Sorry I should have been more clear. Sometimes if I turn off the truck but leave the key on to play the radio for people who are still inside the truck, and then hop back in and start her up right away and drive off, the gauge won't read full for 15-20 mins. Taking the key out and reinserting it takes care of the wait. And I didnt mean to cause alarm by saying worried, I just meant that if it were taking longer than 10-15 mins, then I would assume something needs to be fixed. Less than that, I wouldn't lose sleep over it. Hope that helps. I would also try what ELVATO recommends.