How Long Does a Car Battery Last With Radio on? – Optimization Tips


Written by

Rafeal Hart


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Norris Howe

how long does a car battery last with radio on

If you have your radio on, your car battery will likely last four to six hours before the battery dies. But suppose you have other accessories running (chargers, lights, GPS, etc.) and an upgraded sound system (speakers, subwoofers, etc.). In that case, your car’s battery may drain in minutes.

So, what happens when you’re playing music in the car with the engine off? How long does a car battery last with the radio on? If the battery is dead, will the radio work? Here are the answers to your questions.

Average Car Battery Life With Radio on


On average, your car’s battery may last four to six hours when you keep your car radio on yet the engine is off. For a more accurate calculation, divide your car’s battery capacity by the radio amperes plus the radio volume.

A car’s battery capacity is usually at 40 Ah, while car radios can range from 0.25 amps to 1.5 amps without amplifiers (old cars) and 1.6+ amps with amplifiers (new cars).

The normal radio volume uses 5 amps of current and could go more than 10 amps when the volume is maximum.

For example, given that you have a 40 Ah battery capacity, 1.6 amp radio power at a conversational volume of 5 amps, you can compute how long you can listen to radio until the battery dies. Here’s how you can calculate the battery discharge rate:

40 ÷ (1.6 + 5) = 6.06 hours of radio-listening time without battery dying

Of course, if you have other car accessories, it may drain your car battery even more. Also, if your car radio has an aftermarket stereo with amplifiers and subwoofers, the radio power could go up to 25 amps, with your radio draining battery even faster.

Factors Affecting a Car Battery’s Life With Radio on


While your car’s battery life will last only for four to eight hours in accessory mode, this still isn’t accurate because of the other factors that can drain your battery even more.

  • External factors

Temperature can affect a car battery’s life. Your car stereo draining battery when off is much faster during winter.

  • Radio type

The time before your car battery dies with car off also depends on your radio type. For example, AM radios use less power compared to FM radios.

Additionally, radio accessories like an amplifier, a speaker, and a subwoofer can decrease the car radio battery.

  • Battery health

Another important factor is your car’s battery health. Older batteries die faster than new ones, whereas new batteries let your radio stay on for about 50% more– without killing battery.

  • Car accessories

If you’re using a lot of car accessories simultaneously without driving, your car’s battery will drain even faster. These accessories include wipers, headlights, etc.

Tips for Maximizing the Battery Lifespan and Making Car Battery Last Longer


Will my car battery die? Practice car battery care to make your battery last for a long time– especially when you plan to use your car radio when the engines are turned off.

  • Keep your batteries clean.
  • Regularly check your battery’s health.
  • Save power when not in use.
  • Properly fasten your batteries at all times.
  • Don’t expose your batteries to the heat.

How Radio Affects Car Battery Life


If your car is in accessory mode and you’re playing the radio, your car’s battery life decreases. That’s because your vehicle uses the battery– instead of the alternator– to run your car’s accessories (including your radio).

The alternator charges your car’s battery and only runs if the engine is on. So, your car’s battery won’t charge since you’re in idle mode. This will eventually kill the battery– especially after a long period.

Determine Car Battery Life With Radio on

Generally speaking, if you leave your car with the radio on for a long period of time, it’ll kill your time. But, how will you know if it’s already harming your batteries?

  • How can I tell if my car battery is about to die?

Your car may have a feature that alerts you if your car’s batteries are about to die. Sometimes, your car radio may automatically shut off when it detects you’re on low battery.

  • How to know if the radio is draining your car’s batteries

We know that playing the radio drain car battery, but how will you know if the radio is the cause of it? To check this, use a multimeter to check how much power your radio is using while on idle.

Tips to Prevent Car Battery Drain While Playing the Radio


Having the radio on with the engine off drains your car’s battery. And no, you cannot disconnect car radio from battery. So, one thing you can do is to not use your car’s radio at all. Instead, bring a portable speaker, pocket radio or a pocket stereo.

Tips for Using Your Radio


However, if you really have to use your car’s radio, you can take note of these tips to use car radio without draining car battery. This will make your car battery last while playing radio.

  • Play your car radio at a lower volume.
  • Turn off all other car accessories while listening to the radio.
  • Have a car audio amplifier.
  • Switch to a solar charger for your batteries.
  • Use an AC/DC converter to save power from listening to the radio.
  • Regularly charge your car batteries.

What Can I Do if My Car Battery Drained

If your car battery drains while you’re listening to the radio, you can start your car with a jump starter. You can also use a jumper cable and connect the battery to another battery.

  1. Have the other car (with working batteries) park beside your car.
  2. Look for the positive (+) terminal of both batteries.
  3. Connect the red clamps to both positive terminals of the batteries. Connect the clamp to the dead battery first.
  4. Start the engine of the working car. Wait for a few minutes.
  5. Start your car.
  6. Remove the clamp from the working car.
  7. Remove the clamp from your car.

Ways to Revive a Dead Car Battery, Recharged Utterly Dead Battery

If your battery goes below 12 volts, your car’s battery is considered utterly dead. But, you can still try any of these methods:

  • Add distilled water and fully submerge the plates.
  • Mix Epsom salt with distilled water if distilled water alone doesn’t work.
  • Use the battery charger or a jump starter.

Frequently Asked Questions


Will the radio function with a dead battery?

Car radios cannot function with a dead battery. A car radio needs power to function. So, if the battery is dead, it won’t be able to turn your radio– and your car– on.

How often should I replace my car battery?

Ideally, you should replace your car’s battery every 4 – 5 years.

However, if you notice that your car takes longer to start, has unusual power fluctuations, frequently needs jump starting, and has dimmed headlights, you may want to consider changing the battery already.

Can I leave my car radio on while the engine is off?

Generally speaking, you can leave your car radio on while the engine is off. But it isn’t the best practice. Leaving the radio on, especially for long periods, drains your car battery. Having a dead battery will only cause more problems to you and your car.


Does having the radio on waste battery? Yes. But how long does a car battery last with radio on depends on many factors. On average, your car’s battery lasts four to six hours when the engine is off.

But if you have an upgraded audio system, many car accessories, an old battery, or are in a cold place, your car’s battery life will be shorter when your radio is turned on for long periods.

Thus, it’s best to maintain proper car battery maintenance to be able to make your car battery last– especially with your radio on.

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