Max safe amps for car charger in us?

pcguys

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I don't want to fry my S3 or cause a car fire!

Do they make ones with max amps that can charge two S3 phones at once? (max amps to both at same time?)

Thanks!

Sent from my SAMSUNG-SGH-I747 using Tapatalk 2
 

jcp007

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At 2.1 amps, that's going to be a quick charge. Can the GS3 handle that much current as the OEM is, I believe, a 700 mAh.
 

sparksd

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jcp007

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pcguys

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With a standard USB data cable the phone recognizes it as a USB charging source and only pulls 500 mA. You can get "charging only" cables allowing higher (still safe) amperage --

Amazon.com: Naztech Micro USB Charging Cable - BlackBerry, Cal-Comp, HTC, LG, Samsung, Nokia, and Sony Ericsson: Cell Phones & Accessories

Dave

OMG: Dave made a huge point here: I always bought usb sync/charge cables because I figured they were the same price, why not have the extra versatility of being able to sync too!

OK. I'll definitely get the charging only cables so I'm able to get more than .5 amps.

Now the only question remains is if it will fry my new S3 at 2.1 amps.

If 2.1 amps is fine, why did Samsung only ship with .7 amps? (Wouldn't they want their devices to charge as quickly as possible if there were no downsides?

Thanks again Dave!

Mike
 

pcguys

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Is the answer that the phone only sucks .7 amps, so any more on the charger side would not be used?

Is that why you can safely charge an iphone with an ipad charger? (the phone only sucks as much as it wants)?

(I do recall that you may NOT plug an ipad into an iphone charger because the ipad will suck too much power and will overload the iphone charger.

Mike
 

pcguys

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Wait a second: isn't the charger that came with the Galaxy S3 a charge & SYNC cable which plugs into the wall adapter? If all this is true, shouldn't the charging from the wall be a slow .5 amp (usb speed)? It seems MUCH faster than that.

What am I missing?

If it's the cord that determines the rate, how could I be getting fast charges from the provided cord plugged into the wall adapter?

Mike
 

camiller

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Wait a second: isn't the charger that came with the Galaxy S3 a charge & SYNC cable which plugs into the wall adapter? If all this is true, shouldn't the charging from the wall be a slow .5 amp (usb speed)? It seems MUCH faster than that.

What am I missing?

If it's the cord that determines the rate, how could I be getting fast charges from the provided cord plugged into the wall adapter?

Mike

For a wall/car charger the data pins may be shorted together internally, so it doesn't matter what cable you use. If a generic wall/car charger is designed for the iPad, it uses Apples weird way of signalling to the device that it can draw full power. Instead of shorting the data lines Apple provide a specific voltage on the data lines (2.0 or 2.8 volts IIRC) to tell the device how much voltage it can pull. By using a charging only cable you are tricking the device into drawing maximum power.
 

pcguys

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Sorry for being slow on this, and ignoring the iphone/ipad issue for the moment:

If a charging-only cable tricks the phone into drawing maximum power, then how does the stock charge + sync cable provided by samsung charge faster than USB (since their cable is a removable USB cord)??

Mike
 

sparksd

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I took a look and using the Amazon dual-port 2.1A charger I referenced above, my S3 battery status says Charging (AC). Using the same cord but plugging into a laptop USB port, it says Charging (USB).

Dave
 

pcguys

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For a wall/car charger the data pins may be shorted together internally, so it doesn't matter what cable you use..

Having re-read this thread again, it sounds like CaMiller's point is important:

A fancy wall or car charger can be designed in such a way that it doesn't matter if you use a sync cable vs. a charge-only cable).

Mike
 

camiller

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Having re-read this thread again, it sounds like CaMiller's point is important:

A fancy wall or car charger can be designed in such a way that it doesn't matter if you use a sync cable vs. a charge-only cable).

Mike

Right. But it is important to re-iterate that if the wall or car charger is made for/targeted at Apple devices (which for some unfathomable reason seem to be popular ;) ) an Android device is likely to see it as USB instead of AC.

So if the advertising copy says it charges your iPad and Android devices, it most likely will charge the Android device at the slower rate.
 

snork

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I use a 2.1 amp USB charger in my car and my s3 has been fine.

All chargers these days (unless you buy some POS for 50 cents) trickle the last bit so you dont overcharge and thus ruin your phone.

and FYI, the stock charger that came with the s3 (at least on Verizon) is a 1 amp charger.
 

pcguys

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Right. But it is important to re-iterate that if the wall or car charger is made for/targeted at Apple devices (which for some unfathomable reason seem to be popular ;) ) an Android device is likely to see it as USB instead of AC.
.

Now I'm feeling really dumb:

Since I do have an iPad also, if I got one of the car chargers that mention iPad, but use a charge-only cable, will my android still charge slow?

Mike