Keep radio on at drive-in theater

[bamorris2]

For those of you that go to drive in theaters in your truck, how are you keeping the radio on through the movie? Mine times out after 10 minutes or so. I know there’s a service mode, but worried that could drain the battery faster. Any other way to keep the radio on?

[blckblt]

Our drive in has large outdoor speakers so it hasn’t been a problem here. 
 

if they didn’t have speakers I was going to get one of the ryobi cordless (battery powered) radios. Pretty much all cordless power tool brands make a radio (some double as a compressor). 
 

we usually back the truck into the spot and sit in the bed or lay with an air mattress so listening to the truck radio would have difficult. 

[c.schill]

If you frequent drive-in theaters like I do, something like this is the best thing you can get. I have one that I got for $179 on sale at Sam's Club, and it's one of my favorite things I own. It makes drive in movies so much better, audio wise.

[Smart RVing]

The simplest way to keep radio on at drive in. Step 1. Put your car in accessory mode. Step 2. Connect your radio to the drive-in’s sound system. Step 3. Connect the battery pack.

[GN2018]

Haven’t been to a drive in movie in a looooong time.  But, I was wondering, would leaving the truck in service mode so that the radio stays on really drain the battery?  I know it could be on for 2-3 hours, but would a battery that’s in good shape get drawn down enough to matter?