How Long Can Hazard Lights Stay On Before Battery Dies?

We often ignore how much battery hazard lights or emergency lights consume. However, if the car engine isn’t working and you need to switch on the hazard lights, you might be concerned about how much battery they’ll drain. So, how long can hazard lights stay on before battery dies?

It is always good to know what you have in store beforehand to avoid uncertainties. Moreover, hazard lights prove to be a savior when your vehicle might be a potential risk for other vehicles on the road. We’ll tell you about hazard lights and their battery consumption level in detail in this post.

Do Hazard Lights Consume Battery?

Yes, hazard lights drain battery. If you leave the hazard lights on for too long, they can drain the power completely. However, the hazard lights are designed to use minimal energy to reduce the drain on the battery. However, if you ignore the battery consumption of the hazard lights, it will kill the battery. If the battery is completely dead, the car won’t start.

Do Hazard Lights Consume Battery

How to Calculate Hazard Lights Battery Usage?

To explain this, we need to understand the rate of power consumption of the hazard lights. The car batteries have ratings in Amp-hour or Ah. This unit indicates the amount of electricity the battery can deliver over a period.

In general cases, your car batteries have a higher rated power. The ideal capacity of a car battery is around 80 Ah for group 24 oversized vehicles. The hazard lights or signal lamps take about 2 Amps to run. If you turn on all the four hazard/emergency lights on your car, it will draw around 8 Amps per hour (if they remain on all the time). However, since they stay on half the time, we can assume that the lights draw around 5 Amps from the battery hourly.

We can now divide the total power consumption of the vehicle’s hazard lights from the total power capacity of the battery. Dividing 80 (Ah) by the consumption 4 (A) gives us 20 hours. If we divide 80 (Ah) by 5 (A), we’ll get 16 hours of runtime.

We have calculated the runtime according to the standard power consumption rates of the hazard lights and the power capacity of the vehicle’s battery. To calculate the exact runtime, you must check the power rating on your vehicle’s battery and the hazard lights. Recalculate the whole thing according to the available rating; you’ll get the exact runtime.

How Long Can We Leave Hazard Lights on Before Battery Dies?

You can leave the hazard lights on for sixteen to twenty hours before the battery dies completely. To be on the safe side, we recommend leaving the hazard lights on for around four to five hours to be on the safe side before the battery gets weak.

How Long Can We Leave Hazard Lights on Before Battery Dies

Different car batteries have different specifications, and their draining time varies. The ratings for Amp-hour are different for batteries, and how much a vehicle uses the battery is also different. There might be other electronic components such as headlights that may draw energy from batteries.

The current vehicles consist of LED hazard lights or warning lights, and they can operate for several hours without draining the battery completely. However, if the car is old or you haven’t charged the battery fully, the time for hazard lights will decrease.

Do Hazard Lights Automatically Switch On/Off?

Numerous vehicles have hazard lights that switch on automatically in some situations. For instance, if you press the brakes too hard or when the vehicle’s system detects that the driver has pressed the brake more than the threshold limit.

Do hazard lights automatically switch on off

If you see that your hazard lights are switching on without any reason, the switch circuit is grounding. The fault can either be in the wiring or the switch. Sometimes, it can also occur because of a failure in the combination flasher. If you have fixed the issue and the hazard lights are still flashing, unplug the lights and check a short circuit.

When to Use Hazard Lights?

Hazard lights aren’t just for aesthetic purposes in a vehicle. According to the actual definition of hazard lights, these are driver-controlled devices that cause the light to flash immediately so that the approaching drivers know that there is a vehicle. In some states, some laws determine when a driver can use the hazard lights. Following are some situations where you can use hazard lights:

When to Use Hazard Lights

  • Your Car Breaks Down: If you’re having trouble with your car, move it to a safe position and turn on the hazard lights.
  • You’re Asked to Stop by a Police Officer: In such a situation, turning on the hazard lights indicates that you’ve understood the police officer’s direction and will pull over as soon as possible.
  • Changing a Tire: If you have to change your vehicle’s tire on the road, turn on the hazard lights so that other drivers are aware of it. This is important if the weather is rainy, foggy, or dark around.
  • Medical emergency: Turning on hazard lights is helpful in emergencies, especially if you have an ill or injured person in the car. This way, other drivers know that you need to reach a spot immediately, and they reduce their vehicle speed to let you go.

Tips to Keep Your Vehicle’s Battery Healthy

If you’re using the electronics on your vehicle while driving, the alternator provides the power for running. However, things start getting troublesome when the load comes to the vehicle’s battery. Therefore, you should not keep the hazard lights switched on for hours when your vehicle’s engine is off.

Apart from the battery draining issue, this can also cause corrosion issues. This action also causes the plates to sulfate. Thus, the ability of the battery to receive the charge also decreases.

To keep your car’s battery healthy after using the hazard lights, connect it to a battery charger. The use of a dedicated battery charger breaks down the sulfate crystals on the lead plate before they become hard to remove.


Hazard lights can drain the battery, especially if you switch them on for long. However, now you have all the information, you won’t let your battery die while you’re using the hazard lights. Additionally, we advise you to try marine deep cycle batteries or golf cart batteries to help your battery last longer as they provide a longer battery cycle.

Whatever the situation is, never leave the hazard lights on and unattended for an extended period. It would be best not to keep any electronics on your vehicle turned on while the engine is off.