Charging Cell Phone on 2 amps?

[fisher99]

Amps and watts and electricity in general is greek to me. I recently installed some 12v USB charging ports in my TT. Each outlet that I installed has a 1 amp and a 2 amp USB port. I know that the charger on my cell phone is rated 1 amp, so I'm wondering if it is bad to charge it on a 2 amp port? Or is it ok and it will just charge faster? My tablet charger is rated 2 amp so I can use that port for the tablet but I'm wondering what damage might occur if someone accidentally plugs a cell phone in there.

[rkresge]

Originally Posted by fisher99

Amps and watts and electricity in general is greek to me. I recently installed some 12v USB charging ports in my TT. Each outlet that I installed has a 1 amp and a 2 amp USB port. I know that the charger on my cell phone is rated 1 amp, so I'm wondering if it is bad to charge it on a 2 amp port? Or is it ok and it will just charge faster? My tablet charger is rated 2 amp so I can use that port for the tablet but I'm wondering what damage might occur if someone accidentally plugs a cell phone in there.

It's easier than you think.

Look at it this way: What you plug into the port is a "load". The port itself can support a load of anything up to the rating of the port. So you can plug a 1 amp device into a 1 amp port, or you can plug it into a 2 amp port, or (if it had one) you could plug it into a 72 amp port. (Ok, that's an exaggeration)

You run into trouble when you connect a load that demands more than the port can deliver, such as plugging a 2 amp device into a 1 amp port. This potentially can cause problems such as blown power supplies or dangerous overheating.

Does that make sense?

Roger

[fisher99]

Originally Posted by rkresge

It's easier than you think.

Look at it this way: What you plug into the port is a "load". The port itself can support a load of anything up to the rating of the port. So you can plug a 1 amp device into a 1 amp port, or you can plug it into a 2 amp port, or (if it had one) you could plug it into a 72 amp port. (Ok, that's an exaggeration)

You run into trouble when you connect a load that demands more than the port can deliver, such as plugging a 2 amp device into a 1 amp port. This potentially can cause problems such as blown power supplies or dangerous overheating.

Does that make sense?

Roger

Yes, that actually does make sense. Even to me! So my concern was actually backwards. No problem plugging a 1 amp cell phone into the 2 amp port, but probably best not to plug my 2 amp tablet into the 1 amp port. Very interesting, and MUCH appreciated!

[WYRon]

Originally Posted by rkresge

It's easier than you think.

Look at it this way: What you plug into the port is a "load". The port itself can support a load of anything up to the rating of the port. So you can plug a 1 amp device into a 1 amp port, or you can plug it into a 2 amp port, or (if it had one) you could plug it into a 72 amp port. (Ok, that's an exaggeration)

You run into trouble when you connect a load that demands more than the port can deliver, such as plugging a 2 amp device into a 1 amp port. This potentially can cause problems such as blown power supplies or dangerous overheating.

Does that make sense?

Roger

I agree with your logic when it applies to normal electrical circuits. If you plug in an appliance that draws 20 amps on a 15 amp circuit you'll blow the breaker. For USB, however, that will not be the case. There is internal circuitry to only deliver the maximum current available. That means you can safely plug in a tablet that "wants" 2 amps into a circuit only able to deliver 1 amp. You just charge slower. For example, that is effectively what happens almost every time you connect your tablet to a computer.

[fisher99]

Thanks, gentlemen, for the replies. It's no wonder this electrical stuff is confusing to me...

[smiller]

And it just got more confusing with Quick Charge 2.0 and 3.0 available on newer phones... the charger and phone negotiate a voltage (up to 12 volts, to pass more current on skinny charging cables) that changes as the charge progresses. Up to 25 watts, works great, flat to full charge in 30-45 min!

These aren't your father's chargers