What happens if a Highlander Hybrid battery dies?

If the battery in a Toyota Highlander Hybrid vehicle dies, it can cause significant issues with the vehicle's operation and performance. The Highlander Hybrid relies on a complex hybrid system that integrates an internal combustion engine with an electric motor and battery pack, and a failure in the battery can disrupt this delicate balance.

Understanding the Highlander Hybrid Battery

The Toyota Highlander Hybrid is equipped with a high-voltage battery pack, typically a nickel-metal hydride (NiMH) or lithium-ion (Li-ion) battery, that stores the electrical energy used to power the electric motor. This battery works in conjunction with the gasoline engine to provide a seamless and efficient driving experience. The battery is a crucial component of the hybrid system, as it allows the vehicle to operate in electric-only mode for short distances and provides additional power during acceleration.

What Happens When the Battery Dies?

When the Highlander Hybrid battery dies, the vehicle will no longer be able to operate in its intended hybrid mode. The gasoline engine will still function, but the vehicle will lose the benefits of the electric motor and battery, such as improved fuel efficiency, reduced emissions, and enhanced acceleration. The vehicle may also experience the following issues:

• Reduced power and performance: Without the assistance of the electric motor, the vehicle will rely solely on the gasoline engine, which may not provide the same level of power and acceleration.


• Decreased fuel efficiency: The Highlander Hybrid's fuel efficiency is largely dependent on the hybrid system's ability to switch between the gasoline engine and electric motor. With a dead battery, the vehicle will not be able to take advantage of the electric motor, resulting in lower fuel economy.


• Warning lights and error messages: The vehicle's onboard computer may display warning lights or error messages related to the hybrid system, indicating that the battery is no longer functioning properly.


• Potential safety issues: In some cases, a dead battery can cause the vehicle's safety systems, such as the airbags or brakes, to malfunction, posing a risk to the driver and passengers.

It's important to note that the Highlander Hybrid is designed to provide a certain level of redundancy, allowing the vehicle to continue operating in a limited capacity even with a dead battery. However, it is recommended to have the battery replaced as soon as possible to restore the vehicle's full hybrid functionality and performance.

Replacing the Highlander Hybrid Battery

Replacing the Highlander Hybrid battery can be a complex and expensive process, as the battery pack is a specialized and integrated component of the vehicle's hybrid system. The cost of a replacement battery can range from $2,000 to $4,000 or more, depending on the specific model year and battery type. It's essential to have the battery replaced by a qualified Toyota dealer or authorized service center to ensure the proper integration and calibration of the hybrid system.

In summary, a dead battery in a Toyota Highlander Hybrid can have significant consequences, affecting the vehicle's performance, fuel efficiency, and even safety. Prompt replacement of the battery is crucial to restore the hybrid system's functionality and maintain the vehicle's overall performance and reliability.

What happens when a Toyota hybrid battery dies?

When a Toyota hybrid battery dies completely, the car typically becomes inoperable because the hybrid battery is essential for starting the gasoline engine. The engine relies on the electric motor, powered by the high-voltage battery, to crank the engine, a function the traditional 121212V battery cannot perform. This means the car will not start, and even with a full tank of gas, it will not run.
 
This video explains what happens when a hybrid battery fails: 1mThe Car Care NutYouTube · Jan 11, 2025
Immediate effects

• Inoperable vehicle: The car will not start, as the high-voltage battery is the primary starter for the gasoline engine. 
• Limp mode and no power: Some models may enter a temporary "limp mode," but a completely dead battery will render the car immobile. 

What happens to the car's systems

• No start-up: The car will not be able to turn on or move, even if the 121212V battery is fine, because the 121212V battery is only used to engage the relays that connect the high-voltage battery. 
• Engine and transmission: The hybrid battery is not only for propulsion but also for starting the engine and creating reverse gear, so its failure will disable both functions. 
• Warning lights: A dying battery may trigger various warning lights, such as the red triangle, the check engine light, and the vehicle stability control (VSC) light. 

What to do

• Diagnosis: Have the hybrid system diagnosed to confirm the battery is the issue. 
• Replacement: The high-voltage battery will need to be replaced to make the car drivable again. 
• Professional help: A professional is needed to handle the high-voltage system, as it contains high voltage that can be dangerous. 

Can you drive a hybrid car with a dead hybrid battery?

No, you cannot drive a hybrid car with a dead hybrid battery; it will not start or run. In most modern hybrids, the hybrid battery system is essential for starting the gasoline engine and powering the transmission, meaning a complete failure of the battery will immobilize the vehicle. 
This video explains why you can't drive a hybrid with a dead battery: 32sHumble AcresYouTube · Feb 22, 2020
Why a hybrid won't start with a dead battery

• No engine start: Many hybrids lack a traditional starter motor. Instead, they use a motor-generator powered by the high-voltage hybrid battery to start the gasoline engine. If the battery is dead, there is no power to crank the engine. 
• No transmission power: The hybrid system controls the power flow to the transmission, and if the battery fails, the transmission cannot receive the necessary power to function. 
• Electronic control: Even if the gasoline engine is fine, the hybrid system requires electrical assistance from the battery to operate correctly, so the car becomes inoperable. 

What you can still drive

• 12V battery is still functional: A hybrid car has two batteries: the high-voltage hybrid battery and a smaller, 12-volt battery. If only the 12-volt battery is dead, the car can still be driven once it is jumped, and you will have power to run the electronics and start the engine. However, if the high-voltage hybrid battery is the problem, the car will not run. 

This video explains the symptoms of a failing hybrid battery: 1mThe Car Care NutYouTube · Jan 11, 2025
What to do if your hybrid battery is dead

• Do not try to drive it: A dead hybrid battery will prevent the car from starting. Attempting to drive it will not work and is not recommended. 
• Get it towed: Have the vehicle towed to a mechanic or a hybrid specialist for diagnosis and repair. 
• Replace the battery: The hybrid battery will need to be repaired or replaced to get the car running again. 

How to start a Toyota Highlander with a dead battery?

And that is how you get in your vehicle. And get it started if your key fob battery has died i hope this video was helpful feel free to comment with any questions you may have thanks for watching.

How much does it cost to replace the hybrid battery in a Toyota Highlander?

It can cost anywhere from $1,999 to $3,299 to replace a Toyota Highlander Hybrid battery, based on the year and model of the battery. At Greentec Auto, you can get a remanufactured Highlander hybrid battery for as low as $1,999 with an 18-month warranty, or new cells for $3,299 with a 36-month warranty.