Electric Car Technology

When it comes to electric vehicles, you don't say, "What's under the hood?" There is, no doubt, something under an EV's hood, and it's an electric motor. The electric motor drives the wheels and makes the car go. But the most compelling piece of technology in an EV is its battery. The battery determines how far you can drive, how fast you'll accelerate, and perhaps how long you'll own your EV. In other words, the battery in an electric vehicle is kind of like a regular car's gas and engine all rolled into one.

How does a battery take on so much responsibility? Allow us: We've pulled the lid off a CODA battery so that you can better understand any EV's true driving force.

SIZE AND LOCATION

EV batteries are, relative to the battery you're accustomed to seeing in a gas-powered car, much bigger and heavier. Our battery is approximately six feet long and four feet wide. Fortunately it's only about six inches thick. We put it directly underneath the passenger compartment, where its approximately 700 pounds of cells are low to the ground and can enhance the vehicle's handling.

CLIMATE CONTROL

Battery engineers will tell you that batteries are like people—at least people from the tropics. They like to be in environments ranging from approximately 60 to 100 degrees Fahrenheit. CODA's battery will operate over a much wider range—from 0 degrees Fahrenheit to well past 120.To keep the battery happy, we control the climate inside its aluminum and polymer housing. The same heating and air-conditioning devices that regulate the car's interior temperature work separately to keep the battery at an optimal operating temperature.

BUILT TO LAST

EV manufacturers increasingly use lithium-ion batteries (as opposed to, say, "nickel-metal hydride" batteries), because Li-ion batteries pack a lot of energy for their weight, and discharge very slowly when not in use. While the performance of Li-ion batteries designed for laptops or cell phones is somewhat peaky and degrades relatively quickly, the larger, higher capacity car batteries have been built for steady performance over the long haul. Our internal lab testing indicates that our battery's "run time" will remain very consistent for an estimated eight years or more (based on normal driving habits and conditions). Nonetheless, real-world results may vary significantly.

BEHOLD THE GRID

Our battery has 728 "cells" from overhead, it looks like a grid stuffed with many silvery metal packs of large playing cards that have been placed on their ends. Inside each of these "packs" are the cells, where the action takes place. We can't tell you everything about the cells, for the same reason Coca-Cola doesn't divulge its formula.

DELIVERING THE POWER

What we can tell you: When you press the accelerator of an EV, you complete an electrical circuit that causes lithium atoms inside of each battery cell to lose electrons. What are now called lithium ions (an ion is a "charged" atom because it has either lost or gained electrons) travel through the cell, moving from a carbon material into a liquid called an electrolyte and then into another material—lithium iron phosphate. Electrons, however, don't follow the lithium ions. They won't move through the electrolyte. Instead, the electrons travel a different path through the car's interconnects and wiring, and generate power in the engine before rejoining the lithium ions in the lithium iron phosphate. Each of the battery's 728 cells contains innumerable lithium atoms, and each atom loses one electron in becoming an ion. A trillion trillion electrons flowing through the wires create approximately one Amp, and sometimes the CODA's system experiences peak currents of 500 Amps. That's a lot of electrons.

ORANGE FOR A REASON

Every high-voltage wire in our car—in any EV—runs through bright orange housing. You won't get hurt by touching the housing, or even disconnecting wires (which we do not recommend). The car's battery management system constantly monitors the car's electrical system, and will go so far as to completely disable the battery if it senses any high voltage "faults." Sensors all over the car also convey faults back to the battery's brains. In fact, the same sensors that set off airbags will immediately cause the battery to disconnect.