How many volts is a phone charger?
You could use a Lightning connector plugged into a computer (via USB), an iPhone charger connected to a wall socket, or an iPad charger connected to a wall socket. A PC USB charger delivers 2.5 Watts of power (5 volts at 500 mA). An iPhone charger delivers 5 Watts (5 volts at 1000 mA).
For mobile phones and other mobile devices like the Kindle that charge with USB, the voltage is typically 5V. A laptop charger might be as high as 20V or 25V. You can usually find the voltage your device needs on the device itself, on the battery, or if all else fails, on the manufacturer's web site.
- All USB cords carry the same 5V, regardless of if it's got a 30-pin head or a microUSB plug, whether it's first-party or third. That means DC chargers are now brand agnostic; if the volts, amps, and connectors are compatible, an Apple wall wart can charge an HTC just as easily as a Samsung.
- First you are right, if the laptop is on charger than charging the cellphone by USB port does not cycle current from the laptop battery. The current comes from the laptop charger and only slows down the rate at which the laptop will recharge. Second case, if the cell phone is charge from your laptop running on battery.
- For mobile phones and other mobile devices like the Kindle that charge with USB, the voltage is typically 5V. A laptop charger might be as high as 20V or 25V. You can usually find the voltage your device needs on the device itself, on the battery, or if all else fails, on the manufacturer's web site.
A USB port can give 500 mA output max provides 5 Volts x 0.5 Amo = 2.5 Watts. With real world efficency losses (nominally 80~90% efficent), you can provide a Higher Voltage with Less Current, or a Lower Voltage with More Current, but you can't create powerout of nowhere.
- It is based on how long a battery will last when power is drawn constantly, e.g. a 2000 mAh battery will power a device drawing 100 mAh for 20 hours. Short for ampere, this is a unit of current, not a unit of charge. It describes the constant and average current that passes through the circuit.
- If you are talking about a USB charger, 1A is enough to charge most devices such as GoPros and Bluetooth headsets and phones, but tablets need 2A. (1A means 1 amp - a measure of electrical current - as others said. In the context of a charger, it means "twice as much" or "twice as fast", if the device can use it)
- "Smart TVs" often have at least one USB port that let you plug in a hard drive, flash drive, or other USB storage device to view media files on your television. Although not every TV's USB port(s) will provide enough power to charge every device, you should be able to charge something.
Updated: 2nd October 2019