For all of the good that electric cars bring to the table, it may be hard to envision there being any downsides. After all, who wouldn’t want a car that eliminates visits to the gas pump, can ostensibly last a lifetime with reasonable care, and has none of the harmful emissions that come with ICE vehicles? The answer may be towing capacity, as electric cars’ current ability to haul heavy loads leaves a lot to be desired. But why?
Electric cars are bad at towing because of energy density. Currently, lithium-ion batteries cannot store enough energy for towing a reasonably-sized car. Although electric cars can tow a high load for a short while, the added energy requirements of hauling the extra weight will rapidly deplete the battery.
While the current towing capabilities of electric vehicles are not great, there is reason for optimism. In addition to the continued improvement of lithium-ion technology, exciting progress in solid-state batteries makes the prospect of micro-sized batteries feasible in the near future. There are also many companies that are in the advanced stages of developing a hydrogen-electric truck and semi, making clean hauling solutions within grasp.
Why Are Electric Cars Bad at Towing?
Electric cars are bad at towing because current lithium-ion battery technology is not capable of packing sufficient energy into a small enough package to make it feasible to fit into a car. As battery technology currently stands, for a lithium-ion battery to house sufficient energy for a major tow, the battery would have to be the size of the car itself.
As you can see, this is not a realistic scenario. While standard batteries used in electric cars are themselves enormous (some weigh up to 1,200 pounds!), even this seemingly gargantuan battery would be capable of towing a 5,000-pound trailer for only about an hour before dying and needing to be recharged. Not exactly comforting if you want to take your pop-up camper to the mountains.
This is because electric cars are designed with efficiency and not towing capacity in mind. Although it is true that the lithium-ion battery does power the vehicle, most electric and hybrid cars use a series of tricks to keep energy consumption at a minimum, including:
- Automatically turning off while resting at stoplights or in idle
- Fabricating the vehicle chassis as lightweight as possible
- An inductive charging system in which the spinning of the axle charges the battery when it is not being used
These energy-conserving tricks are necessary because even the best Tesla batteries can only store just over 100 kWh of energy. However, very little energy is actually needed to move a vehicle in most day-to-day driving scenarios. Therefore, electric cars can go a surprisingly long way on a single charge under normal circumstances.
Why Are ICE Cars Better at Towing?
It is the relative inefficiency of internal combustion vehicles that actually makes them better at towing. A single gallon of gas contains the potential for 33 kWh of energy. If you multiply this by the 23-gallon tank found in many ICE pickups, you will find that a single tank of gas contains the potential for 759 kWh of energy—more than seven times that of the most powerful electric car battery.
This means that for high torque and high horsepower ICE engines, this extra stored energy can be converted into power, giving the vehicle the ability to pull heavier loads for more extended periods.
While this comes in handy for people that frequently tow, it makes many high-powered ICE vehicles terrible for day-to-day purposes. The extra energy potential is lost through the exhaust system, as it will burn through fuel quickly, whether hauling a load or not.
True, fuel economy does marginally improve when the vehicle is not under a heavy load, but most ICE engines get well under 50% efficiency from their fuel. As the ICE vehicle continues to burn fuel when parked, cruising down Main Street, or rolling down a hill, most of the fuel’s potential is lost on purposes for which it was never actually needed.
How Much Energy Does a Car Need to Tow?
Towing needs will vary based on several factors, and there is no precise way to tell exactly how much energy will be required to complete any trip. The following are just a few of the scenarios that may tax a vehicle during a trip:
- The weight of the vehicle
- The weight of the payload (the weight of the stuff being carried in the vehicle)
- The weight being towed (the weight that is being pulled behind the vehicle)
- The grade of any inclines that must be traversed
- The quality of the road surface
- The speed of travel
- The distance of the trip
With that said, there are some ways to estimate the amount of energy needed for an average towing job. Consider the following conditions:
- A Tesla weighing 5,500 pounds
- A 100-mile haul up a 1% grade
- 500 pounds of payload
- A 5,000 pound trailer
- Traveling 75 MPH
With these relatively standard towing conditions, it is estimated that 100.4 kWh of energy would be needed to complete the trip; this uses all of the latest Tesla Model X’s battery capacity and exceeds that of the older models.
Therefore, significant upgrades in energy density will be necessary before electric vehicles can compete with the towing potential of ICE trucks.
The Future for Electric Car Towing
The future for electric vehicle towing is exceptionally bright. The motors in Teslas are already surprisingly powerful, with top-end speed and horsepower rivaling that of some of the world’s finest luxury sports cars. The challenge lies in fabricating a battery that can store enough energy to keep from draining rapidly when the motor is under a heavy burden.
As with everything technologically related, steady progress is being made. The first fully-electric batteries had a range of only around 250 miles, making them unfit for any kind of sizable road trip. Now, the latest Teslas have a range right around 400 miles, rivaling what most standard ICE vehicles can get on a tank of gas.
Even as some opponents argue that the potential of lithium-ion batteries is about tapped out, there are exciting developments in the realm of solid-state batteries.
A solid-state battery has many of the same properties as a lithium-ion battery, with a primary difference being that it replaces the liquid electrolyte with a solid electrolyte. The solid electrolyte allows the battery to have a higher energy density, store more energy, and be more stable.
While there are still some kinks to work out with solid-state batteries, companies like Tesla, Toyota, and Volkswagen have already made significant investments in the technology. Early reports suggest that cell phone-sized solid-state batteries can power a vehicle for up to a 1,200-mile range and be recharged in a matter of minutes. This extra storage capacity will allow electric vehicles to tow for greater distances without the battery giving out prematurely.
Even if solid-state batteries never fully take off, there is also exciting progress being made in the realm of hydrogen fuel. This creates a form of clean-burning fuel that can serve as a hybrid with electric vehicles meant for heavy towing, with prototypes for such semi-trucks already in fabrication.
Electric cars are bad at towing due to the low energy density of lithium-ion batteries. While the motors in electric cars themselves can perform the work, the battery cannot house enough energy to power the motor under a heavy load for very long. Battery technology will need to continue to improve to the point where enough energy can be stored in a small enough package to make electric towing a more feasible option.