I did a Search but could not see this topic so .....
I make no apolgies. I've copied this from another forum in case anyone on here is not aware of how to increase the radio cut off time with ignition off beyond 20 minutes ....... it worked for me ...
Arthur

"If a customer wishes to change the amount of time the radio will stay on, please
follow the instructions below:

* Turn radio on using central ?power? button
* Within 15 seconds, simultaneously press ?FM AS? and preset button ?2?. Each
time this pair of buttons are pressed, the display will alternate between
?NORMAL POWER MODE? and ?CAMPER POWER MODE?
* Ensure that ?CAMPER POWER MODE? is displayed, then press ?MENU?
* Using the ?UP? and ?DOWN? button now changes the display to show various
adjustable items. Cycle through the options until ?RADIO OFF? and a number of
minutes is shown on the display. This will take approx. two presses of the ?UP?
button or seven presses of the ?DOWN? button.
* With ?RADIO OFF? shown on the display press the ?LEFT? or ?RIGHT? button. Each
press of either button will alternate the number of minutes shown between ?180?
and ?0?
* With ?180? showing on the display the setting is complete and three hours of
radio operation should be possible. Press the ?POWER? button to exit the menu
and return the display to its usual view.

Please note that in ?NORMAL POWER MODE? the same subsequent steps detailed above
can be followed, to choose between ?20 mins? and ?0 mins? of radio operation. "