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70 posts

Master Geek


Topic # 104825 21-Jun-2012 10:24 Send private message

I'm wanting to get a new car charger, and currently the standard 1 port chargers won't charge my wife's Iphone 3GS and my old LG GT540 at the same time, so I know it won't handle the S3 instead of the LG!
A lot of the newer car chargers have 2xUSB, one at 1A and one at 2.1A. There seems to be a bit of a difference of opinion on XDA about whether it will damage the phone using a 2.1A feed - I don't think it will as it's only a 'max' value. Also does it need to have the data pins shorted so it will draw more than 0.5A (so phone recognises it as AC rather than USB input)?

I assume the same would go for replacement AC chargers too?

Any input appreciated.

Thanks,
Nick

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Watchmaker Wizard
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  Reply # 644328 21-Jun-2012 15:53 Send private message

I run my Galaxy Note off a 2A car charger, haven't had any problems with it, despite the massive screen, it still slowly charges despite having the screen on, GPS, data, bluetooth and playing audio via the USB interface.

Amperage is maximum available current, doesn't mean the device will actually draw that much. You could hook it up to a 10A charger if you wanted, as long as it was still a clean 12V (or whatever it is) supply, then you'd be fine.

Volts are pushed, current is pulled.




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  Reply # 644344 21-Jun-2012 16:11 Send private message

With USB charging there is supposed to be current limiting in the charger so that there is less voltage drop in the device.

However everything seems to ignore that and just keep on delivering 5v even way past the rated current. That is why most car chargers are still slower than wall chargers.




Richard rich.ms

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  Reply # 644445 21-Jun-2012 20:31 Send private message

You're fine with higher amp chargers.
Whether or not it charges fast or slow will depend on whether the charger has its two data pins shorted, or has a resistor between them etc. Most phones expect the two data pins being shorted as a way of detecting an AC charger, and this causes it to pull more than 500ma of current. Otherwise regardless of the current available, it would pull a max of 500ma like a standard usb port.

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  Reply # 644452 21-Jun-2012 20:44

I use one of these for my Galaxy S2 - http://www.dealextreme.com/p/genuine-griffin-car-cigarette-powered-dual-usb-adapter-charger-for-ipad-iphone-black-dc-12-24v-72687?item=58

My phone detects the 1A port as USB, and the 2A port as AC.

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  Reply # 644629 22-Jun-2012 11:33 Send private message

bignicko: I'm wanting to get a new car charger, and currently the standard 1 port chargers won't charge my wife's Iphone 3GS and my old LG GT540 at the same time, so I know it won't handle the S3 instead of the LG!
A lot of the newer car chargers have 2xUSB, one at 1A and one at 2.1A. There seems to be a bit of a difference of opinion on XDA about whether it will damage the phone using a 2.1A feed - I don't think it will as it's only a 'max' value. Also does it need to have the data pins shorted so it will draw more than 0.5A (so phone recognises it as AC rather than USB input)?

I assume the same would go for replacement AC chargers too?

Any input appreciated.

Thanks,
Nick


Get a 150w  ($69 last time I looked) or 300w (about $100?) DC to AC inverter from DSE or similar. It plugs into the DC power port in the car...and gives you a single AC power point. I then plug in a 4-slot power bar and THEN I plug in any and all items that need their battery charged. If you suck too hard and the battery is being drained in the car, the unit shuts off....and beeps. This may take a couple of hours to reach that point.....and in the mean time your phone, the wife's phone and the kids' iPods have all charged up. 

*MUCH* better option than a single-use car charge that hogs the DC port for a single item. The 150w unit is about the same size as a 500g block of butter. 

I also use it when the mains power goes out in the house. I run an extension out to the car (start the car engine...) and the 300w inverter lets us run several CFL lights and the (mains) phone and Internet router. Max current is 4amps steady ...so you can't use a heater or boil water. I used to plug my UPS into it and then use the UPS to power everything up to 1000w.....thus layering the batteries...which could see me run 8 hours no worries with the mains gone....plus what ever power the car delivered to the UPS to slow the battery drain. 

So many more options and uses than......a dedicated phone charger. :-)




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  Reply # 644644 22-Jun-2012 11:40 Send private message

Ive done that with the inverter in the past but have ended up with issues of getting small shocks off the things that are charging, and blowing up the car stereo when I tried plugging in an aux cable. It was a rental so no big deal tho.




Richard rich.ms

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  Reply # 644650 22-Jun-2012 11:46 Send private message

richms: Ive done that with the inverter in the past but have ended up with issues of getting small shocks off the things that are charging, and blowing up the car stereo when I tried plugging in an aux cable. It was a rental so no big deal tho.


Eeek!!! 

I've never had that. Must have been something in the car not properly grounded. 




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  Reply # 644887 22-Jun-2012 19:22 Send private message

Your dancing with death bro, don't ya know it's not safe to use Galaxy S3 with car charger until they release a firmware update!

http://www.uswitch.com/mobiles/news/2012/06/samsung_galaxy_s3_catches_fire_inside_car/

;-)




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Ultimate Geek


  Reply # 645337 24-Jun-2012 07:56 Send private message

similar question, can galaxy s1 (I9000) travel charger be used with S3 (I9300) ?
Thanks.



70 posts

Master Geek


  Reply # 645673 25-Jun-2012 08:58 Send private message

Thankyou all for your advice. I've ordered one of the Griffin dual 1Amp minis to try as I'm planning on getting 3 in total for all my vehicles.

It's amusing seeing the 'genuine Griffin' dual usb mini charger with a 2.1A USB which look the same as the dual 1A, as the 2.1A ones on the Griffin website look completely different. LOL.

I've decided to go to my default eBay buying mentality - It'll be a knock-off but it'll be 1/4 price.

I won't need a 2.1A feed for a while as the wife isn't getting an Ipad! (for as long as I can hold out)

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