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Good quality, high-power USB charger? |
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#1 |
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Inactive Member
Join Date: Jan 2007
Location: Dumfries
Posts: 38,495
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Good quality, high-power USB charger?
Looking for a good quality USB charger, preferably from a name-brand, capable of supplying a single output of at least 3 amps or more.
Missus wants a second charger that she can leave at work to charge up her tablet if required. I cheaped-out and bought an unbranded one from eBay which promptly exploded spectacularly when we plugged it into the mains. I replaced it with a Samsung Galaxy charger which claims to have an output of 2 amps (via a single USB socket) and should charge the 10Ah battery in the tablet in about 12 hours but, in use, it takes at least 24 hours so it obviously isn't pumping out the claimed 2 amps. I've had a look around the internet and it seems like the vast majority of chargers which claim to have a high output actually have a whole bunch of USB sockets and it's likely that the specified output is the combined total of all the sockets. What I'm looking for is an after-market charger than can pump around 3 or 4 amps through a single USB socket. From a reliable brand, which won't explode. |
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#2 |
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Forum Member
Join Date: May 2004
Location: Reading
Posts: 27,903
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The Samsung charger you used may well be capable of supplying 2A. But it is the load that ultimately determines how much current is drawn from the power supply.
If the tablet charging circuits use current limiting to regulate the charge current then it won't make a blind bit of difference if the charger is 2A, 3A or 3,000A the current drawn will be fixed by whatever the tablet requires. |
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#3 |
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Forum Member
Join Date: Aug 2010
Location: Essex
Posts: 16,218
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Have a look at Anker chargers on Amazon. I've got 4 of their charges, best I've ever used.
http://www.amazon.co.uk/Desktop-Char...er+usb+charger Also to add, if this is a iPad with a lighting connector then you will need a certified USB cable to get maximum charging speed |
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#4 |
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Forum Member
Join Date: Sep 2003
Location: Sandy Heath, Beds. UK
Posts: 10,378
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What you are looking for may not exist.
The USB 1.x and 2.0 specifications provide a 5 V supply on a single wire to power connected USB devices. A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0. |
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#5 |
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Forum Member
Join Date: Aug 2010
Location: Essex
Posts: 16,218
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Quote:
What you are looking for may not exist.
The USB 1.x and 2.0 specifications provide a 5 V supply on a single wire to power connected USB devices. A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0. I havn't seen the spec but QI quick charge 2.0 used by Nexus, Samsung and others I believe has an even higher capability but you need a compatible charger. The charger I linked to will pretty much charge anything out there except QC 2.0, at maximum speed possible. |
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#6 |
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Forum Member
Join Date: May 2010
Posts: 11,493
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Quote:
Have a look at Anker chargers on Amazon. I've got 4 of their charges, best I've ever used.
http://www.amazon.co.uk/Desktop-Char...er+usb+charger Also to add, if this is a iPad with a lighting connector then you will need a certified USB cable to get maximum charging speed I have a couple of the 40w chargers and a 60w charger (keep an eye out on hukd for offers). They are excellent products. |
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#7 |
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Inactive Member
Join Date: Jan 2007
Location: Dumfries
Posts: 38,495
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Quote:
The Samsung charger you used may well be capable of supplying 2A. But it is the load that ultimately determines how much current is drawn from the power supply.
If the tablet charging circuits use current limiting to regulate the charge current then it won't make a blind bit of difference if the charger is 2A, 3A or 3,000A the current drawn will be fixed by whatever the tablet requires. Course, there certainly might be some incompatibility which prevents the Samsung charger operating at full capacity but that's why I'm looking for a charger that will pump out a high current. Quote:
What you are looking for may not exist.
The USB 1.x and 2.0 specifications provide a 5 V supply on a single wire to power connected USB devices. A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0. Bottom line is that USB chargers now pump out current far in excess of the specifications intended for USB devices. The worrying thing, IMO, is that there's no regulation of cabling. I recently bought a bunch of those "flat" USB cables and, at a guess, I'd say the wires in them are probably of a similar gauge to the wires in a telephone cable and there's no way you'd want to pump 2 or 3 amps through those. The USB cables which came with the tablet, and the Samsung charger, are noticeably chunkier than most USB leads and I'd assume that's 'cos they're designed for higher loads. |
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#8 |
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Forum Member
Join Date: Aug 2010
Location: Essex
Posts: 16,218
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Quote:
The worrying thing, IMO, is that there's no regulation of cabling.
I recently bought a bunch of those "flat" USB cables and, at a guess, I'd say the wires in them are probably of a similar gauge to the wires in a telephone cable and there's no way you'd want to pump 2 or 3 amps through those. The USB cables which came with the tablet, and the Samsung charger, are noticeably chunkier than most USB leads and I'd assume that's 'cos they're designed for higher loads. |
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#9 |
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Forum Member
Join Date: Oct 2004
Posts: 14,638
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What are you actually trying to charge?
If you try to charge say an iPad from a Samsung charger you are not likely to get the best performance, because the charger signals to the device whether it is capable of more than the USB standard 500mA current. Apple does it one way, everyone else does it another way. So an Apple device on a non-Apple charger doesn't necessarily work well as it has no idea that the charger can pump out 2A I've also had some interesting USB cables. They didn't seem to heat up noticably, but they make the connected device take years to charge |
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#10 |
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Forum Member
Join Date: Oct 2003
Location: the wild world web
Posts: 28,132
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Most wall chargers communicate to the device that they ARE a wall charger by shorting the data lines, but I think devices also use varying CHEAP tricks that end up ensuring chargers stick at 500mah when not to requested spec.
The problem is that if the device cannot ascertain the maximum safe power draw then it then defaults to 500mah for safety reasons. Its not all bad, in that for smartphones, defaulting to only 500mah is much better for the battery. |
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#11 |
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Forum Member
Join Date: Jun 2009
Posts: 2,127
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Just to agree with what a coupe of previous posters have said. Anker.
I bought his one a few months ago.http://www.amazon.co.uk/dp/B00PK1IIJ...ker+60w+6-port PS,wile you're at it, I'd pick up a couple of their micro USB charging cables. They are the best I've ever used. |
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#12 |
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Inactive Member
Join Date: Oct 2010
Posts: 6,146
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