Can the Nexus 7 be charged on any "normal" cell phone micro USB charger?
The charger included with the Nexus 7 runs at 5Vdc/2A (https://play.google.com/store/devices/details/Addi...) and 2 amps is quite a bit of a power draw.
For USB 1.0 and 2.0 specs, a standard port delivers up to 500mA (0.5A) which my BlackBerry charger is. In USB 3.0, it moves up to 900mA (0.9A). The charging downstream and dedicated charging ports provide up to 1500mA (1.5A).
However, there are plenty of USB chargers that break these specs. Apple’s iPad charger, provides 2.1A at 5V. Amazon’s Kindle Fire charger outputs 1.8; and car chargers can range from 1A to 2.1A.
So where am I going with this? If you use a standard USB (less than 2A) charger, the Nexus 7 will probably charge, but slower than the stock charger. If you were to pick up a charger designed for the iPad or Kindle you would be in a better boat and charging speed would be close (or better in the case of the iPad) to stock.
Hope I helped!
Isn't there a concern for burning out the ac adapter? I know so many fools who have "barrowed" someone else's 13" macbook adapter to use on their 15" macbook pro and overheated or ruined the 13" adapter very quickly simply because they say, "oh it's the same size it must charge it!". (one reason I think sometimes a little differentiation specifically in the magsafe adapter would have helped people, but I digress). Anyway you're right we'll have to see I suppose. Just because the charger that comes with it is capable of 2 amps doesn't necessarily mean that the tablet will actually draw that much I guess right?
I feel like you should be fine on a USB level, but maybe someone else can confirm. Having a device that "can" draw more power than the adapter will provide should not mean it will force more power out.
1) You'll shorten the life of the battery by fast charging it. Not a huge deal on the nexus because it's pretty easy to change the battery yourself worse case.
2) It will take a day and a life to charge.
Apple is doing something different with their chargers because their batteries are either impossible to replace, or damn near impossible to replace. They need to make sure their battery lasts just until your warranty expires.
However, it won't charge from a 4-port Kensington USB power adapter I have, nor will it charge from the iPad USB charger. It will charge (slowly) from the USB port on my Mac Pro and it will charge and seems to charge quickly enough from the Amazon Kindle 3G USB power adapter.
Hope that helps.
NOTE TO GOOGLE: This will drastically limit its use to only one floor in my home — I'm hanged if I'm going to tote that black Asus wall wart up- and downstairs with the tablet. Every other shortcoming in the N7 -- the lack of MHL support and SD cards, for example — seems designed to drive you to Google's play store, to buy streaming media or the (shudder) Nexus Q. I resent those, but understand that if I want a good price, I have to play Google's game But this one mystifies me, unless it was a profit-margin-fattening sop to Asus. If I sound p*ssed about these things, it's because otherwise I really like this tablet a whole lot. If I didn't, I could care less. Google got SO MUCH about this tablet right, that I'm upset about this absurdly simple stuff that's going to trip people up.
UPDATE: I said yesterday I could charge it only with its accompanying Asus unit.
After going through my drawer, however, I have now uncovered a few more chargers that it seems to like. This motley assortment includes my Samsung Galaxy III s converter, my old EVO 4G plug from HTC and a no-name wall-wart that cost maybe 99 cents plus shipping from a Hong Kong vendor on eBay. None of these are rated any higher than 2 amps.
In fact, it merrily charged last night on the Hong Kong unit -- rated only at 200 milliamps!
Yet it spurns ALL the various 10-watt, 2.1 amp chargers I use for our iPads.
I have no idea why. If i can figure it out, I will post.
However, I have a USB battery pack which came with its own cable and the Nexus will charge using that cable from pretty much any USB (presumably slowly!)
I would add a note of caution - I did hear of a guy charge it from his phone charger, it couldn't take the power draw and burn-out killing the Nexus in the process.
I've done a little homework on the apple charger and know that the data lines receive 2v and 2.8v to cause it to limit the charging to 1 Amp (as per www.ladyada.net/make/mintyboost/icharge.html) Interestingly enough once the iPad has received these voltage on its data lines, it continues to charge at the current rate even if the data lines are disconnected.
This unfortunately does not cause the Nexus 7 to indicate it is charging. Though the Nexus 7 does draw some amperage at around 600mA. I have yet to test it while it's off. However if you short the data lines out, it causes it to charge and draw maximum amperage that Nexus 7 wants to take in (or in theory should from what I have seen it has drawn in a little under an amp with no load, it's on but idle.) I have tried putting the data lines to ground with no success, I intend to take a look at the provided Asus charger and see how it operates.
Now even more interestingly, "A simple USB charger should short the 2 data lines together. The device will then not attempt to transmit or receive data, but can draw up to 1.8A, if the supply can provide it." (pinouts.ru/Slots/USB_pinout.shtml). Both the iPad 3, iPhone, and Nexus 7 all respond to this and charge accordingly. I don't recommend doing this as it may draw too much amperage for a supply and burn it out.
And as a last note a lot of charges out there are iPhone/ iPad compatible which is why they won't charge the nexus 7. Sad to say apple has dominated the market for how wall chargers are to be built if they want to work with apple. If I turn up anything new I might post it but I'm already a bit late in the response now.
A small warning out there about cheapy wall warts / AC to DC convertors. While there are a lot of switching convertors out there they all don't necessarily regulated at 5 volts and allow for high current. Please be careful what you use to charge your new toy or as some users experienced their charger can draw too much amperage and burn out a low amperage regulator or IC. This could easily cause a short thus killing the device too.
Well I did some quick digging that I should of done earlier on XDA about the charger issues.
1. Nexus 7 OEM charger is nothing special, just the data pins are shorted.
2. Nexus 7 OEM MicroUSB cable is nothing special. It is a standard MicroUSB cable.
3. Any USB car/wall charger should charge the Nexus 7.
4. Nexus 7 will charge regardless of whether it displays "AC Charging" or not.
5. The charging rate is dependent on the capacity of the charger and the total charging circuit impedance (lower the impedance the better).
6. Increasing the length of the cable increases the charging circuit impedance and decreases the charging rate."
It would appear that the Nexus just happens to be fussy about cable quality.
This is system problem, probably software|hadrware related (Nexus does not want to be FAST charged by not original adapters).
Anyway maybe someone can tell me if it can in fact charge via any old micro usb wall charger or not.
YES & NO. I can't find answers or recipes. Of course, XDA theme says [SOLVED]. ILOL'D. Any good charger allows only 0.8Amps, this is NOT charge, this is only palliative. My maximum from not original charger - 1Amp. But I found one model (of course, this is not final sentence, i think you, people, can find more devices), that supports quick charge @ 1.5Amps!
I try about dozen of devices and now stop my searches...
This is SONY - quick charger EP881.