Delete comment from: Ken Shirriff's blog

Ken Shirriff said...

Hi AaronX. I measured the charging current two ways. I put a multimeter in the output circuit to get a simple current measurement. For the voltage/current graphs, I put a "current sense" resistor (a fraction of an ohm) in the output circuit and measured the voltage across it with an oscilloscope. Then Ohm's law gives the current. I used a dummy load rather than a real phone for these measurements since phones have a constantly changing load, which messes up the measurements. And I didn't want to destroy my phone if something went wrong.

Jul 17, 2013, 12:20:36 AM

Posted to A dozen USB chargers in the lab: Apple is very good, but not quite the best