Tiny, cheap, and dangerous: Inside a (fake) iPhone charger(arcfn.com)
arcfn.com
Tiny, cheap, and dangerous: Inside a (fake) iPhone charger
http://www.arcfn.com/2012/03/inside-cheap-phone-charger-and-why-you.html
67 comments
Interesting point. I've seen plenty of customers bring in damaged iPhones with damaged motherboards or charging ICs who have been using their devices with non-branded chargers sourced from the likes of eBay. Most people seem to be happy saving a few dollars on a charger for an expensive phone!
Its great to see an in depth article in to the design and the cost-cutting.
(Source - I work at an iPhone repair company)
Its great to see an in depth article in to the design and the cost-cutting.
(Source - I work at an iPhone repair company)
really? Not even a voltage divider? That would kill anything plugged into it right quick
I would not be surprised that most USB devices will actually survive that without any damage. It's usually not possible to use USB's roughly 5V directly (because it's not actually reasonably exact 5V and modern logic often uses lower voltages) and thus most devices contain some kind of switchmode power supply (linear regulators essentially cannot be used due to strict input current requirements of USB specification) that tends to be designed to work up to input voltages of tens of volts.
One day at work I watched a coworker's fake phone charger explode in a literal fireball that went off with a large "bang!" complete with shrapnel, flame shooting out and good amount of smoke.
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
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
I had a genuine Nokia-charger go total armageddon on me once. Never charge your phone while you sleep, it might be the last thing you ever do. Regardless if it is "fake" or "genuine".
You could say this about having any electronic devices plugged in when you're not observing them. It's not practical.
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?
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 charge my devices overnight.
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.
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.
For the Americans an RCD is the same thing as a GFCI, it's also called an ALCI in some places.
And still all three acronyms are totally meaningless to me.
Residual-current device: http://en.wikipedia.org/wiki/Residual-current_device
Residual-current device: http://en.wikipedia.org/wiki/Residual-current_device
I'd think an arc interrupter would be better.
Surprisingly difficult to find an arc interrupter in the UK. I found a link [0] which might shed some light on that; essentially the characteristics/problems of a 240v grounded system are different to a 110v, predominantly 2-pin system.
[0] http://www.theiet.org/forums/forum/messageview.cfm?catid=205...
[0] http://www.theiet.org/forums/forum/messageview.cfm?catid=205...
You need both to prevent fire and accidental shock. Fortunately, you can install both at the same time for all of your receptacles by using GFCI+AFCI circuit breakers. Unfortunately, they are expensive.
All true, and also: GFCI breakers will not substitute for the dual breakers used in many panel boxes, they are too big. And, use of GFCI breakers is not compatible with three-wire circuits used in many locales in the US, at least. (What I mean is, two hot wires of opposite polarity sharing a common grounded conductor, allowing to run two circuits over three wires.)
> Never charge your phone while you sleep, it might be the last thing you ever do.
Never cross the street, it might be the last thing you ever do.
Never cross the street, it might be the last thing you ever do.
[deleted]
I always used to charge devices while I slept (and the plug is pretty close to my bed). Then a few weeks ago my MacBook magsafe adapter literally burnt through the insulating material and the metal wires. Fortunately it happened during the day so I could react to it, but needless to say I won't be charging anything over night again!
I charge my iPhone at night using the genuine Apple charger. As far as I'm aware it is grounded (UK) and I have one of those RCD type things for the whole house, as well as a fuse box.
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.
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 think the main hazard is fire, isn't it? Both the RCD and the earth connection are to stop humans from being electrocuted if they are touching the circuit while it shorts.
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
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
Correct. You need an arc-fault circuit interrupter for that.
I was using a grounded UK charger too when this happened (although it was Mac not iPhone). I think the chances of this happening with high quality electronics is pretty low but as far as I know the Fire Service recommends unplugging all electronics at night so it's probably not necessary but obviously the safest solution.
Errrr, If that's true then it's astonishingly unacceptable. (I mean - official chargers should never be dangerous.)
It was a big enough deal that Apple was sued, and gave away free replacements.
http://consumerist.com/2011/11/apple-replaces-frayed-magsafe...
http://consumerist.com/2011/11/apple-replaces-frayed-magsafe...
Thanks for linking to that report, I didn't actually know about that. I brought mine back and as soon as they saw it they replaced it. I think any company would have replaced it to prevent bad publicity, there were visible burn marks on it.
Well they did have that problem with some batteries that were recalled
http://news.bbc.co.uk/1/hi/6945593.stm
http://www.pcworld.com/article/140101/cell_phone_battery_exp...
Oh, the irony of an article with an Amazon ad on the side for an Apple USB Power adapter accompanied by reviews with such titles as "This is NOT and OEM Power adapter" (4 days ago)
Cheap doesn't mean it has to be dangerous, that's a false dilemma.
Instead of shopping at Apple, try monoprice.
Edit: I have no affiliation with monoprice. If you downvote, please explain. Is my alternative not helpful?
Instead of shopping at Apple, try monoprice.
Edit: I have no affiliation with monoprice. If you downvote, please explain. Is my alternative not helpful?
I use monoprice for many cables. But their knockoff iPhone earbuds of a few years ago were disasters[1] and their iPhone charger cables haven't lasted well.
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.
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.
> Cheap doesn't mean it has to be dangerous, that's a false dilemma.
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.
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 $8 phone.
These cheap pay-as-you-go phones are subsidised by the network--normally, you have to buy at least a £10 topup to get it, and if you look at the website of a phone shop like Carphone Warehouse, you'll find the exact same phone listed at different prices on different networks.
Of course, once you actually go into the shop and buy it, you find it's the same (unlocked) handset. But because you bought it on, say, O2 instead of Orange, you get it cheaper.
Of course, once you actually go into the shop and buy it, you find it's the same (unlocked) handset. But because you bought it on, say, O2 instead of Orange, you get it cheaper.
Yeah, I was buying a budget phone recently. They are about £10-£30 cheaper locked to a network.
You can build the gut's of a basic phone using well under 1$ worth of electronics (speaker/microphone/processor/antenna/and a little storage) and a simple antenna. After that it's battery, case, display, charger, packaging and assembly which can go up and down the cost/quality map, don't have to cost much individually. It's the same reason you can have those key-chain games with more processing power than a Ti-86 calculator for 3$.
One obligatory warning: oftentimes the cables are older generation or may not support all features. Especially with the mac cables (e.g. thunderbold/minidisplayport)
The article is very well written but I don't like the use of the word 'fake'. It is not 'fake' unless it pretends to be something it is not (like if it was actually pretending to be produced by Apple, or be produced to standards it was not). It may be cheap and nasty, but what would you say if a company that wasn't Apple produced a fantastic and superior charger? Would that be a 'fake' too?
Wow. These chargers may literally kill you. Where are U.S. regulators? Where the heck is eBay?
CE and UL certifications get checked on import as far as I know. At $2.79, I doubt the author paid any import duty, so the parcel presumably never even went through the relevant office. I doubt regulation on such parcels could be done cost-effectively, it's probably more realistic for eBay to alert users to the problem. But then eBay might lose out on a bit of business and also, the manufacturers probably would get wise to it and print fake UL and CE logos on the device. And even if you educate people on the issue, a 90% lower price will be very tempting for many.
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...
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...
UL is an independent safety lab that has no connection to the US government. US customs has no obligation to check if an incoming item is UL-approved. It's up to the consumer to look for those labels. Obviously counterfeit markings are a problem, that's why you now see more secure UL labels including hologram labels and other tricks.
CE markings are generally worthless. There is no certification process for it, importers are free to stamp it on everything. It basically just says that they believe it to be safe, and thus take some responsibolity. And of course if you are importing the device yourself, you are the one taking the responsibility.
There is a lot of good quality stuff that comes out of China but equally there are people happy to risk our lives for a bit of profit. Some of this stuff clearly doesn't meet safety standards and shouldn't be in sale.
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
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
That's fascinating... as someone doing Physics it's possibly useful, too. Thanks!
I will say I got a nasty zap off a fake Lenovo charger a couple of years ago. The mains power cable had fallen slightly out, resulting in the earth pin not contacting. The device had a short between neutral and ground thanks to piss poor design and construction.
Man that stung like fuck.
Man that stung like fuck.
Having owned an Apple Airport Express, I can assure you that it's just as dangerous and badly designed.
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.
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.
Thanks - looks horrid inside :)
What exactly looks "horrid"? Looks like a fairly standard professional circuit, with plenty of good insulation...
Tape.
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.
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.
Well, the neutral wire is connected to earth. Grounding is important for metal cases, but when your case is an insulator (plastic), it's less important. If the hot wire comes loose and touches the plastic case, it's not going to harm you, which is what grounding protects against.
>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.
I don't see any tape. This looks like some insulating goo material.
I don't see any tape. This looks like some insulating goo material.
>Having owned an Apple Airport Express, I can assure you that it's just as dangerous and badly designed. Mine actually blew a cap and melted.
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.
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.
I had a HP-laptop charger that developed a screeching noise -- it sounded like a slow-rotating fan that could use some oiling. It didn't explode, but it caused the laptop to crash hard a few times (the screen just got garbled) and, needless to say, didn't provide the power required to charge the batter.
That charger isn't even small. If you take a look at some of latest Braun and Nokia chargers those are much smaller. (I'm sure there are many other manufacturer using these chargers that aren't larger than ordinary euro-socket). Actually Apple chargers are HUGE if we consider latest development trends.
I had one of these and the touchscreen on my phone while charging was indeed unusable, as he warns can happen. I almost wrote off the phone as broken before I realized what was causing the problem...
I would love to have my house wired with 24V (instead of 240V).
At the very least it would mean I won't one day be electrocuted by my power-shower.
At the very least it would mean I won't one day be electrocuted by my power-shower.
A 240V mains socket (depending on jurisdiction) is expected to provide 3.6KW. That requires 15 amps of current, and (here in America) 14 AWG wire, 1.628mm thick.
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.
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.
The reason why you don't really want that is because the line losses over even very short runs of copper wire at those voltages are huge. You'd need extremely thick wires (costly) to deliver usable power.
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.
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.
I just wish there was a way to get 12V & 5V at ~1A in addition to the 110V outlets in my house, supplied by a large transformer in my basement. That way I could avoid wall-warts for all my electronic devices like my router, usb hub, phone charger, etc...
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...
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...
This is a start: http://www.engadget.com/2009/12/05/10-usb-power-outlet-leave...
Unfortunately, it's a crapshoot to find outlets that don't leak power. Look for the ones with a mechanical switch to disconnect the USB ports.
You'd lose a lot of energy in the cables in the walls of your house that way.
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).
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).
It is perhaps worth noting that 12/24V DC is just as deadly as 120/240V AC. There's naught deadly in voltage, it's the wattage that electrocutes you. A static shock is 6kV, as I recall, but the amperage is low enough that it doesn't hurt at all.
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.
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.
> It is perhaps worth noting that 12/24V DC is just as deadly as 120/240V AC.
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.
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.
I recall an apocryphal story of a guy who got killed by a 12V car battery. It was a hot day, and he was trying to pick it up, but it was heavy, so he was using a couple of pairs of Vise-Grips. On the terminals.
In my experience the overlooked risk is burns. People think low voltage dc is safe(er) (no electrocution) because of high skin resistance, and are amazed when there are a shower of sparks from a car battery (when something goes wrong like a tool falling across the terminals). In high school I did welding with capacitors that looked like pyrotechnics using a butter knife fom the cafeteria.
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
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
Short the terminals of a 9V battery with your finger. Now unscrew an outlet cover and short the terminals within with your finger. Notice the difference. (Note: don't actually do the second one.)
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.
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.
I agree entirely. Nonetheless, here's an interesting story about someone being killed by 9 volts: http://www.darwinawards.com/darwin/darwin1999-50.html
It's interesting both because 9V killed the guy and because he had to try pretty hard (stabbing his thumbs) to achieve it. So, while dangerous, not nearly as dangerous as e.g. 110VAC.
This is why I always buy expensive, good quality car chargers. I went through one every few months until I got my last one. Still going strong after 4 years.
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...