Should You Disconnect Your Car Battery When Changing A Headlight?

You suddenly realize that your headlight is out and needs to be replaced. Do you need to disconnect the battery to change the headlight?

Do I need to disconnect my cars battery when changing a headlight 1 Should You Disconnect Your Car Battery When Changing A Headlight?

Do I need to disconnect my car’s battery when changing a headlight?

It is a good idea to disconnect the battery when changing a headlight since the light assembly is connected to your vehicle’s electrical system. While it is not likely that you will touch a live wire, it is possible. The safest approach is to disconnect the ground wire of the battery.

Many car owners wonder about their vehicle’s electrical system and are scared to touch anything for fear of damaging the circuits. 

While most car batteries have enough amperage to do severe damage to you, the voltage of 12V is not enough to cause any harm. However, many new hybrids and EVs have more extensive batteries with batteries that have much higher voltages and will cause extensive injury or death. 

Why Should I Disconnect the Battery When Changing a Headlight?

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On standard vehicles, the battery is the power source for your automobile. 

While these batteries do not have enough voltage to cause issues, static electricity or a connecting piece of metal that connects between the positive terminal and negative terminal post could provide a shock. 

As any mechanic will tell you, they never work on a car with jewelry (rings, etc.) because it can create serious issues, like potentially shorting out the battery. 

Headlights use wiring and connector sockets to hold bulbs in place. 

On some models, you can twist the bulb out of the headlight assembly, insert a new bulb and reinstall. On other models, you have to replace the whole headlight assembly (it is removed by loosening the screws under the hood and unplugging the wiring pigtail). 

Inside the wiring, the socket has a live connection to the battery, which could provide a bit of a shock if touched. (It’s not likely, but it is possible). 

Electric vehicles and Hybrids are entirely different beasts. They contain high-energy batteries that often run 200 – 800 volts, making them very dangerous. 

More and more first responders are being instructed on handling the risk of electrocution when responding to an accident involving an EV or hybrid. 

Manufacturers are working hard to mark high-voltage lines to help technicians and owners know what not to touch. 

The experience of working on an electric vehicle powered by lithium-ion batteries is still a relatively new development, and dealerships are scrambling to find trained technicians to fill the growing needs of EV owners. 

The bottom line is that if your headlight bulb goes out on your new EV, it is always best to have a certified technician replace it, so you don’t accidentally create an issue that you can’t handle (like a fire or death). 

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Should I Disconnect the Battery on my EV if going on Vacation?

Your electric vehicle’s manufacturer can advise you on what you should do. In some cases, it is acceptable to keep your vehicle plugged in during your vacation period. 

If you are planning on being away from your vehicle for longer than a month, disconnect the negative cable to the 12 V battery.

What Does Replacing a Headlight Cost?

The amount you will pay to replace a headlight bulb will vary depending on the vehicle model and the type of bulb used. 


Halogen bulbs are the cheapest to produce and are also the easiest to replace. These bulbs are inexpensive to purchase (although the dealership will want to charge you labor for installing them). You should pay twenty dollars for a halogen light bulb. 


Xenon or HID (High-Intensity Discharge) lights are more expensive, costing upwards of a hundred dollars or more.

They last longer than halogen bulbs and should be replaced every three years. The disadvantage of xenon is that, over time, they begin to lose its effectiveness.

LED lights 

These smaller lights are used in a series and are made of tiny bulbs in a symmetrical pattern. If one of a hundred tiny bulbs fails, it is not as big as when a whole halogen light stops working. 

The drawback is that enter must be replaced to correct lighting problems. 

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Should I Replace Both Sides if One Headlight is out?

Yes, changing out both sets of lights is best whenever one goes bad. The way vehicles are designed today, it is a safe assumption that when one goes, the other is sure to follow. 

Many owners wait until the other headlight stops working, but this just requires a second trip to the service center.

Given that headlight bulbs deteriorate over time, becoming less bright, I can’t think of a legitimate reason not to replace both headlights to get the maximum benefit of illumination possible. 

What happens if I Replace the Bulb, but the Headlight isn’t Working Again?

A frequently blowing bulb means a severe issue with your vehicle. 

There could be wiring issues (nasty pigtails or loose wiring), a cracked socket that shorts out the connection, or too much load being sent through the circuit. 

The best way to search for the culprit is to examine the sockets for any sign of black melted plastic. 

That is a clear indication that things are not right. (It is possible that the technician who replaced the last bulb broke the connector or socket trying to replace the bulb. 

There are times when a manufacturer makes a mistake. 

Either they didn’t design the headlight harness to carry the load correctly, or it wasn’t appropriately assembled when it was at the plant. 

Either way, it can be very frustrating to have to continue to replace headlights multiple times, and since headlight bulbs are not covered under warranty, the money can add up in a hurry. 

Key Takeaways

  • It is always a safe idea to disconnect the battery whenever you work on your car.
  • Current standard car batteries do not have enough voltage to harm a human.
  • EV batteries are hazardous and should be avoided by all but trained technicians.
  • A Headlight that keeps going out is a sign something else is wrong with the wiring.
  • Only Certified Technicians should work around high-voltage EV batteries.

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