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.