Car engine noise happens when the battery is full on 2008 Toyota Prius

Car engine noise happens when the battery is full, especially when going down the slopes and the battery charge full...

coming down when i Stomps on the accelerator
whats the problem ??

2 answers
Nobody knows! A Toyota tech 'might' if he test drove it then ran a diagnostic test. Oh you'll probably get plenty of gusses! Hang in there!!

Here you go!!
Are you using "B" mode when going downhill?