How do you output current..? I know the cellphone will only take what it needs to charge, but let's say I wanted to charge batteries for an example. How would you output let's say 1 Amp ?

So a 26650 or 18650 battery fully charged voltage is 4.2 volts, or pretty damn close to it. Let's say I wanted to charge my high drain, high current 26650 batteries at let's say 1 Amp.. My Efest charger does this already, in fact, it can charge at 1/2 Amp, 1 Amp, and even 2 Amps. I've owned the charger for well over two years or so.

Is it just a resistor that does that? Kinda like how you limit the current with a resistor for an LED ?

How much voltage do you charge a 26650 battery?

How much voltage do you charge a 12v car battery?

Ok, I'm going to take a guess, let it be wrong or correct, using ohms law, 5v, 5Ω, 1A, 5 Watts. So I'd need 5 Ohms to create 1 amp of current going to the battery? That is.. if I'm supposed to use 5 volts to charge a 4.2v 26650 battery. No it's not 3.7v it's 4.2v fully charged.

Anyone care help with this question(s) ?