Is there any way for me, without destruction or an oscilloscope, to work out how...

kens · on Oct 20, 2013

There's no easy way to tell how good a charger is just by looking at it. Generally you get what you pay for - if you order a "Genuine Apple iPhone OEM charger" on eBay sent from Hong Kong for $3, I guarantee you it will be a low-quality fake. But a $15 charger from a brand-name manufacturer should be reasonable quality.

Fake chargers will copy the UL marks and labeling, so that doesn't help you. Of course, if it says "Designed by Abble" or "Designed by California", that's a pretty good indication of non-quality :-) (I've seen both of those on fake iPhone chargers - it should say "Designed by Apple in California".)

The one thing people notice from bad chargers is their touchscreens malfunction when plugged into the charger. Bad chargers let through enough electrical noise to overwhelm the very small signals that touchscreens create.

When you say your laptop gets a lot hotter at 110V, do you mean the charger or the laptop itself. Chargers are generally a bit more efficient at 240V than 110V, so I wouldn't be surprised if it is a bit hotter. But the output is exactly the same, so I wouldn't expect the laptop temperature to change. If it's hotter, I suspect ventilation is different or you happen to do CPU-intensive applications on planes.

voltagex_ · on Oct 20, 2013

>When you say your laptop gets a lot hotter at 110V, do you mean the charger or the laptop itself

I mean the area of the case directly above the power input got a lot hotter than usual. This was tested over a couple of hours of the flight while the laptop was running in both high performance mode and the lower power modes

dfox · on Oct 20, 2013

Most people have some idea of how heavy piece of electronics of certain size should be, many fake chargers/supplies are surprisingly lighter than that (sadly, even some known original Nokia and Samsung chargers seem too light to me, so this is not valid test)

Good thing to look for is presence of some name of manufacturer. Absutely no name => unsafe, Obscure or semi obscure Chinese manufacturer => probably OK, Well known global brand => depends (and depends on what the charger is for, nobody is going to manufacture fake Delta-branded charger for iPhone, but fake Delta-branded power bricks for various networking equipment are fairly common).

Power quality on input is certainly an issue, but only for totally out of spec inputs. Small wide input SMPS (like these for laptops) just run hotter on lower voltages because of their internal construction (lower voltage => higher current => higher losses).