EV Battery Capacity Drives Automotive Industry

Electrical Vehicle Battery Capacity is the strength and weakness of electric cars and trucks. 

The capacity of the batteries used in vehicles drives their success and failure in the marketplace.  The more capacity, the more range, and the more horsepower for those drivers that live for POWER will drive sales.

Those drivers with a phobia about running out of gas will be even more apprehensive about running out of juice. Unfortunately, one can’t carry a 5-gallon gas back to your vehicle from the local charging station. But, no doubt there will be charging vehicles that can arrive on the scene to rescue started drivers of EVs shortly.

Some figures on electric vehicles’ batteries and performance

Have you ever heard the saying “figures don’t lie, but liars sometimes figure”?  I don’t want to point fingers, but automobile manufacturers are pretty creative in stating the horsepower and range of electric vehicles. Unfortunately, it appears at times that the numbers defy physics.

And we all know that marketing companies never change the spin or embellish the actual numbers. The good news is the EPA, Environmental Protection Agency, rates EV for capacity and range similar to what they have done for years with combustion engines and vehicles.  The difference is that gallons per mile don’t relate mathematically to watts of power per mile.

An ICE gas tank holds 20 gallons of fuel, while an electric vehicle battery pack holds kWh of energy.  Some larger vehicles may contain 30 or even 40 gallons of gas.  Tank sizes might compare with EVs with battery packs rated at 40, 60, or 100 kWh.  

These numbers are not apples to apples.  More like apples to watermelons.  It is possible to relate the energy produced by electricity and gasoline mathematically, but I will leave that to the physics majors.

EV Vehicles Comparison to Gas Vehicles with Miles per Gallon Equivalent

The EPA has tried to make it easier for customers to compare EVs by developing a Miles per Gallon equivalent (MPGe).  They use 33.7 kWh = 1 Gallon of gasoline.  Its combined gas and electric ratings rate a hybrid plug-in vehicle (PHEV).  Check out their top ten fuel sippers for 2022.

The EPA puts the electric vehicle on a dynamo where it runs the car through a range of speeds from 30 - 65 for highway ratings.  For the city ratings, the cars imitate stop-and-go city driving with varying acceleration and braking.  EVs are rated at kWh/100 miles at 65 miles, an hour speed rather than per mile.  

Electrical vehicle EPA label and battery capacity

Battery Capacity is What Drives The Acceptance of Electrical Vehicles

Electric vehicles were built and used before combustion engines in the late 1800s.  The lack of acceptance was now the range of the car. Early batteries could not be recharged and had to be replaced after they ran out of juice.

The early batteries were also hefty and expensive.  They were quiet and discharged to no smoke or fumes but remained a novelty until the 1900s. Then, in the 60s and 70smore electric vehicles came on the scene. The batteries were huge.  They were practical in golf carts and industrial lift trucks that worked 8-hour shifts before recharging. However, the batteries were still too large and heavy to be functional in cars.

Hybrid vehicles, a combination of ICE, internal combustion engines, and electric motors, began to take hold in the 80s.  This combination increased fuel efficiency significantly and solved the issue of charging and limited range.  

Smaller, lighter, rechargeable batteries sparked the interest in electric vehicles as we approached the 20th century.  The development of more robust, lightweight, and higher capacity is the new race for dominance for vehicle manufacturers.

The Real Basics of Battery Capacity

When designing new battery packs for electric vehicles, the primary goal in most cases is to increase the driving range as efficiently as possible. To accomplish this, experts set realistic goals for how far they'd like the car to go. Then they use the battery capacity formula to precisely measure how much power it'll take to get it there. 

Because batteries constantly have energy pulled from them when in operation, many things contribute to their discharge.

Things like acceleration and hard braking all play a role in the actual storage capacity of a battery. The batteries also cannot be entirely drained of energy to prevent damage.

Gross vs. Net 

It is unhealthy for batteries to have all of their energy drawn. When this occurs, the battery becomes damaged or completely fried. That's why it's important to calculate both the total (gross) and usable (net) capacity. 

Gross capacity is the theoretical maximum amount of energy the battery holds. It allows engineers and manufacturers to determine the car’s capabilities and calculate the net capacity. 

Net capacity is necessary to determine the theoretical amount of power a battery needs to store to travel a specific distance. 

Net capacity is the actual amount of energy the car is capable of drawing from the battery. This estimate is made at the manufacturer's discretion and based on many technical factors. For example, many engineers recommend you reserve 10-20%of the total capacity to guard against overcharge and discharge. 

Calculating Battery Capacity for Electric Vehicles

It's estimated that by 2030, 4 million people will start driving electric vehicles in California alone. To make sure drivers are safe in these new EVs, engineers in the field must master their battery capacity calculations. 

A driver won't necessarily have to worry about the actual battery charge, usable capacity, or kW/h per 100 miles to operate their vehicle safely. However, the manufacturer needs to know this information to fully understand the parameters of their car and improve the available technology in the field. 

Depending on your motor, there are several factors to consider when calculating the theoretical battery capacity. These include things like the gross weight, top speed, motor power, the desired range of the vehicle. 

You can find the very complex formulas for calculating battery capacity here at X-Engineer.org.  Battery electric vehicles or BEVs are all about high voltage and current.  Thousands of 4.3-volt batteries are used to reach voltages up to 750V, the current of 1,200 amps or more.  Not a typical flashlight battery.

Suffice to say, and most users will have to depend on EPA and other automotive review sources to decipher what the manufacturers and marketers are telling us about their vehicles. 

The Future of Battery Capacity and the Electrical Vehicles

Battery technology is evolving quickly.  Lithium-ion batteries, solid-state batteries, hydrogen batteries, Giga batteries, and others compete for 1st place in the race for dominance. In addition, vehicle manufacturers race to create the lightest, safest, highest energy density, and longest-lasting batteries.

Work is underway to create a GWh battery pack.  Gigi-watt is 1,000 times a kilowatt.  Does that mean 1,000 times the range of the current battery packs?  Recent advances have set the stage for faster development.

We are beginning to see more electric drones and aircraft.  Solid-state batteries will be an excellent solution for aviation due to their light weight and small size.  

Hydrogen batteries or fuel cells will boom heavy transportation and construction, especially trucks and even trains.

Thermal Management of Battery Systems will Remain Essential.

The creation of power creates heat. Therefore, battery systems will need cooling systems. In addition, regardless of the type of battery to date, batteries need heat to protect them from cold temperatures.  

Interior cabins also need thermal management that often can be supplied by the high voltage and current battery systems that run the motors and drive trains.  Heat-pumps, PTC heater, and Peltier thermoelectric cooling systems run on conventional voltages will remain necessary for creature comforts.

Need to know more about Electrical Thermal Management Systems?  Talk to our experts about your applications and learn how DBK USA can help.

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