General Motors has opened the curtain concealing the battery pack and the drivetrain of the upcoming Chevrolet Bolt.
5/2/16 5:00 am chumakdenis 1
While most of the people are still overexcited about Tesla Model 3 – the total amount of reservation deposits is over incredible 325 thousand – another not less interesting things are happening at around the same time.
One of such things is news from GM.
They’ve opened the curtain concealing the battery pack and drivetrain of the upcoming Chevrolet Bolt EV and this time we have the ‘meat’ – by meat I mean the components that are hidden under the hood.
So, what’s inside, doc?
Inside we have a 60 kWh battery pack that gives vehicle enough juice to run over 200 miles (321 kilometers) on a single charge.
LG Chem’s pack is three times more powerful than Spark’s pack and has plenty of advantages in comparison with other GM packs, but …it’s not perfect (no one is).
For starters, we have to say that it is two times heavier than its predecessor and the whole battery configuration takes almost all available space –the battery is packed incredibly tight.
But we are in here not to discuss minor imperfections, aren’t we?
Let’s return to our muttons.
* 60 kWh of energy
* 200 miles(321 km) of EPA range
* battery weight of 436 kg
* 160 kW power output
* 288 lithium-ion cells (LG Chem)
* 350 V nominal voltage
* eight years or 100,000 miles battery warranty
* DC fast charging capability (at least 50 kW – we don’t know yet for sure whether GM will enable higher power charging if there will be higher power chargers)
Big mamma jamma has some aces in the hole
The most important one is the amount of juice the battery produces – yeap, capacity (60 kWh vs. 18.4), max power (160 kW versus 120), nominal voltage (350 volts vs. 360)…all of these things are so much better.
Of course, it is not as good as Tesla’s 70kWh pack, but don’t forget that Bolt is almost there while Tesla Model 3 will available to buy not sooner than in a year in best-case scenario.
Comparing Tesla's and GM's pack
Tesla uses cylindrical cells in its batteries while the Bolt relies on "landscape" cells, which are long and flat.
In each battery there are 288 of these cells, which are bundled into 96 groups of three, connected in parallel to form the battery pack.
The cells are double-stacked in the last row, taking advantage of the rear seat's height compared to the floor.
Integration is vastly improved over the Spark as well.
The battery is actually a significant structural component of the Bolt.
If the battery were to be removed, the vehicle's torsional rigidity would drop by 28 percent.
Cross-members are built into the battery's tub to better transfer forces across it – in stress tests, only the rear shelf of the battery experiences significant flexing.
Keeping the battery within its ideal operating range is a liquid cooling system using Dex-Cool coolant. All 6.9 liters of the stuff flows through small metal plates underneath each cell module, and the system is tested to handle vibration and g-force well above what's experienced in normal driving situation.
For safety's sake, there are two separate disconnects. For service concerns, there's a manual disconnect hidden underneath the rear seat.
In front of the battery is a rather hefty crash-safety system, which cuts power in a collision, making it safer for first responders.
The battery is capable of DC fast charging at 50 kW using an SAE Combo plug.
At full clip, it'll add about 90 miles(144 kilometers) of range in 30 just minutes. A full charge on a Level 2 charger takes about 9 hours.
GM claimed the cells were packed as tightly as possible. The company even moved several components – power distribution and charging modules, mostly -- to the engine bay in order to give the battery as much elbow room as possible.
Any further improvement to the Bolt's battery must come from cell capacity and efficiency breakthroughs.
As for the warranty, the battery is covered for eight years or 100,000 miles, whichever comes first. It's built to last the life of the vehicle, which GM said is beyond those figures, but declined to get more specific. Despite being such an integral component, I'm told removing it is no more difficult than removing the transmission in a gas-powered car.
The 2017 Bolt's drive unit, which includes the engine and transmission, was built to be as compact as possible while delivering the torque and performance that Chevrolet wanted. The objective was to top the Spark's acceleration, max launch grade and EPA range all at the same time, and Chevrolet delivered (with LG's help).
While Chevrolet engineered the motor itself, LG's responsible for assembling it, which is done in Korea.
This permanent-magnet electric motor weighs only 76 kg – 8 more times than the Spark's motor – , but the Bolt's unit packs have a smaller outer diameter (204 mm vs. 213), a higher peak power density, higher peak axle torque (2,500 newton meters vs. 1,710) and lower peak torque (360 Nm vs. 540).
In terms of transmission fluid, the numbers are better too (2.9 liters vs. 4.2).
The Bolt's motor rotates significantly faster than the Spark's (8,810 rpm max speed vs. 4,500), but that's translated to the road by way of a much higher final drive ratio (7.05:1 vs. 3.87:1).
Less torque doesn’t mean less juice
Despite the lower peak torque, the 2017 Bolt accelerates faster than the Spark.
60 mph(96 kilometers per hour) arrives in fewer than 7 seconds (7.5 for the Spark), 30 mph(50 km/h) comes up in just 2.9 seconds (3.1 for the Spark), and it can launch from a 30 percent grade (28 percent in the Spark).
Range is also up significantly, from the Spark's 82 miles to over 200 miles – fudgesicles,thought Elon.
Overall, the brand-new 2017 Bolt weighs 3,580 pounds, which is about 700 pounds heavier than the Spark.
Nevertheless, it's a larger car – GM actually calls it a crossover – with a much bigger battery, so it's more than Ok for the vehicle like this one.
Plus, GM's/LG's mama jama gives so much juice that it would be insane thing to blame it for something.
Great job, GM – we are looking forward to seeing the vehicle on sale.
Some folks might get all up in arms about the Bolt not having the same kind of flash or panache as Tesla's hot-to-trot Model 3, but after taking a closer look at the parts of the Bolt that most users will never see or (ideally) worry about, it's pretty obvious that Chevrolet isn't half-assing the Bolt one bit.