I want to first say that I am very inexperienced with electronics, I know the basics but that's about it.
I'm wondering if there's any way to charge a laptop/tablet battery with an external USB charger? Specifically an EasyAcc PB18000. It's got a 2.1A and a 1A USB socket, I believe they can both be used at the same time for a total of 3A. The laptop charger runs at 19.5V, 2A. Apparently it's possible to step 5V up to 20V, with a loss in current to 1/4 (I'm aware of V=IR / Ohms law). I've got a couple of questions about this though.
When charging a tablet battery (Sony Vaio Tap 11) is it more important that the voltage matches that of the charger, or that the current does?
Will it damage the battery if either of them don't match?
How exactly would I go about setting this up, would I need to modify the external battery?
Thanks in advance, I hope this is the right place for advice!