Will listening to the radio in the car, ignition off, parked, drain the car battery too much?


Roughly speaking, how many hours can one sit in the car doing nothing but listen to the radio without draining the battery too much so that the car will start when you need it to?

Is this a matter of hours? Days? generally speaking.


If your battery is fully-charged and in good condition, I believe that you could probably listen to the radio all day w/o impairing the ability to start the engine. Modern solid-state radios drain very little power.

Edited to add:
However, if you are one of those folks who has installed a powerful amplifier, and who likes to listen to the audio system at ear-splitting volume, a couple of hours of “listening” could drain the battery to a considerable extent.


If you have a large display screen (i.e, navigation) that remains on, you’ll drain the battery a lot faster. Be sure to turn that screen off if you’re going to be listening for a long time.



Here’s my advice

Have your battery and charging system thoroughly checked out. Make sure the guy also checks for parasitic draw.

If everything checks out, I don’t see a problem listening to the radio for, say, 5 minutes with the engine off.

By the way, how old is that battery?

If it’s more than 5 years old, it might be just about time for a new one.

I recommend Costco, if you’re a member and need a battery.


In general agreement. A healthy battery, a radio only with no aux powered speakers, normal volume and no problem. Now, if you intend using it to party for hours at high volume on the beach, get a couple of jumper batteries, to be safe. But, for low volumes, get a self powered rechargeable speaker for your IPod.


Our drive in has audio over am radio, double feature, four hours or so seems fine for most cars. Unfortunately films are a thing of the past, and now the drive in will be due to the cost of upgrading to digital.


As @VDCdriver said, a lot depends on the ‘radio’. Aftermarket? Big amp? LCD? Or just a stock unit with low power output? @mareakin - let us know.


Agree; a standard radio drains very little current. However, if you install a killer aftermarket system as my son did, you can not only drain the battery quicly but also blow the alternator. My son had to upgrade the whole system, even though the car came with a trailer towing package which includes a heavier alternator and battery…


like others have clearly said…it depends.
no one answer fits all.
one’s battery health is something rarely wondered about …till it’s too late.

one evening after work we were making multiple stops to get dinners on the way home. Each one wanted something different so we stopped at three different places and each time the daughter played the radio while waiting.

I thought nothing of it.

Third stop , McDonalds.
Came out with the loot and hopped in the truck…radio still playing normaly…tktktktktktkktktk ! !

now, here’s a major design flaw in the 08 Expedition, the rear gate and window are electric ONLY !!!
That’s where my tools are !
so here I go climbing over two rows of seats to get to my cables.

getting a jump turned out to be effortless. this is a nice small town town and most are quite neighborly. I was not yet done pushing the truck back to gain access to the hood and already had an offer to jump.

But I was quite surprised by the lack of battery reserve.




The car is a 2007 Corolla CE with the cheap stock radio, no screen or anything like that. The battery is a Costco Group 35, about 3.5 years old. In addition to the radio, I will be using an FM transmitter (so I can listen to the music on my phone via BlueTooth) and probably I’ll use a Laptop too. The laptop will be powered using one of those power inverter things.

The laptop charger can provide up to 65W, that’s a maximum so I doubt it’s operating at that most of the time. The FM transmitter draws a negligible amount of power, I think.

I remember the old days when portable boom boxes ran on several D batteries, my guess is that the drain is very slight. The biggest power draw will probably be that laptop.


If I were doing this regularly, I would use an external, rechargeable power supply and I would not be worrying. As a rule, I confine my car battery to temporary use only with the ignition off.


I have a customer with a 2011 Infiniti. I recently did the 60,000 mile service. Found a weak battery and replaced it. A week earlier he was waiting for his wife listening to the radio for 20 minutes and had to call for a jump start. I’d expect any battery over 3-4 years old to have a reserve capacity of an hour or two with the key on, maybe.

@"ken green"‌ “But I was quite surprised by the lack of battery reserve.” Your battery is 6 years old. It’s at the end of it’s life, you need a new one.



Here are a bunch (sample)of jump batteries, which are great to have in general, that are expressly made for your needs. If you already have an inverter, cheaper ones work. I have a couple, one I have had for 9 years that I use camping, jump starting and even as a one hour emergency trolling motor. It has yet to fail holding a charge.


The lack of good reserve surprized me because the battery was new in october 09 in the used truck prep.
And the incident happened sometime early '13.
a three year + Motorcraft BXT650 battery.


Back in the day, when there were still a few drive-in movie theaters open, but after they stopped using the clip-on speakers, they used to say that listening to the radio for the length of a movie uses less battery juice than starting the car once. If you have a healthy battery, that is usually true; you can listen to the radio for two or three hours without running the car battery down, and when you’re done, you should be able to start the car.

EDIT: The power inverter you intend to use is a very inefficient device, and it is probably most likely to drain your battery. If you have the option, I recommend you run the laptop computer and the FM transmitter on their own batteries. The radio itself probably won’t run down your car battery, but additional accessories probably will.

Your laptop computer comes with its own battery. Why would you want to run it on an inverter with the car off? Charge it on the way there and on the way home, but use the laptop computer’s battery while you’re there. If you know how to use them, you can change the computer’s power settings so the battery will last longer.


My parents would tell the story of my father running down the battery with the radio on one of their first dates.
This was right after WWII and the radio had vacuum tubes.
My mother thinks he let it happen on purpose.


I’d be a little careful myself. I realize the new radios don’t take the power like the old tube types, but I’d have a back up. As a teenager I borrowed my dad’s 1960 Falcon to tool around in Friday night. He warned me not to use the radio but I didn’t listen. Sure enough after a couple hours of driving around and using the radio too, the battery was dead when I tried to start it again. I never told him, but shut the radio off after that.


@Bing: While the newer radios may not waste as much as tube radios did with having to provide filament current and boost the 12V supply for plate voltage, the tube radios didn’t have 300+ watt amplifiers like most modern cars do either, to say nothing of DVD players, multiple monitors, WiFi and Bluetooth transceivers, etc. Your dad’s car may have had a weak battery too, and a lot of cars in that era still had generators that didn’t provide a lot of charging current, especially at low speeds. Maybe a maximum of 30 amps. It’s hard to believe that a 1960 car wouldn’t have a transistor radio though. Someone more familiar with Fords of this era can correct me.

Some cars are pretty resistant to running the battery down this way–think luxury cars that have V8s and big batteries for starting and running all the myriad accessories. Then there are others–the Honda Fit comes to mind. I remember at least two posts to this forum by Fit owners that ran their batteries down by just listening to the radio for under a half hour, probably at fairly low volume. I’m sure the dinky electrical capacity is from a combination of not much space for a battery, weight savings for fuel economy, and not as many accessories to run, so not as much reserve capacity was specified for the stock battery requirements.


Whether you’re playing a CD, a cassette tape, or an eight track tape, anything with moving parts will use more electricity than solid state options like the radio or an MP3 player. In this particular case, we’re talking about playing music from a laptop computer, so as long as that laptop computer and FM transmitter are running on their own batteries, the OP’s battery should be able to handle it.