both have the same miniusb connector so does that mean i can use 7290 charger to charge V3 phone? Physically the connectors are compatible but what about voltage and wattage and all that stuff? Anyone tried it?

Thank you.

All USB chargers use the same voltage (5 volts). If it is a USB charger, it's safe to try. A charger is a USB charger if it has a USB connector (either mini USB connector or a full size USB connector)

Amperage (current) is a different story (100mA vs 500mA), but they all err on the 100ma side unless automatically negotiated to output 500mA. Some USB chargers are intelligent (auto-negotiation circuitry) and some USB chargers are 'dumb' (just a 5V adaptor that happens to have a USB connector. Even for the unregulated USB chargers, due to Ohm's law, the fixed voltage limits the current to the charging capacity of the device.

The 'dumb' USB chargers will simply charge a BlackBerry 7280 very slowly, since the 7280 seems to prefer to auto-negotiate before it wants to accept the full current (500ma instead of 100ma). At least, that has been my experience with using an off-brand charger with my 7280.

The bottom line is that it's safe to interchange USB chargers with different devices -- but be prepared for slow charging on certain devices that like to err on the safe side. (This does not always happen)

Just adding my own experience here...

I normally charge my 7250 through USB on my laptop (w/ Desktop Mngr installed).

I have left my laptop at work lately and my BB is running low, so I have started to use my PC (w/o Desktop Mngr installed) with the same USB cable and it takes quite a bit longer for the BB to fully charge.

I would say it takes 2-3 hours to fully charge through my laptop but it takes at least 5-6 hours going through my PC.
Both computers have USB 2.0, if that would make a difference or not.

I had assumed it was because the BB software was not loaded on my PC.

anyone comes across this problem? does it means its still charging but slower? noticed this problem on some pc usb port too esp when the Desktop manager s/w is not installed.

from what i have experienced, our BlackBerries dont charge at all when they are plugged into a computer without the blackberry software, even though it has the little lightning bolt on it.

i have a patch that i put on some of the users computer that tells the computer its a blackberry and it should charge..
we prefer not to have users have the software on their pc as most of them don't even know how to turn the blackberries on and off.

i think you need the BB drivers installed at least to get it to charge...