How Long a Car Battery Lasts with Hazard Lights On?

If you’ve ever had car trouble and got stuck on the road then it’s quite likely that you drew some comfort from engaging and seeing the easily recognizable “signal” for help that comes from the orange blinking of the car hazard lights.

Having hazard lights that work reliably and last for as long as needed is a necessity for your safety and that of others on the road.

They can save you some of the time and effort you’d otherwise spend alerting others about your car situation and help avert accidents by others unaware of the dangers on the road.

So, how long do hazard lights last with a car battery?

knowing how long the lights should last can help you catch an imminent problem with the car’s electrical system – such as if you have a case of parasitic battery drain on the battery or a failing battery that could have taken you by surprise later.

So, read on to learn how long you can expect the car batteries to last with hazards on, why they may not be lasting as expected, and for suggestions on how to get them to last longer.

Do Hazards Lights Drain the Battery?

Yes, car hazard lights can drain the battery flat and possibly kill it too. Hazard lights draw approximately 4 amps (2 pcs x 2 amps) from the battery every time they flash. Note: assumes 24-watt signal light bulb.

Even though these lights don’t light continuously and flash on and off, over time the power consumption adds up and can deplete the battery charge.

Can they Kill the Car battery?

Yes, hazard lights can contribute to the failure of a car battery. Repeated deep discharges of the battery, more especially aging batteries accelerate their failure.

Car hazards have no auto-shutoff feature and unless switched off manually continue to draw down the battery charge until it is drained flat.

Can Hazards Drain a Car Battery in under an Hour?

Yes, it is possible for hazard lights to drain a car battery flat in under an hour if the battery is partially charged, damaged, aged and unable to hold charge.

If the battery is fully charged and in good condition, they run for longer. If the car battery is in good condition and fully charged yet draining in under an hour, it is likely that there other accessories or a fault causing of parasitic drain.

You may also be interested in 6 Reasons why your car battery may be draining

Related Questions

Can Hazard Lights Work when the Car Battery is Dead?

No. The hazard lights draw power from the battery to light. If the battery has no charge then the hazard lights will not work unless you are using battery-powered strobe lights.

How Long a Car Battery Lasts with Hazards On?

This depends on many variables, but as a rough guide, the car hazard lights can last for about 12 hours before they drain a 55 Ah car battery to 50 % of its capacity. This estimate assumes a fully charged, 55 Ah battery still in good condition (able to hold charge) and that each of the two hazard light indicator bulbs is rated 24 watts.

How Long Hazard Lights last with the ignition On?

If the ignition is switched on, the hazards will last an even shorter time because of the additional power draw of the ignition circuit.

Note: Car hazard lights can still work even when the ignition is off.

You may also be interested in How long a car battery lasts with the headlights on

How Many amps Hazard Lights Draw?

Two hazard lights each with a 24-watt bulb draw between 2 amps every second when lighting. The actual current draw depends on the actual wattage of the bulbs.

If the ignition is still switched on, the current draw can be higher.

The math

The current draw can be obtained from the formula: current (amps) = (combined power consumption of the headlamps)/car battery voltage

(2 x 24 watts)/12 volts = 4 amps

Why your battery may not be lasting as long with the hazards on?

If the car battery is not lasting as expected, check:

#1. That the battery is not partially charged. If the car is only driven over short distances occasionally, it is likely that the battery is not charged and will therefore not last as long as expected with the hazards on.

#2. Are there any other accessories on? It is possible as well that in addition to the hazards being on, there are other accessories that may be switched on – interior dome light, and headlights that add up to the overall power consumption on the car.

So, confirm that it is only the hazards otherwise your concerns of the battery not lasting may not be accurate because it is the hazards plus other electronics draining the battery.

#3. The car battery may be on its way out. An aging battery is not able to hold charge as well as a new battery even when fully charged.

How old is your car battery? While there is no consistent information on how long a car battery can last, there is a high likelihood that you’ll need to replace your car battery at about the 3-year mark.

Tips to Get the Car Battery to Last Longer with Hazards

#1. Replace your incandescent flasher bulbs with LED bulbs. They generally draw less power while still giving off enough light and can extend how long the car battery lasts with the hazards on.

#2. Purchase a battery tender to connect and top up the car’s battery when parked for extended periods. Onboard sensors and computers can drain the car battery power over time.

This coupled with only taking the car out for short drives will likely result in the car battery lasting a short time with the hazards on.

Final Word

If the car battery is fully charged and in good condition, the 2 x 24 watts car hazard lights bulbs can last for about 12 hours before they drain the car battery to 50 % of its capacity.

Actual runtime depends on battery capacity, age, ability of the battery to hold charge, and whether there are other accessories that are still drawing power from the battery.

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