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

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31–40 of 91 posts

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

#31
post #29
post #25

Earlier quoted context omitted.

This appears to be what I purchased, and it looks exactly the same: http://www.frys.com/product/6740515

Just because it looks the same doesn't mean it has the same internals, especially with cheap made-in-China kit.

Wow, really? What if they're all made in China using the same enclosures, does that bring us back to the "check the UL code" method? I know I don't memorize UL codes, so that may be a nonstarter in at least a few situations.

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

#32
I bought up a half dozen Touchpad chargers when they were being cleared out for $5 a piece. I did it mainly because they were the cheapest 2A adapters that work with anything I'd come across, but it's good to know they're efficient and well-built as well.

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

#33
post #18

" Since the designers of the Apple charger went to a great deal of effort to build a high quality charger, I conclude they must not consider voltage sag worth worrying about. Or, more interestingly, maybe they built this sag as a feature for some reason. In any case, the chargers lose points on this." I'm not versed in the arcane arts of EE— could anyone give me a basic definition of voltage sag? And would there be a…

Hi, the author here. I'm using voltage sag to describe how the voltage drops as the load increases. (This has nothing to do with the presence of a battery or not.) Chargers normally are designed to output a constant voltage until the charger hits maximum power. But with the iPhone charger, the voltage is 5.2 volts if there's no load, and steadily drops to 4.6 volts as the load increases. If a device is expecting 5 volts, this could cause problems. Also, charging times could increase since the voltage is lower.

Generally, if the voltage drops under load like this, it's a sign of a poorly designed charger that doesn't regulate well. But since Apple's charger appears otherwise well-designed, it's a bit of a puzzle. One possibility is that maybe the exact voltage input to the iPhone doesn't matter, and the designers knowing this didn't care about the voltage sag. Another possibility is for some unknown reason they deliberately designed the charger this way.

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

#34
post #30
post #25

Earlier quoted context omitted.

This appears to be what I purchased, and it looks exactly the same: http://www.frys.com/product/6740515

I assure you that just because two adapters look the same do not have any relation to the insides. (After all, counterfeit Apple adapters look the same as genuine ones, but you wouldn't think they are the same on the inside after reading this article.) The black plug casing is a common molding style used by many factories - but its the electronics inside that count :) The best way to know if they are identical is to…

I can assure you that as a run-of-the-mill customer, I will likely never check a UL code. I don't know if you get your casings from the same place, putting your own electronics inside, but I feel that if you want to trade on your identity as a purveyor of quality products you're going to have to look at least a little different from bad products. To borrow and twist a line from Seinfeld, "Adjacent to trash, is trash."

http://www.youtube.com/watch?v=KKC5jjFkfgo

I did make the mistake, though, so sorry about that.

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

#36
post #16

The lesson here is that if you don't want to pay for an official apple charger, do not buy a counterfeit one just buy any name brand one with the right wattage rating.

And even with Apple chargers you risk using a charger with the wrong wattage (iPad charger vs. iPhone/iPod IIRC).

But there will be no damage which is more important. My iPad simply slow charges (1A) on my old iPhone & my newer/current Samsung & LG 1A phone charger. Meanwhile my iPad charger works on all my devices - retired iPod Mini, my old iPhone 3G (now iAlarm Clock), Samsung Admire, LG Motion 4G, iPod Touch 7G. In the latter case, charging isn't any faster of course since the devices will only pull 500mA (Admire) or 1A.

The only chargers that I have that won't charge my all of my modern iDevices are old ones meant for iPods (500mA, no signal on the data pins) and my old Belkin iPhone car charger doesn't work with my iPad (Probably only 500mA w/ signal for iPhones. I'd have to check).

Another interesting tidbit: It appears that my car's Pioneer DEH 9400 head unit (aftermarket of course) seems to inform my devices that it can supply 1A of power through its two USB ports. This is the first time I've seen that outside of dedicated chargers and Macs (I assume of course that some PCs do this as well but I haven't seen one yet).

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

#37
post #33
post #18

" Since the designers of the Apple charger went to a great deal of effort to build a high quality charger, I conclude they must not consider voltage sag worth worrying about. Or, more interestingly, maybe they built this sag as a feature for some reason. In any case, the chargers lose points on this." I'm not versed in the arcane arts of EE— could anyone give me a basic definition of voltage sag? And would there be a…

Hi, the author here. I'm using voltage sag to describe how the voltage drops as the load increases. (This has nothing to do with the presence of a battery or not.) Chargers normally are designed to output a constant voltage until the charger hits maximum power. But with the iPhone charger, the voltage is 5.2 volts if there's no load, and steadily drops to 4.6 volts as the load increases. If a device is expecting 5 vo…

It's almost always a balance between cost of manufacture and performance. I would bet money it was not designed that way as a feature.

The interesting points to remember here are:

- USB specifies 5V, not the iPhone

- Voltage drop across the iPhone's internal regulators and charging circuits are probably less than 0.5V

- Most cell phone LiIon batteries are 3.7V

So, presumably they made a charger that allows droop to 4.6V because this is a voltage still capable of charging the battery, yet also allows a less expensive charger design.

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

#38
post #34
post #30

Earlier quoted context omitted.

I assure you that just because two adapters look the same do not have any relation to the insides. (After all, counterfeit Apple adapters look the same as genuine ones, but you wouldn't think they are the same on the inside after reading this article.) The black plug casing is a common molding style used by many factories - but its the electronics inside that count :) The best way to know if they are identical is to…

I can assure you that as a run-of-the-mill customer, I will likely never check a UL code. I don't know if you get your casings from the same place, putting your own electronics inside, but I feel that if you want to trade on your identity as a purveyor of quality products you're going to have to look at least a little different from bad products. To borrow and twist a line from Seinfeld, "Adjacent to trash, is trash.…

ladyada does not manufacture that charger; the website offers it, along with other general-purpose knickknacks, to compliment the main offerings- DIY electronics kits. This last bit is significant- ladyada's run-of-the-mill customer is not going to be your standard Joe looking for a charger for his cell phone.

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

#39
post #11
post #3

This link just wouldn't have been quite as clickable: A dozen USB chargers in the lab: HP is the best .

Its an appeal to the Apple sycophants who troll this web site: "oh no who dares best my beloved Apple?!? I'd better click!"

It certainly appears to have worked, after a fashion. A young article, front page...

Of course, the real question is, who promoted it? The Apple sycophants, or the folks who wanted to rub it in their faces?

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

#40
post #31
post #29

Earlier quoted context omitted.

Just because it looks the same doesn't mean it has the same internals, especially with cheap made-in-China kit.

Wow, really? What if they're all made in China using the same enclosures, does that bring us back to the "check the UL code" method? I know I don't memorize UL codes, so that may be a nonstarter in at least a few situations.

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