[Sprint HTC EVO 4G LTE] KEYofR:
If someone made it, you could use a 100amp port.

The classic description of amps vs voltage to explain electrical properties is water pipes.

A 5000 amp source is a source that is capable of delivering 5000 amps, if you tried to *draw* that much, not a pressure that could blast your device. Think of it as sipping water from a river with a drinking straw. There are millions of gallons of water available if you had some huge pump to suck them all, yet those millions of gallons don't hurt you at all. Not even one little drop goes up your drinking straw unless you suck it. That's like, 5000 amps at 0 volts. 5000 gallons per hour flow rate available, but under 0psi of pressure.

Voltage on the other hand is like water pressure. If you had a tiny 1 millimeter pipe that only had a few drops of water in it, but it was under 5000psi of pressure, those few drops would blast right through you like a water laser. They cut steel plates with exactly such water jets. That's like 5000 volts at .00001 amps. Think static and tazers and gas burner lighters.

You can safely use as high an amp rated usb port, or any other 5vdc source you like, as your phone will only sip one half or one amp* regardless how many amps the source is capable of delivering.

One reason TO use the highest amp chargers you can find is that a charger that could deliver 2 amps, but is only being asked to deliver 1 amp, is only working half as hard as it can. That charger will probably never burn out, it can handle heat better, it can keep up effortlessly when the phone is doing heavy stuff like gps and screen-on at the same time it's charging. Basically to be able to deliver more amps, all the parts in the charger have to be beefier. So it's harder for you to kill them even doing your worst.

*(.5 or 1.0 depending if the d+ and d- pins are shorted by the cord or the port, which the phone uses to detect the difference between a real usb port or a charger. The phone will limit itself to only drawing 1/2 amp from a real usb port on a pc, because that is the spec for actual usb ports, and trying to pull more than that would harm the pc, burn out the usb port on the pc. But if it senses that d+ and d- are shorted, then it knows it's ok to try to draw a full amp.)

Voltage is different. There is some fudge factor room, but I don't recommend feeding your phone more than say 6v or maaaybe 6.5v and don't do that for long. 5 or just a hair over 5 is ideal. I said 5.3 was fine the other day and it is. 6 would probably be ok but might kill the charging circuit after continued use for some time. The higher you go, the sooner the burn out. 7 might even be ok very briefly. Higher and you might actually be ok because it's not uncommon for power circuits to detect out of range voltage and save themselves by cutting off and refusing to accept any power at all unless the voltage is within a set range. But I haven't tested that on this particular phone so I don't recommend trying it :) 4.5 to 5.5 you're fine all day every day.

Lower than 4.5 and you could possibly harm the phone in an entirely different way by drawing too high current. Or it may harmlessly simply not work, not charge the battery, but not hurt anything. Depends on how the charge circuit is made. I won't try to explain _that_ right now!