Why charging at the wrong level could
damage your mobile device
Charging devices not at their optimum charging level has a number of issues.
Firstly, the device won’t charge correctly as designed by the manufacturer. This isn’t ideal for the long-term health of the battery. But more importantly charging will not happen as fast as it could.
Take this iPad example
Requires a charger which is capable of supplying 2.1 Amps at a voltage of no less than 4.97V at the charger connector on the cart/case (when the iPad is connected and charging).
Failure to supply this amount of current at the right voltage will extend the amount of time required to charge the iPad battery. This detrimental effect can be easily demonstrated by charging an iPad, from empty to full, with an iPhone charger. An iPhone charger can only supply the iPad with 1 Amp (referred to as ’1A’).
Why do Amps matter?
Current is supplied by a power supply or charger. A product (e.g a phone or tablet) consumes current. It will try and take as much current as it needs.
Example:
If a product requires 2.1 Amps then the power supply should be able to supply 2.1 Amps or more. If the power supply can supply more than 2.1 Amps this doesn’t matter as the product will only take 2.1 Amps. If the power supply can only supply 1 Amp then either the product will fail to work/charge or charge slowly as it can’t get enough current (or power) to charge the battery. Here charging will take twice as long.
This means it is important to match voltage between the charger and device. It doesn’t matter if the power supply / charger can provide more current then the device requires.
Providing less current will prevent charging or slow it down the same as a poorly designed charger can also prevent charging or slow it down.
See the table below for more information on how mobile phone and tablets charging methods compare.
| Current | Voltage | Power | |
|---|---|---|---|
| 0.5A | 5V | 2.5W | Charging from a computer (USB 2.0). If you’re charging from a computer (USB 2.0 port), the maximum current it can provide is 0.5A. This is much slower than charging from the mains. |
| 0.9A | 5V | 4.5W | Charging from a computer (USB 3.0). If you’re charging from a computer (USB 3.0 port), the maximum current it can provide is 0.9A. |
| 1A | 5V | 5W | Most smartphones come with a 1A charger. |
| 1.5A | 5V | 7.5W | USB Hubs. Supports BC1.2. |
| 2.1A | 5V | 10W | iOS devices and many tablets, including the iPad, require a 2A charger. Some smartphones can also use a 2A charger (e.g. Samsung Galaxy Note II). |
| 2.4A | 5V | 12W | Most iOS devices. |
Power refers to the rate at which energy is added to the battery. It’s calculated by the formula: Power (Watts) = Current (Amps) * Voltage (Volts).