CMax2013

I got a C-Max Hybrid 2013. Recently, when I turn off the ignition, the radio would play for two minutes exactly and shuts off by itself. I took it to Ford dealer, the mechanic said it was designed that way to save the battery. Is that true? The radio won't consume that much power. I remember having the radio on in a gas vehicle for an hour with no such problem. A few days ago I happened to spot a C-Max Hybrid 2014 in a parking lot, I approached the driver/owner and asked him to turn on the radio with the ignition off, the radio played for over five minutes without shutting off. Just wonder what causes my radio to shut off after two minutes. Maybe the radio was connected to a timer circuit ..... Any suggestions ? 01-20-2015