I currently have a solar panel (this one), that is able to output 24W of power at peak capacity. I would like to be able to use this solar panel to trickle charge a car battery, but the panel only puts out 2.4A per USB socket and so to get the full 4.8A output out of all three, I would need to tap into at least two of the sockets. Due to this, I don't think that a boost converter would be sufficient as it would only let me use one USB output.

What is the best way to go about doing this without stripping down the solar panel? I would like to keep the panel itself unmodified and instead modify some USBs to plug in and have those converted to 12v output.

I've thought about using a boost converter and a usb Y-splitter, but I'm not sure about the viability of that. I also don't mind how long it takes, as long as it would actually charge it.

  • Note that normally these connectors are just connected in parallel. You could get 4.8A out of one socket if you wanted to. The connectors are designed for 2.4A maximum, so there is a small risk of damaging the connector in exceeding the limit. (If that happens, then you have three connectors, so you can use the other two in parallel...)
    – user253751
    Mar 16, 2020 at 11:21

2 Answers 2


The solar panel in your link is made to charge phones and other consumer electronic and have an output of 5 volts.

To charge a car battery you will need a solar panel of 12 volts or more and to realy charge anything it will need to have an output of 4amps or more.

A solar panel will only produce the rated output for about 8hrs in the middle of the day,so to keep your batteries charged you need to size the panels after this formula amps output times 8hrs=the power you can use each day(this is only valid for the summer so if you are to charge the batteries during winter you need even larger panels).


USB outputs 5V, so I believe you'll find that this panel also only outputs 5V or so. In order to charge your 12V battery, you'll need to find a charger circuit that takes 5V input. I'm sure they are out there but it's going to be some sort of converter type circuit.

  • 1
    for a step up voltage converter you will more than halve the output amps each time you double the voltage. Feb 15, 2020 at 7:00

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