USB ???

[devonwoody]

http://www.screwfix.com/c/electrical-li ... electrical


A bit of new technology?

What info or verdict from an Electrical engineer here?

 

[MattRoberts]

I think you'll find they've been around for quite a few years. I've got a couple and they're great

 

[monkeybiter]

+1

 

[Bright-Spark]

Devonwoody

Not that new, just becoming much more common place. The better ones Eg. MK have the USB outlets in a better position and smart recognition of the device for fast changing.
The advantages are that you don’t use up a 13A socket or have to find charger.

I spec a lot of these for offices and even for patients in hospital wards, as in this situation the employer or hospital also don’t have to worry about portable appliance testing of the plug-in chargers.

You can get a good quality i-smart charging hub with more outlets for less money, but this is messier.

At home, we have a USB socket in the kitchen for phones, with a smart hub in the spare room out of the way, for tablets and all the other stuff.

Bright-Spark

 

[devonwoody]

I thought some chargers warn the user to only use charger that comes with equipment?

 

[Racers]

USB is a standard, so anything with a USB plug will have been designed to work to the standard.

Pete

 

[Beau]

Anyone know how much energy these use when nothing is plugged in? Presume there is a transformer in there running 24/7.

 

[MikeJhn]

Less than if you leave your TV on standby.

Mike

 

[Beau]

Less than if you leave your TV on standby.

Mike

I am sure that's true but I don't leave my TV on standby and make every effort to not be wasteful of electricity :wink:

 

[transatlantic]

Anyone know how much energy these use when nothing is plugged in? Presume there is a transformer in there running 24/7.

For one of them it says :

The power input/draw and output of the sockets when no device is connected is < 50mW

So at 12p pKH, thats about 5p a year?

 

[Beau]

Anyone know how much energy these use when nothing is plugged in? Presume there is a transformer in there running 24/7.

For one of them it says :

The power input/draw and output of the sockets when no device is connected is < 50mW

So at 12p pKH, thats about 5p a year?

Ah good man thanks.

Not so long ago these little transformers used surprisingly high amounts of juice when idle.

 

[John Brown]

That's back when they used a simple 50 Hz transformer. Those drew a certain amount of power all the time, regardless of load. Nowadays they rectify the mains to DC, then convert it back to a high frequency, so that they can use a small, ferrite cored transformer, and there is a feedback loop from the output side back to the input side, so that that just enough power goes into the system as is required.

 

[JJ1]

I thought some chargers warn the user to only use charger that comes with equipment?

I stand to be corrected but I was once told that various items are best charged at different rates.
If I remember correctly, it was mentioned that tablets require a higher charging rate than mobiles.
Apparently, a tablet charger will charge a phone ok, but the charging time will be quicker and I presume the lifespan of the battery may suffer in the long run. I've no idea how accurate this information is.

 

[Sheffield Tony]

Like most modern electronics, they are always on and cheap ones are more likely to catch fire. But apart from that I suppose they are convenient.

 

[AndyT]

I'm no electrical engineer, but I have observed that usb chargers are variously rated at 500mA, 1A, or 2A/2.1A.

There is some sort of data exchange between device and charger so that if a device which could be charged at 2A is plugged into a charger that can only supply .5 or 1A, it will still charge ok, but take longer. I think this translates into the advice to charge a high-current device with its own high-current charger.

Conclusion: built in usb chargers, like any other usb charger, will be more useful if they supply 2A than if they only supply .5A, so check the rating of any built-in device.

(There are more subtleties here as well - some multi-socket chargers can supply 2A in total, but less if several devices are plugged in.)

I can see the attraction of a nice tidy built-in, but I can't help thinking that the current standard will be superseded in a few years time, as with any IT-related hardware, and they will need to be replaced, which will be more of a job than just plugging in a new standalone charger.

 

[MikeJhn]

Been a while, but as far as I remember its to do with the difference's between chemistries, NiCad, Ninh and LiIon, Nicad can normally only be charged at approximately 10% of its total capacity if you want it to last, Ninh can charge at a higher rate if it's chemistry can take the higher charge, its to do with the Cathode construction, LiIon have to be balanced charged on each individual cell, if it indeed has more than one cell, unfortunately LiPolymer cells which where the first high capacity cells had a tendency to catch fire if the wrong charger was used additionly whilst burning could supply its own Oxygen by chemical reaction to keep it burning, I have been using all of these Chemistries for a number of years in RC equipment so I got used to the requirement of the different chemistries and their differing requirements for charging, the most modern of these, the LiIon is by far the safest but do need balance charging, to prevent premature failure, this is normally built into the device being charged, bare multiple cells need a special ballance charger.

Mike

 

[John Brown]

"There is some sort of data exchange between device and charger "
In a lot of cases, the "data exchange" is simply a case of the charger applying a particular voltage to either the Data+ or Data- pin(can't remember which!).

 

[themackay]

The first one I bout over a year ago was 2.1 I bought one recently it was 3.1 so should charge quicker

 

[Racers]

Usually the device that's plugged in controls the charging so it doesn't matter how much current the socket can supply.
We are on usb3 standard all backwards compatible so don't worry about future changes USB will be around for a while.

Pete

 

[MikeJhn]

The exchange between the device and charger is the monitoring of each individual cell's voltage and state of charge, to the point of discharging a cell that is drawing too much to equalise it with its partners, this is important to prevent one cell from being charged more than its partners to prevent over discharge of adjacent cells during use, once any of these cells are out of balance it is almost impossible to re-balance them without a more sophisticated charger.

Mike