Because the power provided by the panel may be less than required to supply 1A at 5V, I'd probably try to find out if there is a way to "slow charge" the phone at 500mA -- it will take longer, but will charge without issues.