Battery swapping is a form of energy replenishment of present day EVs and refers to the process of replacing a depleted or partially depleted battery pack in an EV with a fully charged one, typically at a dedicated battery swapping station. This approach is used in some EVs as an alternative to charging the vehicle’s battery pack via a charging station. This need becomes extremely critical in a world which is trying to migrate from more than century old proven technology of ICEVs to EVs. It will only be comparable to present day gas filling station, when the energy replenishment of EV is comparable to the present day fuel filling in ICEVs. The EVs will then only be ready for long range of travel and mass acceptably.
When we talk about battery swapping, it indirectly means energy swapping only which is store in batteries. For understanding this process of energy swapping, we need to travel back a bit more in the history of mobility, as it evolved from the early days of civilization. Energy swapping, per se has been a big challenge since the time humans found faster alternative to move as compared to walking. It was the time when animals (primarily horses) were used for long distance movements or for load carrying. Since, the animals by nature have limited range of travel due to their biological & physical constraints (they need rest & food to recoup their energy), arrangements were made at regular distance in those early time to change these animals (or in other words swapped) to ensure that the journeys could be completed at a steady pace. Such relay stations also had a set of trained people to keep these animals, fit & healthy. These places allowed the tired animals to rest and recover, while allowing people to continue their onwards journey by using new animals, without breaking their journey. This in a way, was the very first energy swapping station albeit of a different kind where depleted energy source (tired animals) was swapped with rejuvenated energy source (well rested & well fed animals). The pattern continued during the times of steam engines, when the energy swapping/ refilling was done in the form of loading of coal & water which were required by the steam engines. During this time, complex network of coal & water replenishment system were evolved. This refilling of coal & water was also a form of energy swapping for the mobility machines of those times. Historically, horse changing (swapping) & Coal/ water refilling system were important aspects of transportation and logistics before the advent of the automobiles. This changing of horses was a skill, so was the coal & water filling, requiring good coordination, as well as knowledge of the multiple systems & could truly be called the origin of present day battery (energy) swapping for future EVs. Now, considering the similarity of these energy charging & gas refilling as a process of energy replenishment, we need understand the challenge of EVs since early 1900s when they were ruling the mobility world.
Present Day Battery (Energy) Swapping
Coming back to modern day EVs, the battery swapping has great level of similarity with these energy swapping systems of by gone era & conforms to same purpose – as it was in good old days when the horses were replaced/ coal-water was replenished, to fasten the journeys & reduce the idle time. The battery swapping of present day EVs, need to serve the same purpose & in the late 19th century, many automotive companies had begun experimenting with the idea of quick replacement
The Milburn Wagon Company (founded in 1848 in Toledo, Ohio), was one of the more successful electric car makers of those time, producing thousands of vehicles between 1914 and 1922. In 1915 they introduced a battery swap-out system, which had batteries on rollers that allowed the owner to “roll out” the discharged batteries and “roll in” the charged ones. President Wilson’s Secret Service staff used Milburns. Later in 1923, General Motors (GM) bought the Milburn factory and used it to make Buicks cars, yet the Milburns were produced on a “custom-order” till as late as 1927. Another company, the Electric Cab and Carriage Service which was launched in New York in 1897 by two Philadelphia engineers, Henry Morris and Pedro Salom, and backed by the Electric Storage Battery Company. In 1899, as the sales increased, it renamed itself the EV Company (EVC).
Unfortunately, in those times, most of the batteries were with LABs (Lead Acid Battery) which were disproportionately heavy, weighing around 1,600 pounds each, and the cars’ shell could barely cope with this added weight. Moreover, these LABs were prone to leak corrosive fluids damaging the car bodies. Since the electricity was a new invention in early 1900, the charging/ swapping facilities were also limited. It was time that when a EV drove into the station, technicians had to pull out the 2.600 kg battery tray, using a hydraulic piston and then used an overhead crane to lift it from the table and deposited it in the charging room. The new battery was put back using the reverse process for the cab to move out on roads.
In 1907, predictably, EVC folded and it was a year later when Henry Ford launched his famous “Model T”. Some of these electric cabs continued to run in New York City until 1912, BUT by 1919 the EVs market share fell to just 1% of all commercial vehicles in US, and virtually no private EV cars due to massive success of “Model T” and discovery of cheap oil in Texas (period known as “Texas Oil Boom”). However the charm of EVs never died and the search continued to find a lightweight battery alternative to the heavy LAB. It was a quest that took almost seventy years to reach its goal when Lithium Ion Battery (LIB) could be commercially made available. However, it is understood that there were still many converted EVs which were used taxis in Spain till WW-II – these converted EVs were using LAB due to “Shortage of Fuel” in Europe. This system was the earliest examples of “Exchangeable Battery Service” system developed by the French company “La Societe des Moteurs Bollée” in the early 1900s, which allowed EV drivers to quickly “swap out” depleted batteries for fully charged ones at designated battery-swapping stations.
Unfortunately, affordability of ICEVs & cheap oil did not allow it to gain widespread acceptance. Around the same time (between 1910~1924), an electrical utility company in US, by the name of Hartford Electric Light Company , through its sister company GeVeCo battery service, was serving electric trucks with what is known as the earliest battery swapping service of modern times. The vehicle owners purchased the vehicle, without a battery, from General Vehicle Company (GeVeCo), part-owned by General Electric. The energy was purchased from Hartford Electric & batteries were charges which were sold as exchangeable battery.
Both vehicles and batteries were designed to facilitate a fast exchange. The owner paid a variable per-mile charge and a monthly service fee to cover vehicle maintenance and storage. These vehicles covered more than 6 million miles despite the fact that early Milburns only had a useful range of 90 to 120 kms. A 1918 literature advertisement stated “The batteries are now on rollers that operate on tracks, simply roll out the discharged ones and roll in the freshly charged set.”
A similar service was operated for owners of Milburn Light electric cars in Chicago . In the 1970s, Mercedes tested battery swapping and built about 40 electric buses with a manual horizontal battery swapping system (see figure 2) but concluded that the technology was not safe. Due to these quality concerns, the project was not continued . Thomas Weber, the chief of R&D at Mercedes, said that the system tested by them was very dangerous, as electrocution could occur easily during the manual change. They tested these 40 trucks very rigorously, with a manual horizontal battery swapping system. Back in 1970, when the electronics was primitive Weber had a point on electrocution. Added to the precautions of electrocution, there was the issue of the battery’s quality.
The concept of an intelligent charging and discharging mechanism, telling the customer what the state of the battery is, must have been out of science fiction in those times, so was to tell about the charging station, it battery parameters and reliability for a next minimum of miles. Weber said that every electric car has to have its own battery and this should have an autonomy of about 125 miles, being recharged in a maximum of 15 minutes up to 80%. Weber also said that the battery technology to achieve this won’t be commercially viable until 10 years from now (remember it was 1970).
Above are the cut sections of chassis of early EVs by General Vehicle (GeVeCo) chassis from Long Island City, New York, 1911 with electric motor in the rear, with chain drive of rear wheel & battery pack mounted at bottom for easy replacement.
Evolution of Lithium-Ion Battery (LIB)
Lithium is the lightest of all metals and has the greatest electrochemical potential to provide the largest energy density for weight but Lithium metal also has inherent instability during charging when used in the battery. In early 1970, M. Stanley Whittingham discovered the process to control this charging instability. However, he could not make this rechargeable lithium battery a practical one. During 1974~76, a process of reversible intercalation in graphite and intercalation into cathodic oxides was discovered by J. O. Besenhard who proposed its application in lithium cells. The research work continued on these cells and in 1991 when a Japanese team at Sony, led by Yoshio Nishi who successfully released the first commercialized lithium-ion battery (LIB). The development of LIB technology was considered to be so revolutionary that in 2019, the Nobel Prize in Chemistry was awarded to John Goodenough, Stanley Whittingham, and Akira Yoshino “for the same. Though these batteries are called LIBs, in real terms they do not have any Lithium as metal but as an intercalated lithium compound. These LIBs are extensively used in modern EVs, however, battery technology analyst Mark Ellis of Munro & Associates sees three distinct LIB form factors & their combination that would be used in future EVs: a) cylindrical cells (e.g., Tesla), b) prismatic pouch (e.g., from LG), and c) prismatic can cells (e.g., from LG, Samsung, Panasonic, and others).
Compared to any other battery technology, LIB technology had many advantages such as high energy density, no need for prolonged priming when new, relatively low self-discharge, low maintenance, can provide the very high current needed during quick acceleration, no memory & also higher cell voltage (3.6V) which compensated few of its demerits such as it is subjected to aging, even if not in use, requires protection to maintain voltage and current & it is expensive to manufacture9 albiet the cost is coming down as the technology is maturing).
One of the biggest advantages of LIB technology is its flexibility in size & form factor. The LIB can be manufactured is shape & size needed to meet any specific requirement with desired working voltages & energy densities.
Return of EVs With Swappable Batteries
With the battery technology (LIB) available, offering excellent energy density & also flexibility creating a battery with unbound form factor, in 1993, Suntera developed a two-seat 3-wheel electric vehicle called the SUNRAY, which came with a battery cartridge that could be “swapped out” in minutes at a battery-swap station. In 1995, Suntera also added a motor scooter. The company was later renamed Personal Electric Transports (PET). After 2000 the company developed an electric bus. In 2004, the company’s 3-wheel stand-up EV won 1st place at the 5-day long American Tour de Sol electric vehicle race. Unfortunately, the company closed in 2006. Some smaller auto makers attempted to popularize battery swapping with individual cities but could not succeed. Zotye Auto built a fleet 15 of M300 EV hatchbacks for a taxi fleet in Hangzhou, China. In 2011, one of these vehicles burnt after the battery pack in the trunk caught fire. An investigation later found that fault in the battery and also pointed out that the battery connecting terminals had worn out due to repeated loading and unloading of charged battery packs.
In recent times, another company which tried to revive the battery swapping albeit in different way, was Better Place, a company started by Shai Agassi of Israel in 2007 when it developed and started settling battery charging and battery switching services for electric cars. The company’s setup was able to replace depleted batteries with fully charged ones at designated battery swapping stations very quickly. Despite being an old idea in an age of mobile phones, his idea of quick battery swapping for electric cars was an instant hit, and since it was right time when venture capitalists were looking for some great idea, it is found in Better Place. The funds started pouring in & the company began to expand rapidly throughout the world. With growth beyond expectation, Better Place announced deployment of EV networks in Israel, Denmark and Hawaii in 2008 and 2009. The company planned to deploy the infrastructure on a country-by-country basis, and went on to initiate talks with more than 25 additional regions around the world. Australia, Ontario, Oregon, and California also announced deployment of its own EV networks.
Riding on success, in January 2008, Better Place announced a memorandum of understanding with Renault-Nissan to build the world’s first Electric Recharge Grid Operator (ERGO) model for Israel. Under the agreement, Better Place would build the “Electric Recharge Grid”, and Renault-Nissan would provide the custom built EVs.
Unfortunately the growth of Better Place was much hyped and unsustainable over the long period due to the high investment required to develop the charging and swapping infrastructure. Market penetration of Better Place was significantly lower than originally predicted by Shai Agassi, who expected 100,000 cars on Israeli roads by 2010 which never crossed 1,000. A total of 948 Better Place branded Fluence Z.E. cars were deployed in Israel and around 400 units sold in Denmark by May 2013, when Better Place filed for bankruptcy.
Under Better Place’s business model, the company owned the batteries of Fluence Z.E. Customer never owned the battery and hence there was a risk of being left with a useless car in case Better Place was unable to supply a charged battery under replacement plan. It must be noted that the Renault Fluence Z.E. was the electric version of the Renault Fluence compact sedan, part of the Renault Z.E. program of BEVs. It was unveiled by Renault at the 2009 Frankfurt Motor Show. The Fluence Z.E. was fitted with a 22 kWh LIB which allowed it travel range of about 185 km (with maximum speeds up to 135 kmph). It was the first modern electric car known to be enabled with battery swapping technology and was deployed within the Better Place network in Israel and Denmark in 2012. Fluence Z.E. was built at the Oyak-Renault plant in Bursa, Turkey & as it was phased out, a fixed-battery version called Renault Samsung SM3 ZE was launched in South Korea. It was one of the most popular electric cars in South Korea in the mid-2010s, with thousands sold through 2017. Global sales totaled 10,600 units through December 2019, mostly composed of SM3 Z.E. units.
Present Day Scenario
Now with evolution of battery technologies and by being in operation for quite some time the battery swapping technology has also seen many cyclic changes. The recent evolution of whole eco-system, battery swapping is becoming a practical solution for the mass EV market, with better load & energy management. Today, with rising number of EVs on the roads, it is gaining popularity as new age EVs have also evolved into an accepted alternative of ICEVs. Many companies like NIO Power (China), Gogoro (Taiwan), Immotor (China), Aulton (China), and Sun Mobility (India) are the leading players and are now creating dedicated battery swapping stations to make it easier for drivers to switch out their batteries. The Battery swapping technology today is a highly innovative field both from core electronics point of view to highly complex power gird & load management as well as energy balancing (between conventional & renewable energies) point of view. Overall, while battery swapping technology has the potential to improve the convenience and cost-effectiveness of EVs, more testing and research are needed for its scalability, ease of operation with safety to make improve its acceptability.
To be continued…
- https://youtu.be/NZ-ktYKazEs, Electric Vehicle Video
from 1943 Spain
Prabhat Khare holds BE (Electrical) & a Gold Medalist from IIT, Roorkee. He is an Automotive (EV) & Engineering Consultant, as well as a Technology Article Writer. He is a Certified Energy Manager (BEE) & Lead Assessor for ISO 9K, 14K, 45K & 50K. He can be reached at LinkedIn: https://www.linkedin.com/ in/prabhatkhare2/.