Device well - battery power bad

We have the equipment now used at 5 years, and two kids. The performance is very good, music remotely controlled, two-way communication, etc.
But the gravierenste disadvantage the poor battery runtime of the parent.
Mostly after 2 hours the batteries (battery) AAA are already leergelutscht.
And there is absolutely no reason to because the design would allow loose the larger AA, the there are now battery with up to 2500 mA / h.
Just not thought through