The answer to the question all depends on what type of portable power source that you are using. If it has the option of being plugged directly into a USB port, then you will be able to use it for as long as you need. It’s important to note, however, that some users have noticed that when they are plugged in directly to a power source, some actually lose a little bit of powder and don’t blow as hard.
If you are using something that uses lithium batteries, one charge typically lasts anywhere between 2 and 6 hours before needing to be recharged. Luckily, charging them back up to full usually only takes about 30 minutes). Products that use AA or D cells have a lifespan that is a lot longer than lithium- and last anywhere from 10 to 55 hours. The downside, however, is that when they run out of juice you will have to head to the drugstore to buy more, which means additional cost down the line for the life of the unit.