Power Basics Watts

Power Basics, Part 4 – Knowledge is Power (Watts)

Everyone’s heard of Volts, Amps and Watts, but most of us don’t know the first thing about them – here’s a basic understanding of electricity’s key players, one piece at a time.

Knowing what volts, amps and watts are doesn’t do you much good unless you understand how to apply them, so we explain how you can use this info when purchasing electronics. When it comes to the volts and amps of your portable device and its charger, there are a couple simple but essential rules:

  1. The voltages must match! Remember from previous posts that voltage is like electrical pressure; you need to have a voltage in order to move your charge. Well when you’re charging something, like a laptop or a cell phone, the voltages have to match between your device and the charger. A charger that has a smaller voltage than your device would be too weak to deliver charge efficiently. A charger that has a larger voltage than your device would be too strong. A too-weak or too-strong voltage will do damage to your device and your charger.
  2. The amperage of the charger must be greater than or equal to that of your device. Your iPad, for example, is a 5V/2A device. When you charge your iPad, you should always use a charger that has a max output of 2A or more – any less and you’re putting a lot of strain on both your iPad and your charger. Ever notice how hot your iPad gets when you try to use your iPhone charger to fuel it back up? That’s because your iPhone charger has a maximum output of 1A, and your iPad is constantly trying to pull 2A out of it. You should also know the device you’re charging will always determine the amperage coming out of your charger – not the other way around. If you connected your iPad to a 10A charger, it would still only charge at a rate of 2A, because that’s programmed into your iPad. Your charger cannot push a higher amperage into your device – only your device controls the amperage.
How are you supposed to know the charger’s amperage and voltage? It’s always written on the charger. Ever notice the small, fine print on your cell phone charger? It’s on your laptop charger, too. It’s actually on every charger you own. Just look for the OUTPUT rating – it will always have the voltage and the amperage recorded. The charger that comes with your device will be rated for your device’s exact specifications, i.e. the output of your charger will always match the input of your device.
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