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JoeSchmoe007 02-25-2011 07:33 PM

USB cable vs car charger efficiency
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?

jwojcins 02-25-2011 10:15 PM

Re: USB cable vs car charger efficiency
I'm pretty sure my phone charges way slower when I have it plugged into the USB vs. the cigarette lighter charger. However, I usually use the center console USB because I like to have my phone hidden away instead of flopping around the cup holders.

Radside 02-26-2011 06:46 AM

Re: USB cable vs car charger efficiency
I use the cigarette lighter in the center console for my phone and the center console USB for my iPod.

PigNib 02-26-2011 08:17 AM

Re: USB cable vs car charger efficiency
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:

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?
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.

Megatron 02-26-2011 08:21 AM

Re: USB cable vs car charger efficiency
Some interesting information here.

You made a good choice, I have a droid incredible and it does well (minus the somewhat poor battery life, unRooted btw)

PigNib 02-26-2011 08:48 AM

Re: USB cable vs car charger efficiency
Which radio do you have Joe?

Jeepeta 02-26-2011 09:31 AM

Re: USB cable vs car charger efficiency
Try both methods and then decide which one you like best for what ever reason.

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