Dear Tom and Ray:
My 16-year-old son drives a 2008 Honda CR-V. He wants to play the car's radio while the engine is off. He wants to sit in the car with the radio on while he is killing time, or while waiting for me while I am in the store. I have told him it's not a good idea, since it could kill the battery.
He doesn't believe me, since his friends supposedly listen to the radios in their cars without the engines running. He says they do it "all the time" -- listening from 10 minutes to half an hour -- and have "never" had a problem with killing the battery. What's your opinion? Can you resolve this standoff?
TOM: Is it his car? If it is, what do you care? If he kills his battery, you can refuse to give him a jump-start until he writes "I will always listen to my sainted mother" 1,000 times.
RAY: Of course, if it's your car he's driving, then I understand why you're concerned. But you really don't need to be.
TOM: The radio uses a very small amount of current -- maybe a couple of amps. That's not enough to kill a battery that's in good condition. Not even close. So, as long as the battery is sound, he can play the radio for an hour or two at a time without doing any harm.
RAY: If your battery IS weak and near the end of its life, then, sure, he might kill it by playing the radio. But in that case, it would have died and stranded you soon anyway. And now you can blame it on him!