Tiny, cheap, and dangerous: Inside a (fake) iPhone charger
arcfn.com
arcfn.com
The first indicator that it might be super cheap was the fact that it would transmit on two frequencies; if I recall, those were 88.5MHz and 106.2MHz. "That's strange", I thought, "most North American FM radios won't tune an even-numbered frequency (the .2)."
Once I got inside, I realized the magic. The FM transmitter section was based around a 17.7MHz crystal. 88.5MHz was the 5th harmonic, and 106.2MHz was the 6th harmonic. There was a single transistor that was used as part of the oscillator. "OK", I thought, "that explains the bad sound quality."
Then I started looking closer at the PCB and discovered a few parts that were missing. The scariest was in the USB power section: instead of a 5V regulator (as indicated on the board), there was instead a jumper directly from input to output. That is, it was pumping the noisy, spiky, 13.8V from the car's ignition system directly into the USB port. Luckily, I didn't ever actually plug anything into that port, but it could have gone miserably bad...
Its great to see an in depth article in to the design and the cost-cutting.
(Source - I work at an iPhone repair company)
This article talks about the theoretical danger from an engineering perspective, but I've witnessed these things explode first hand. Definitely heed the advice - get a real charger
Do you have empirical evidence that keeping battery powered devices on chargers has a high enough risk to be concerned? Anecdotes aren't evidence. I once had a UPS go bad and nearly melt down while I was sitting next to it. Should we not leave UPSes plugged in?
I have a smoke alarm installed in the same room, an RCD on the socket and they sit on a solid granite surface!
A few years ago I used to race radio controlled cars - the cells on them taught me a few lessons about how damn dangerous chemical cells are.
Residual-current device: http://en.wikipedia.org/wiki/Residual-current_device
[0] http://www.theiet.org/forums/forum/messageview.cfm?catid=205...
Never cross the street, it might be the last thing you ever do.
Should I be worried and stop charging it overnight? It has become part of my going to bed routine and works well as the iPhone will sync wirelessly overnight but I'd rather not wake up on fire.
I don't know enough about the characteristics of a charger exploding but I'd say the RCD may not be fast enough to prevent the explosion, and that's assuming the explosion is due to shorting to begin with.
The 'uncle' post of your one had some good advice http://news.ycombinator.com/item?id=3904523
http://consumerist.com/2011/11/apple-replaces-frayed-magsafe...
Instead of shopping at Apple, try monoprice.
Edit: I have no affiliation with monoprice. If you downvote, please explain. Is my alternative not helpful?
On the other hand, I've been getting gorgeous, well made XLR cables from them for a great price, and I've never had a problem with CAT 5/6 cables or HDMI cables[2] from them.
Maybe we can say that low price tolerates more variability.
EOM
[1] They dropped those earbuds pretty quickly. I see they again sell an iPhone earbud, maybe it is better. For $2.36 each I'll probably add three to my next order just to see.
[2] Whenever I need a common cable, I generally buy 3 to 6 of them on the theory that my friends and family will have problems that need solving with such a cable. Then I can give them a $3 solution instead of them going to BestBuy and dropping $30.
I bought[1] a brand new mobile / cell phone today. £4.95 ($8 USD) which includes the phone, the battery, and a charger. It's all neatly packed, things in bags etc. it's not on a contract.
So it's possible for huge multinational companies to use economies of scale to make, ship, and sell cheap things.
I'm not so sure that small companies have the same economies of scale - especially for things which require being built to safety standards.
[1] Buying it took about 10 minutes. I can't quite work out how all the people in the chain manage to get paid from an $8 phone.
Of course, once you actually go into the shop and buy it, you find it's the same (unlocked) handset. But because you bought it on, say, O2 instead of Orange, you get it cheaper.
You could make eBay legally liable for missing or faked certifications, but that would basically just force them to cut out a bunch of categories of goods. So they'd get listed under another category etc. etc. I don't think there's a solution to this, and only high profile cases of these things actually blowing up in people's faces and electrocuting toddlers will change anything (probably the legal situation, and probably for the worse). If we're lucky, this doesn't happen before China becomes sufficiently developed to introduce and enforce their own, similar regulations. Of course, production of this kind of stuff will then just move to developing-nation-du-jour.
Meanwhile: Caveat emptor.
Another certification circumvention hack is to import the device as components (which don't require certification) and assemble it in the EU (or US, assuming this hack works there too). Obviously infeasible at that sort of price. A game console maker I won't name here did that with their early devkits for a popular console (maybe they all do it?) to get them to developers quickly. There's no way they would have passed CE certification, as their cases frequently built up a static charge, shocking unsuspecting developers. One even blew up in our office. Nobody told me about that particular work hazard when I took the job...
Here is another one: http://www.youtube.com/watch?v=T88ej64aXUM And a cheap one done right for comparison http://www.youtube.com/watch?v=1F3XlFI1JBo
Man that stung like fuck.
Mine actually blew a cap and melted.
I'd love to see the guts of a REAL Apple charger spilled out for examination next to it.
Tape is a sign of bad design that can be seen a mile away. The cans on the caps underneath are being kept away from the board with tape.
That and the bare lead WTF in it.
That and it's that retarded and dangerous 2-pin design (no ground/earth) that people in the US rely on.
I don't see any tape. This looks like some insulating goo material.
That's a personal anecdote. Not an assurance. You attribute it to "bad design" but that would mean that most or lots of those would "blow a cap and melt". This is not reported.
So it's most probably a faulty unit or a bad run, rather than a bad design. A faulty unit or a bad run can happen even to the most well designed hardware.
At the very least it would mean I won't one day be electrocuted by my power-shower.
To source the same amount of power at 24V, you need ten times as much amperage, 150A, and 1/0 AWG wire, or 8.252mm thick. Much, much thicker, dramatically more expensive, and harder to handle.
And even with 1/0 AWG wire, you'll see a lot of voltage droop between the main panel and the outlet, which will be tens of metres away. A 20 metre run, at 24V and 150A will drop 7.5% of its voltage between the panel and the outlet.
That's why houses that are powered by solar/wind backed up with batteries convert the battery voltage back to household AC, it's not just a convenience, it is also for reasons of efficiency.
Power delivered is Amperage x Voltage, if you want to consume 500 watts at 120V that's a bit over 4 amps which you can do with relatively thin wire, if you want to do it at 24V you'd be using 20 amps, requiring a 5 fold increase in diameter of the wiring! And that's just the beginning, then there are the troubles associated with DC breakers as well as wear and tear on a plug-in system designed for currents that high. Imagine a toaster or a water cooker designed for 24V, you'd need cables thick enough to do double duty as jump-starting hook ups.
Even better would be a standard for 12V at 5A or 10A or something, to power all the other electronics in my house, like monitors, DVD players, etc, that have built-in transformers. But I'm not an EE, so maybe the losses from dozens of feet of low-voltage in the walls outweighs the efficiency gains from having a single large transformer...
The same reason they use very high voltages to transport the electricity and only step it down to 240 as close to the end-user as feasible.
I won't bore you with the physics, but you want to keep the amps as low as possible (which can be done by keeping the voltage high).
I'm a little sketchy on the details (been a while since I studied this sort of thing) but I can personally attest to losing muscle control in my right arm on a 6V circuit using only a standard (1Ah?) alarm battery.
No it definitely isn't.
> There's naught deadly in voltage, it's the wattage that electrocutes you.
In fact, if you want to be precise, it is the current (Amps) that kills you. The reason why 24V isn't nearly as deadly is because at the resistance your skin normally has the current will be low enough that it does not get dangerous.
Up to 48V is considered a 'safe' voltage, but you can definitely feel it and DC is far more dangerous than AC (because with DC your muscles contract and stay contracted so it can be very difficult to disengage from the source).
If you lost muscle control over 6V then likely there were some other circumstances in play, for instance you could have been poking around in a spot where your skin had been breached or you may have had sweat or some other salty solution on your skin.
Real danger starts around 80V for DC and 150V for AC. Yes, you can get electrocuted at lower voltages but you'd have to really work at it.
Most high voltage circuits that you are likely to come in contact with have an internal resistance that is high enough that they can not source a high enough current to do damage, that's why you perceive high voltages as safe. But if a high voltage circuit is beefy enough that it can supply a couple of hundred milli-Amperes you're as good as dead because at that voltage your skin is no longer a strong enough barrier.
On a side note, I think I read women have lower skin resistance than men on average.. Something we were going to do a little design of expirment for in highschool but never got around to completing it because shocking people and playing with electricity was more fun.
Ohh.. According to this men have lower resistance. http://van.physics.illinois.edu/qa/listing.php?id=6793
People love love love to repeat this tired "it's not the volts that kills, it's the amps" line, while completely ignoring the fact that low voltage makes it really, really, really hard to obtain the necessary amps to be dangerous.