WonderTiger:
I did a measurement with a cheap digital volt meter and it came around 2.5V. I think I should invest in a better multimeter in the first place (a buddy of mine has an industrial fluke that works really well he said, maybe I should look for something like that) to get some accurate readings
There are many reasons one might want to upgrade to say a fluke DMM (I own 3) but for the kind of stuff your doing with a typical arduino project a simple cheap DMM (unless defective) will not be a big deal as far as accuracy goes. Like any tool, it's not so much the tool but rather knowing how to use it properly and understanding it's limitations. The biggest draw back of modern DMM is that it always displays a number even when the number being displayed doesn't mean what you might expect it to or want it to mean. Measuring the output of a active PWM pin is one example of a improper measurement for a DMM, it will display a number but it doesn't mean what you think it means.
Lefty