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USB cable vs car charger efficiency

4K views 6 replies 6 participants last post by  Jeepeta 
#1 ·
I got a new phone (Droid Incredible) and received car charger with it. It a one-piece charger, not cigarette lighter piece in which USB cable plugs in. The output is 500 MA

On the other hand there is a USB socket in the storage compartment between the front seats - all it needs is USB cable.

Is there any benefit to using car charger vs USB cable? Will car charger charge a phone faster?
 
#4 ·
It's really about the power the USB port is able to provide and the draw the device is able to pull.

For example (no citations so I could be off on these numbers):

The Iphone 3gs can draw ~650ma from the wall charger Apple provides with the phone which will supply up to 1000ma.

Some/many computers and devices with USB ports limit their power to USB2.0 specs which is 500ma so my iphone would not charge as fast connected to a computer (ignoring the fact? that some devices decrease their pull as the charge nears completion).

I'm not sure of what an ipad can pull while charging but it comes with a 2000ma capable power supply... I would guess it probably pulls ~1500ma while using the supplied power brick. Assuming it does, charging it from a computer or other USB port that supplies only 500ma will work but at 1/3 the charging speed.

So back to the Jeep. I'm not sure what rates the 430N or 730RHB provide, however 1000ma (1amp) is called out in the 730RHR specification here:

http://www.wk2jeeps.com/wk2_navigation.htm

It wouldn't surprise me if the 430N and 730RHB supplied 500ma; however my iphone 3gs should charge on the RHR USB port as fast as it's wall charger... but an ipad would only charge at 2/3 rate of its wall charger.

clear as mud?





http://en.wikipedia.org/wiki/Universal_Serial_Bus
A unit load is defined as 100 mA in USB 2.0, and was raised to 150 mA in USB 3.0. A maximum of 5 unit loads (500 mA) can be drawn from a port in USB 2.0, which was raised to 6 (900 mA) in USB 3.0.
 
#7 ·
Try both methods and then decide which one you like best for what ever reason.
 
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