Poundland are doing a little cable with USB at one end and five connections the other end to connect to a variety of different Smart Phones. So you can charge your phone from your laptop.
Would the voltage likely be *steady* enough not to damage the phone with 'spikes' ?
They also do an adapter to plug into the car cigarette socket with a USB femail socket built in. This will then accomodate the first mentioned lead.
Would the cigarette socket also be likely to 'spike' and damage the phone?
Well if they were dangerous, they should come with a warning, but if they start blowing up phones, even at the price you would probably have a claim against the shop if there was no warning. Brian
USB ports on laptops generally only provide 0.5A, divide that 0.5A between five devices and it wouldn't go far, so presumably it has five different types of connector and you pick the one that fits the phone?
Modern phones will take up to 1 or 2A, so charging will be slow, some phones won't stoop that low and will refuse to charge at all.
Provided the phone wants 5V (which is what USB provides) the supply is regulated for the innards of the laptop anyway.
No, it'll be regulated from the car's nominal 12v down to 5V.
The laptop would be damaged by voltage spikes too - so yes.
I doubt it, but this is *slightly* more dodgy. It depends on your car electrics. High quality adaptors would have plenty of smoothing to remove any spikes.
... but you probably don't get high quality for £1
this is less certain. There are electronics out there that dont survive or protect against the transients that are sommomnish in vehicles. I've no idea about poundland's specs.
The multi-connector is just a splitter - if you get any spikes, they're coming from the laptop.
The specification is pretty tight: 5V @ 500mA - reasonable to assume you can only charge one gadget ar a time.
The car adaptor obviously has some kind of voltage regulator to drop the 12V down to 5V - at £1 you can afford to break one open and describe to us what's in it so we can give better informed advice about any potential risk.
I have no personal experience of this, however....
Charging a Smartphone from a USB socket on a PC or Mac is completely normal. There should be no voltage spikes as the power output from the USB socket is designed to power external devices. The real question here is whether a single USB socket can supply enough current to charge five Smartphones at once in a reasonable time.
No. The adapter will contain electronics to reduce the voltage to what is needed by the phone and will regulate it.
The cigarette lighter socket plug on the connector for charging my non-smart Nokia mobile has on the label:
Inoput: DC 12V/24V Output: 5.7V 800 mA
The mains adpater for charging that phone has an output of 5.3V DC.
It's only a dumb cable - the voltage comes from the laptop. The laptop's USB output should be regulated to 5v - so it won't damage the phone. Just mightn't charge it as fast as a dedicated charger 'cos the laptop's USB will likely only supply 500mA.
No, it will be a regulated DC to DC converter to produce 5v from the car's 12+ volts. Very likely the same innards as those sold by the likes of Maplin at several times the price.
I think the point is whether a £1 charge adapter is safe to use on say; a £100 smartphone for instance.
If it uses a series pass transistor in the regulator, there's always a possibility the transistor could fail short-circuit and dump the full 12V on the USB connector.
If the target device uses a lithium battery, a fault condition of 12V on the USB connector could overwhelm the charge control chip and cause overcharging - overcharged lithium cells tend to get thermal runaway and vent with flaming gas!
How many corners did they cut to get it on the shelves at that price?!
They probably do not. Some of the "quality" branded 12V/5V adapters for the car are so small there is no room for anything large.
It will be a switched mode converter using a commonly available chip that cost pence.
As already stated the current available from a USB lead connected to a computer/laptop will be limited and the capability will be charging one phone at a time. Even from a 12V/5V converter for the car probably it will be limited to charging only one or two devices at the same time.
I suspect that is not its intended purpose. As another poster has commented, it is more likely to be designed to allow connectivity with different devices.
I'm sure that's true but I think the point of the question is whether a device that costs £1 will be up to the job.
I bought a USB SD card reader from Pound World but it failed after a few weeks. I bought another one but that failed too. I think if you plug and unplug the whole thing from the computer it is OK but it doesn't like the card being inserted or removed when the reader is powered.
Had a look a couple of weeks ago, they also sell USB phone chargers that plug into the mains. Of course these are safe. Only a quid.
So I spent a while in the shop thinking I'd buy one to take to bits out of morbid curiosity, but then I spotted a bag of 'spicy crackers' that probably rates higher in the morbidity for a pound sweepstake. So I bought that...
Hmmm, WiFi doesn't permeate too well here 6 feet down. Am I getting out?
In any computer, the 5V rail the USB supply comes from is capable of at least several amps, without short circuit protection, a mishap could result in melted copper tracks on the motherboard.
The arrangement in a car adapter is a little different - and there's various ways of going about it depending how cheap they want to make it.
Possibly the best way is with a switch-mode chip like the industry standard MC34063 - whether you'll get that for a £ is another matter.
Next time I go into town, I might punt a £ for one just to break open and see what's in it.
Not just any computer MoBo, only PC Chips MoBos ime. Even here they do add a safety fuse in the form of either a very thin circuit trace or an smd inductor, not items you'd normally class as a fuse but, at 5 volts, good enough to stop a conflagration.
However, the downside of this one shot fusing protection is that all the USB and PS/2 sockets lose their 5v rail (keyboard and mouse stop working). I should know 'cos I've bridged a few burnt out inductors/cct traces with a 3 amp polyfuse on these s**te MoBos (after clearing the short cicrcuit, usually a vandalisedd USB socket from which I've snipped the offending pin).
With every other brand of MoBo I've seen, the standard practice is to completely forego the USB negotiation for current protocols and simply wire the +5v pins to a common bus protected by a 3 or 4 amp polyfuse. IOW, your 2 or 3 amp usb charger is unlikely to be kept short of juice when plugged into a desktop PC.
A laptop, otoh, probably does include the full power control protocol to minimise excessive demand from its battery (but, even here, this may not always be the case).
With a limit of just half an amp output, the chinese manufacturer will be able to get away with mounting the chip straight onto the circuit board with a blob of protective epoxy to stick it down to the board (just like those cheap USB flash memory card adapters).
They only have to survive 6 to 12 months before atmospheric pollution poisons the chip and the punter has to...well, punt another quid their way. Most Pound shop customers wouldn't bother invoking SOGA over a one pound item. The Pound shop management rely on this factor but aren't stupid enough to open this can of worms so will cheerfully accept any warranty returns with good grace.
If the chip turns out to be under a blob of epoxy on the circuit board, I'd be a little leary of such a product in this case.
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