Yes, you can charge a battery electric vehicle (BEV) while its engine is off, and in some cases, even while it’s running, depending on the vehicle’s design and the charging method. However, the idea of charging an electric car while the engine runs is a misunderstanding for most modern EVs. Let’s dive deep into the nuances of car charging while running, idling and charging EV, and how EVs manage their power.
The world of electric vehicles (EVs) is constantly evolving, and with it come many questions about how these innovative machines operate. One common query that arises is whether it’s possible to charge an EV while the vehicle is in operation. This encompasses various scenarios, from charging electric vehicle stationary with the engine off, to the more complex concept of using car engine to charge battery or charging while driving. This article aims to demystify these questions, providing a comprehensive look at EV charging practices and the underlying technology that makes it all possible, focusing on maintaining battery charge while on and whether you can I keep my car running while charging.
Image Source: co-charger.com
Deciphering EV Charging Basics
Before we tackle the “while it’s on” question, it’s crucial to understand how EVs are typically charged. EVs rely on electricity stored in a large battery pack. This power is replenished through a connection to an external power source.
Stationary Charging: The Standard Approach
The vast majority of EV charging occurs when the vehicle is stationary. This is the most common and safest way to charge.
- Level 1 Charging: This uses a standard household outlet (120V in North America) and is the slowest method. It’s akin to charging a smartphone overnight. You plug the EV into the wall, and it charges. The vehicle’s engine, of course, is off. This is the most basic form of engine off charging electric car.
- Level 2 Charging: This utilizes a dedicated 240V charging station, often installed at homes or public charging locations. It offers significantly faster charging speeds than Level 1. Again, the vehicle is stationary, and the engine is off.
- DC Fast Charging (Level 3): These are high-powered charging stations found at public charging hubs. They deliver direct current (DC) power directly to the battery, allowing for very rapid charging. The vehicle is always stationary for this, and the engine is off.
In all these standard charging scenarios, the vehicle is parked, and its propulsion system (if it even has an internal combustion engine in the case of plug-in hybrids) is not actively being used for driving or significant power generation.
The Nuance: What About Charging While Running?
Now, let’s address the core of the question: Can I charge my car while it’s on? This can be interpreted in a few ways, and the answers vary.
Scenario 1: Charging a BEV While “On” (But Not Necessarily Driving)
If “on” simply means the vehicle’s electrical systems are active, then yes, you can technically charge a BEV while it’s in accessory mode or “on” without driving. The battery management system (BMS) and the charging system are designed to manage power flow. However, there’s no practical benefit to charging a BEV while it’s stationary and simply “on” with its engine off, as this is the same as charging electric vehicle stationary.
Scenario 2: Idling and Charging EV (For Plug-in Hybrids – PHEVs)
This is where things get a bit more complex and often lead to confusion. For plug-in hybrid electric vehicles (PHEVs), they possess both an internal combustion engine (ICE) and an electric motor with a battery.
- Can a PHEV charge its battery while idling? In most PHEVs, the ICE is primarily designed to drive the wheels or provide propulsion. While the engine is running, it can generate some electricity, but this is typically used to power the vehicle’s systems directly or to trickle-charge the battery, not to perform a rapid or full charge. The primary charging method for a PHEV is still plugging it into an external power source.
- Is it efficient to charge a PHEV while idling? Generally, no. Running an ICE consumes fuel. While it might contribute a small amount of charge, the energy expended by the engine is usually far greater than the energy gained by the battery through this method. It’s far more efficient to use external charging methods for PHEVs. The concept of using car engine to charge battery in a PHEV while idling is not an efficient or primary charging strategy.
Scenario 3: Running Engine Charging Electric Car (Range Extenders/Series Hybrids)
Some vehicles, often referred to as “range extenders” or series hybrids, are designed with a small gasoline engine that acts purely as a generator to charge the battery.
- How it works: In these vehicles, the gasoline engine doesn’t directly drive the wheels. Instead, it runs at an optimal speed to generate electricity, which then charges the battery or powers the electric motor. So, in a sense, you are charging electric car while engine runs or running engine charging electric car. However, it’s important to note that this is a built-in system, not an aftermarket modification or a standard EV behavior. The vehicle’s management system is optimized for this.
- Example: The BMW i3 with its optional range extender is a classic example. The small gasoline engine would run to charge the battery, extending the vehicle’s range.
Scenario 4: Charging While Driving (Regenerative Braking)
This is a very common and effective way EVs (and hybrids) recapture energy, but it’s not “charging” in the traditional sense of plugging in.
- Regenerative Braking: When an EV driver lifts their foot off the accelerator or applies the brakes, the electric motor reverses its function, acting as a generator. This converts the vehicle’s kinetic energy (motion) back into electrical energy, which is then stored in the battery. This is a form of charging while driving, but it’s always happening passively as a byproduct of deceleration. You’re not actively plugged into a charger while doing this.
The Big Question: Can I Keep My Car Running While Charging?
Let’s directly address: Can I keep my car running while charging?
- For Battery Electric Vehicles (BEVs): This question usually arises from a misunderstanding of how BEVs work. BEVs have no internal combustion engine to “run.” They are powered solely by electricity from the grid or other charging sources. So, the concept of charging electric vehicle stationary while the engine runs is not applicable to pure BEVs. The vehicle is “on” in terms of its electrical systems, but there’s no engine to keep running.
- For Plug-in Hybrid Electric Vehicles (PHEVs): If by “running” you mean the gasoline engine is on, then yes, a PHEV can be plugged in and charging while the engine is also running. However, as discussed, this is generally not recommended as it’s inefficient. The car’s computer will likely prioritize battery charging via the external source, but the idling engine is still consuming fuel. The optimal way to charge a PHEV is with the engine off charging electric car systems via the plug.
Why You Shouldn’t Typically Charge a BEV While Driving
While regenerative braking is a form of charging while driving, the idea of plugging a BEV into a charger and driving it simultaneously is not a practical or intended use case.
- Physical Limitations: Charging cables are designed for stationary use. Driving while plugged in would create immense strain on the cable, the charging port, and potentially the charging infrastructure, posing safety risks.
- Power Draw vs. Charging Speed: Even if it were physically possible and safe, the energy consumed by driving would likely far exceed the energy being supplied by even a fast charger. You wouldn’t be effectively maintaining battery charge while on in a driving scenario via a plug. The goal of charging is to replenish the battery, and driving expends battery power.
- Safety Concerns: This is the biggest barrier. Charging involves high voltages. Driving a vehicle while connected to a power source is a significant safety hazard for the vehicle occupants, the public, and the charging equipment.
The Role of the Engine in Hybrid and Extended-Range Vehicles
It’s important to differentiate between a pure EV and hybrids or range-extended EVs.
Traditional Hybrids
Traditional hybrids (non-plug-in) have a small battery that is primarily charged by regenerative braking and by the gasoline engine itself. The engine’s output is used to power the car directly or to charge the battery, which then assists the engine. You don’t “plug in” a traditional hybrid to charge its battery from the grid.
Plug-in Hybrids (PHEVs)
As discussed, PHEVs can be plugged in. When the battery is depleted, the gasoline engine takes over or assists. You can charge a PHEV while the engine is off, which is the most efficient way. Idling and charging EV (specifically a PHEV with its engine on) is generally discouraged due to inefficiency.
Range Extenders (Series Hybrids)
These vehicles are electric vehicles at their core, with the engine acting solely as a generator. The engine runs to keep the battery topped up. So, in a way, you are charging electric car with its own engine running, but it’s an integrated system designed for this purpose.
Maintaining Battery Charge While On: What Does It Mean?
When thinking about maintaining battery charge while on, it’s crucial to consider the context:
- For BEVs: “On” means the electrical systems are active. The battery’s charge is maintained by plugging into an external source. There’s no internal engine to keep it “on” in the traditional sense.
- For PHEVs: You can maintain battery charge while the car is “on” (engine off) by plugging it in. If the engine is running, it can contribute a small amount, but it’s not the primary or efficient method.
- For Range Extenders: The engine’s sole purpose is to maintain battery charge while the vehicle is operating.
Common Misconceptions and What the Terms Really Mean
The confusion often stems from the terminology and the different types of electrified vehicles.
- “Car charging while running”: This most commonly refers to regenerative braking in EVs and hybrids. It can also, in a limited sense, refer to range extenders. It does not mean plugging in a BEV and driving it.
- “Idling and charging EV”: Primarily applies to PHEVs. It’s technically possible but inefficient to charge a PHEV while its gasoline engine is idling.
- “Using car engine to charge battery”: This is the primary function of the engine in range-extended EVs. For PHEVs, it’s a secondary, less efficient method compared to plugging in.
- “Charging while driving”: This is regenerative braking. You are not plugged in.
- “EV charging while engine runs”: This is the defining characteristic of range-extended EVs.
- “Can I keep my car running while charging?”: For BEVs, the engine isn’t relevant. For PHEVs, yes, but it’s inefficient.
How EVs Manage Power and Charging
The sophisticated battery management system (BMS) in an EV is key to all of this.
Battery Management System (BMS)
The BMS is the brain of the battery pack. It monitors:
- State of Charge (SoC): How much energy is in the battery.
- Temperature: Critical for battery health and performance.
- Voltage and Current: To ensure safe charging and discharging.
- Cell Balancing: Ensures all battery cells are charged and discharged evenly, maximizing battery life.
When plugged in, the BMS communicates with the charging equipment to determine the appropriate charging rate. If the vehicle is “on” but not driving, the BMS will manage the power flow for charging.
Internal Combustion Engine (ICE) in PHEVs
When a PHEV’s engine is running, it’s typically controlled by the vehicle’s powertrain control module.
- Engine-on Charging: If the battery is low and the car is running, the engine might be directed to generate more electricity than needed for immediate propulsion, thus charging the battery. However, the efficiency is low.
- Engine as Generator: In range-extended vehicles, the engine is always a generator. Its sole purpose is to produce electricity to charge the battery.
Safety First: The Paramount Importance of Proper Charging
It cannot be stressed enough that charging an EV should only be done using approved charging equipment and methods.
Dangers of Improper Charging
- Fire Hazards: Using damaged cables, incorrect adapters, or charging in unsafe conditions can lead to overheating and fires.
- Electrical Shocks: High voltages are involved. Improper grounding or faulty equipment can be extremely dangerous.
- Vehicle Damage: Attempting to charge in ways the vehicle is not designed for can damage the battery, charging port, or other electrical components.
This is why you will never see manufacturers endorsing or designing BEVs to be charged while driving on public roads. The safety risks are too high.
Frequently Asked Questions (FAQ)
Here are some common questions related to charging EVs while they are “on”:
Q1: Can I charge my electric car while it’s driving?
A1: No, you cannot plug an electric car into a charging station and drive it simultaneously. This is unsafe and not how the systems are designed. However, EVs do recapture energy while driving through regenerative braking, which effectively “charges” the battery as you slow down.
Q2: Is it okay to leave my EV plugged in while the car is on?
A2: For a pure Battery Electric Vehicle (BEV), the concept of “the car is on” without driving usually means the accessory systems are active. You can certainly charge it while it’s in this state, as it’s essentially the same as charging while parked. There’s no engine to worry about.
Q3: Can a plug-in hybrid charge its battery while the engine is running?
A3: Yes, a plug-in hybrid (PHEV) can technically charge its battery while the gasoline engine is running. However, this is generally inefficient because the engine consumes fuel, and the amount of charge added is often minimal compared to plugging into an external source. It’s best to charge a PHEV with the engine off.
Q4: What is regenerative braking?
A4: Regenerative braking is a system in EVs and hybrids where the electric motor acts as a generator when the driver decelerates or brakes. This converts the car’s kinetic energy back into electrical energy, which is then stored in the battery. It’s a form of charging while driving, but it happens passively.
Q5: Are there cars that charge their battery using their engine while driving?
A5: Yes, vehicles with range extenders or series hybrid powertrains use their internal combustion engine solely as a generator to charge the battery, either while stationary or while driving. The engine does not directly power the wheels.
Q6: Is it safe to charge my EV while the engine is running?
A6: For pure EVs, this question is moot as they have no engine. For PHEVs, while technically possible to plug in while the engine runs, it’s not recommended due to inefficiency and potential strain. Safety is paramount, and EV charging is designed for stationary use with the engine off.
Q7: Does idling and charging an EV consume a lot of battery?
A7: If you are referring to a PHEV with its engine idling while plugged in, the engine itself is consuming fuel. The car’s electrical systems will draw a small amount of power to operate, but the primary concern is the wasted fuel from the idling engine, not a significant drain on the battery from idling.
Conclusion: Charging Smart for a Sustainable Future
The question “Can I charge my car while it’s on?” is multifaceted. For pure Battery Electric Vehicles (BEVs), the answer is effectively yes, in that you can charge them when the car’s electrical systems are active (accessory mode), but there is no engine to keep running. The primary method is always engine off charging electric car systems through a plug.
For plug-in hybrids (PHEVs), while it’s technically possible to charge while the engine runs, it’s inefficient and not the recommended practice. The optimal way to ensure maintaining battery charge while on for a PHEV is by plugging it in when the vehicle is stationary and the engine is off.
The concept of using car engine to charge battery is a core feature of range-extended EVs, where the engine functions exclusively as a generator. And the ubiquitous charging while driving we see through regenerative braking is a passive energy recovery system, not a method of actively plugging in and driving.
Ultimately, whether you’re dealing with a BEV, PHEV, or a traditional hybrid, the best practices for charging involve leveraging external power sources when the vehicle is stationary and its propulsion systems are not actively engaged. This ensures safety, efficiency, and the longevity of your vehicle’s battery. By clarifying these distinctions, we can all make more informed decisions about charging our electric and electrified vehicles.