If doing this do make sure your bottle is within it's certification time. You do not want one exploding on you - it would probably be fatal if you were near it. I suggest being somewhere else whilst the charge is in progress. You might also want to add an air drier.
Shocked you don't have a real air dryer on it. I send mine through two and I drain off water after every fill in the dryer. Without one, you are definitely getting moisture.
I got one of those. The tank connector tube blew at 2500 psi after 10 minutes of use. Fixing that one it took another 30 seconds to blow the second stage head. Complete crap