As is the case with most Hybrid and EV drivers, just about every Chevrolet Volt and Cadillac ELR owner understands their vehicle on an enthusiast level. At Evergreen, we love sharing our mutual passion for the technological advances these niche vehicles have sparked across the global automotive industry. And as such, we feel it's our professional and civic duty to provide as much educational information regarding these vehicles and their respective powertrains in an easy to read breakdown.
Most owners know or have a good idea about the range and kWh capacity of their respective vehicle, but did you know there were 3 different kWh capacity ratings across the entire Gen 1 line?
Pictured: 2011 Gen 1 Chevrolet Volt Hybrid Battery with the protective cover removed, revealing the modules containing their individual cells as well as the cooling apparatus.
2011: The Beginning
The 2011 Chevrolet Volt was the first model year of the Volt, and it used a 16 kWh lithium-ion battery pack to store electricity and power the electric drive system. The battery pack was located under the center console of the vehicle and consisted of 288 cells arranged in series. Each cell contained a positive and negative electrode, as well as an electrolyte solution that allowed ions to flow between the electrodes.
The total capacity of the battery pack was 16 kWh, which provided a range of about 35 miles on a single charge in electric-only mode. The battery pack was designed to be charged from a standard household outlet or through a dedicated charging station. It could be charged to 80% capacity in about 4 hours using a 240-volt level 2 charger, or in about 10 hours using a 120-volt level 1 charger.
The battery pack was cooled by a liquid cooling system that helped to maintain the cells at a consistent temperature, which was important for maintaining the overall health and performance of the battery. The battery pack was also equipped with a number of safety features, including a thermal runaway protection system and a high-voltage isolation system, to prevent accidents or fires.
The battery pack was designed to last for the life of the vehicle and was covered by an 8-year/100,000 mile warranty. This meant that the battery pack was expected to maintain at least 70% of its original capacity for at least 8 years or 100,000 miles, whichever came first.
2013: A Mild Bump In Capacity
The 2013-2014 Chevrolet Volt uses the same chemistry lithium-ion battery pack to store electricity and power the electric drive system. The battery pack retained its original design and technologies, with a very small increase in overall output.
The total capacity of the battery pack is 16.5 kWh, which provides a range of about 35 miles on a single charge in electric-only mode. The battery pack is designed to be charged from a standard household outlet or through a dedicated charging station. It can be charged to 80% capacity in about 4 hours using a 240-volt level 2 charger, or in about 10 hours using a 120-volt level 1 charger.
The battery pack is cooled by the same liquid cooling system from the 16.0 kWh pack, as well as the standard safety features such as the thermal runaway protection system and high-voltage isolation system, to prevent accidents or fires.
2015: The Final Power Increase The final variant came with the 2015 Chevrolet Volt , which uses a 17.1 kWh lithium-ion battery pack to store electricity and power the electric drive system. All prior safety and cooling systems have remained the same from the previous iterations.
The total capacity of the battery pack was 17.1 kWh, which provided a range of about 38 miles on a single charge in electric-only mode. The battery pack was designed to be charged from a standard household outlet or through a dedicated charging station. It could be charged to 80% capacity in about 4 hours using a 240-volt level 2 charger, or in about 10 hours using a 120-volt level 1 charger.
The Power Source:
The lithium-ion battery cells for the Chevrolet Volt and Cadillac ELR were produced by LG Chem, a South Korean company that is a leading manufacturer of batteries for electric vehicles. LG Chem has a long history of producing high-quality battery cells for a wide range of applications, including consumer electronics, power tools, and electric vehicles. The company operates several battery manufacturing plants around the world and has a strong reputation for producing reliable and long-lasting battery cells.
Pictured: GM Engineers load testing prototype Voltec batteries.
In the case of the Chevrolet Volt and Cadillac ELR, LG Chem supplied the battery cells to General Motors (GM), which then assembled the cells into a complete battery pack at its Brownstown Battery Assembly Plant in Michigan. GM was responsible for the overall design and integration of the battery pack into the vehicle, as well as the testing and quality control of the finished product.
Pictured: The LG Chem supplied lithium-ion cell pouch.
Cell Breakdown: Innovation, Safety, and Reliability
A battery cell delivers electric current as the result of an electrochemical reaction. Electrical current is carried by lithium ions, from the positive electrode (cathode) to the negative electrode (anode) during charging, and from negative to positive during discharging. The ions are small and reside within the crystal structure of the electrode materials. Different electrode materials have different current-carrying capacities, and this affects the storage capacities of the cells. Each of the Volt and ELR's 288 cells is a “building block” within the larger battery module and pack. An individual cell is about the size of a 5-inch by 7-inch (12.7-cm by 17.7-cm) photo frame, is less than a quarter-inch thick and weighs nearly a pound. Each Volt’s battery cell contains a carbon anode (the negative electrode), a manganese-based cathode (the positive electrode) and a safety- reinforced separator, which provides the medium for the transfer of electrical charge ions between the anode and the cathode inside the battery cell. The protective polymer-coated aluminum cover encases the cell, helps prevent gas permeation and improves battery cooling efficiency. Tabs at the top of the cell are used to link the cells within the module.
The LG Chem sourced cell uses a manganese-based cathode chemistry with additives to improve battery life under high-temperature conditions. The battery cell is encased in a polymer-coated aluminum package. This thermally efficient and safe package is designed to be more forgiving under harsh conditions and help reduce the cost and complexity of the battery cooling system.
Numerous measures have been taken to help prevent the safety issues – namely short circuiting and overheating – that have occurred in lithium-ion batteries used in consumer electronics. LG Chem’s exclusive Safety Reinforced Separator consists of semi-permeable membranes separating the electrodes in the cells, which are mechanically and thermally superior to commonly used separators.
Primary, as well as backup battery pack controls, regulate voltage, current state of charge and temperature. Rigorous testing of lithium-ion battery packs in GM’s battery labs and on-road in early engineering development cars did not reveal any safety or performance issues at the time. This obviously hasn't been the case using real-world examples, but overall the majority of the goals established during research and development have come to fruition.