Delete comment from: Ken Shirriff's blog
The votes are all in and "car charger" won for the charger that people are most interested in. Kindle narrowly edged out iPhone 5 at the end. Thanks to everyone who voted; stay tuned for more teardowns.
Anonymous who asked about the oscilloscope probes I used: they are surprisingly expensive Tek P5050
and P6139A probes.
Many people asked about cables. I found an article where someone tested cabled. The quick summary is cheap cables have higher resistance which makes charging slower.
Akshay: sounds like Indian trains have bad quality power. (Why 110V in trains and 220V normally?) It would be interesting to see if higher quality chargers do a better job filtering the power on Indian trains. Next time I visit India I'll bring a bunch of chargers, an oscilloscope, and a train ticket :-)
Anonymous with the step-down transformer: My guess is that using the step-down transformer provides a bit of filtering if the input power is bad (due to its inductance), but it wastes some power in the process. In India, I just plug US chargers into 220V (after carefully reading the label to make sure it will take the voltage). I use a Kensington travel adapter, which converts the plug format, not the voltage.
T_Beermonster: I plugged the fake UK charger into 120V through the adapter mentioned above, which doesn't modify the power at all, so it's just 120V 60Hz into the fake UK charger.
Andrew S: thanks for the info on holograms.
Andsetinn: I probably won't be testing computer power supplies as tomshardware and jonnyGURU cover them extensively.
Nov 7, 2012, 1:43:38 AM
Posted to A dozen USB chargers in the lab: Apple is very good, but not quite the best