Last week at CES 2016, General Motors CEO Mary Barra unveiled the official production version of the 2017 Chevrolet Bolt EV long-range electric car. Closely based on the Bolt EV concept car we saw last year at the 2015 North American International Auto Show (NAIAS) in Detroit, it features an always-on Internet connection, an estimated 200-miles of range, and comfortably seats four adults (five if the three in the rear are good friends).
But while GM was keen to let journalists experience the Chevy Bolt EV first-hand last week on a small enclosed test-track at CES, it kept the details of the car’s custom-designed electric motor and lithium-ion battery pack a closely-guarded secret, only confirming a sub 7-second 0-60 time and an expected EPA range in excess of 200 miles per charge.
This morning in Detroit on the opening day of NAIAS 2016, GM finally shared those all-important technical specifications, confirming that the 2017 Chevrolet Bolt will come with a 60 kilowatt-hour lithium-ion battery pack and a 150 kilowatt electric motor.
Battery first. Built and supplied by its strategic partner LG Electronics, the massive 60 kilowatt-hour nickel-rich lithium-ion battery pack that will power the Chevrolet Bolt EV is twice the capacity of the 30 kilowatt-hour lithium-ion battery pack currently being offered by GM’s nearest rival Nissan in its 2016 Nissan LEAF SL and 2016 Nissan LEAF SV models. Made up of 288 discrete cells arranged in 96 cell groups, ten modules and five sections, the entire battery weighs just 960 pounds (435 kilograms) in weight and uses a brand-new cell chemistry which GM says requires a smaller active cooling system than previous-generation LG Chem packs. It can provide 160 kilowatts of instantaneous power, says GM, enough to provide a full 150 kilowatts to the Bolt EV’s electric motor and leave an additional 10 kilowatts for ancillaries.
Although GM hasn’t given an official energy density figure for the pack, simple math suggests a battery energy density of around 137 watt-hours per kilogram. That math however would be wrong, since we’re guessing the quoted battery weight from GM includes ancillary hardware such as battery management modules and power electronics within the finished battery pack itself. Since those extras can significantly increase pack weight, we’d suggest the actual energy density of the cells used is far closer to 200 wh/kg than rudimentary math would suggest.
GM says that each battery cell is 3.9 inches (100 mm) high and 13.1 inches (338 mm) wide, allowing the battery pack to be shaped to fit underneath the floor of the Chevrolet Bolt to maximize cabin space. In keeping with good design practices and appropriate safety protocols, the entire battery pack is located within the wheelbase of the Bolt EV, with a bulge towards the rear of the pack where the rear seats are. This bulge allows GM to fit in extra cells but also to house some of the power electronics. In total, the battery pack takes up 285 liters (10.06 cubic feet) of space.
With such a large number of cells squeezed into a small space, GM says the Bolt EV uses a liquid active thermal control cooling system to keep the battery operating at peak efficiency, but also notes that the improved cell chemistry “allows the Bolt EV to maintain peak performance in varying climates and driver demands.”
Those eager to hear about the Bolt EV’s charging options will be please to know that a 7.2 kilowatt on-board charger is included as standard, allowing around 50 miles of charger to be added to the Bolt EV in two hours from a standard Level 2 charging station. Meanwhile CCS quick charging is optionally available using the SAE Combo connector, adding up to 90 miles of range in 30 minutes in ideal charging conditions.
This suggests a 50 kilowatt CCS charging system is being used on the Bolt EV, which will be a little disappointing to those hoping that GM was going to use a more powerful 100 kW CCS charging connector. Given the lack of 100 kW CCS charging stations in the wild however, we can forgive GM for choosing this option, since we’d guess few will want to use the Bolt EV for trips in excess of 300 miles in a single sitting — and those who will will most likely want to take a full hour off to have a meal or stretch their legs before getting back into the car anyway.
In line with other automakers, GM will be offering an 8-year, 100,000 mile limited warranty on the battery pack, the details of which have yet to be announced.
Onto the motor. Mounted at the front of the car, the Bolt EV’s electric motor has been designed specifically by GM based on its previous experience with electric motors in the GM EV1, Chevy Volt range-extended electric car and Chevy Spark. Built by LG Electronics under its partnership with GM on the Bolt EV, the motor is rated to deliver a maximum power of 150 kilowatts to the wheels at up to 266 pound-feet of torque. This not only helps the Bolt EV accelerate to 60 mph in less than 7 seconds, but also helps it carry around the extra weight of that 60 kWh battery pack.
As with other electric cars on the market, there’s a single-speed fixed-ratio gearbox, which GM says gives a final drive ratio of 7.05:1.
Controlling the motor is what GM calls “Chevrolet’s first Electronic Precision Shift system.” While that may sound like a gearbox, it’s actually a fancy name for an electronic motor controller system which sends electronic signals to the vehicle’s drive unit to manage power and torque delivery based on drive mode selection and accelerator position and handles parking pawl and gear selection electronically.
That same system, when used in conjunction with the ‘Low’ drive selector and regenerative paddle mounted on the left-hand side of the Bolt EV’s steering wheel, also makes single-pedal driving possible. User-adjustable regenerative braking — which was a feature of the original EV1 thanks to its ‘coast’ button — makes it possible for drivers to control how much regenerative braking is being used at all times, ensuring that on accelerator liftoff all usable energy is recaptured by the Bolt EV’s electric motor rather than wasted through friction braking.
In city driving scenarios, experienced drivers should be possible to stop the Bolt EV using the user-adjustable regenerative braking without even touching the brake pedal. GM notes however that the system “does not relieve the need to use the brake pedal altogether.”
As we explained last week, GM is committed to bringing the Bolt EV to production this coming October as a 2017 model-year car, with a price tag starting from $30,000 after U.S. government incentives. Now we know more about the car, we’ll have to wait until October to find out if it manages to come in on target with range, price and production schedule.
What do you think of the 2017 Chevrolet Bolt EV? Are you tempted by it? Or would you prefer a larger vehicle with similar specification?
Leave your thoughts in the Comments below.
You can also support us directly as a monthly supporting member by visiting Patreon.com.