Totally normal. Cordless angle grinder are some of the most demanding & consuming tools regarding batteries/ battery life.
Since Festool will have 4 Ah "high power" (21700 cells) compact batteries for sale beginning in January (for Germany/Europe), I'd honestly wait and see if they also upgrade the current, bigger 6.2 Ah Airstream batteries.
That said, your tool & overall work will definitely profit from 6.2 Ah airstream batteries & airstream charger: Less charging time, air cooled while charging.
But if you can, wait a little and see if there will be some upgrade and get the new batter(y)ies and charger then.
(Then again, theres nothing wrong in having also some of the current 6.2 Ah airstream batteries and charger. (Will work with your PDC & BHC, too.)
![Big Grin [big grin]](https://www.festoolownersgroup.com/Smileys/default/biggrin.gif)
)
Kind regards,
Oliver