Why do some BlackBerry devices need Desktop Manager installed (or the driver) to charge?

Hello Everybody,

In order to get a Blackberry device to charge via USB it requires Blackberry Desktop manager or the driver files (RimUsb.sys and RimUsbNT.inf) to be installed on the PC. I did some research on why BlackBerry devices need a driver to charge and I came across some answers:

A1. "4.x (OS level) BlackBerry handhelds require 500mA to charge. You need to have the BlackBerry device driver (for windows) installed natively for this to work. I dont fully understand what the drivers do, but I think they detect the blackberry and *force* the port to output the full 500ma"
A2. "I could not work out for the life of me how the 2 drivers triggered the PC USB port to charge the Blackberry until now. They trigger a "turn on" supply to pin 2 of the USB cable which the Blackberry Unit sees and turns on its on board charging circuit."

It seems logical to me that a boost in current from the default 100mA to 500mA would speed up the charging process.
Q1. Are both answers 1 & 2 correct?
Q2. What is the difference between the A/C>BlackBerry charger and the PC USB>BlackBerry in terms or charging the BlackBerry device? (I know current would be one of them).
Who is Participating?
ALogvinConnect With a Mentor Commented:
It was explained to me that the AC charger outputs at 500ma, and that USB ports (which were built for data transfer more than power) by default go at 100. USB ports can go higher, but you need a driver to tell it to do that, so it doesnt blow out some unsuspecting device.

I do believe that both 1 and 2 are correct.
SysExpertConnect With a Mentor Commented:
I would imagine that the AC charger already does a 500 ma output and meets the BB requirements for pin 2

USB from the computer is controlled by the USB chipset and there are various settings.

If the newer version require a more sophisticated connection then the driver is needed.

I hope this helps !
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