True to our philosophy of using as many products from Swiss suppliers as possible, we set out to find suitable batteries for the Terren. While researching for the ideal system, we came across ecocoach AG. The company, based in Brunnen SZ, operates with its division ecovolta as a developer and producer of high-performance batteries for electric vehicles. After initial discussions and technical clarifications, it was clear that ecovolta would be more than just our battery supplier. The brand is sponsoring us with nine evoTractionBattery 100/10 battery packs of the latest generation. In addition, ecovolta is acting as Peak Evolution’s official innovation partner.
The choice of battery technology was central to the development of the TERREN. Due to the market situation, we had to focus not only on quality but also on availability and modularity. In the highly competitive industry, as a small vehicle manufacturer it is sometimes not even possible to get a response to a request from a large battery manufacturer, let alone a battery.
Fortunately, there is a very lively and innovative industry in this field in Switzerland.
Because of the technological orientation and the various references of similar projects, we came across ecovolta, headquartered in Brunnen SZ. It is a division of ecocoach AG, which has extensive experience in the production and integration of stationary battery storage, energy as well as charging management systems.
With its storage systems called evoTractionBattery, ecovolta takes an innovative and unique approach to build battery systems for a variety of special applications quickly and at low cost.
Typically, a single battery consisting of several modules is assembled for electric vehicles, with a shape that optimally fits the vehicle. The developed battery packs are then validated and tested to obtain the required system-level certificates. These tests can quickly cost a substantial amount of money.
Ecovolta follows an approach that allows for cost-optimal production on the part of the vehicle manufacturers. The individual, standardized battery packs have been extensively validated and have all the necessary certificates. The packs can then be used in parallel and in series in the desired configuration. In this way, different capacities and voltage levels can be achieved. The voltage of the individual packages is 48 or 96 volts, which means that many applications can already be covered.
The storage concept of the TERREN expedition vehicle has a special feature that made the evoTractionBattery system the clear favorite. The vehicle, which will later be produced in series, is operated at a voltage level of 400 V. This corresponds to one of the market’s standard voltage levels. However, such systems are designed for a certain maximum operating altitude. This is usually 4000 meters above sea level. The insulation distances between non-insulated, live parts within the devices are calculated in such a way that no arcing and thus short circuits occur up to this maximum altitude. However, at 6893 meters, the PEAKE EVOLUTION world record is far above this limit and the air pressure is only 40% of that at sea level. With decreasing air pressure, however, the dielectric strength of the air decreases and larger isolation distances would be necessary.
This situation left us with the following options for the Peak Evolution project:
- optimize all devices for a lower air pressure in a costly custom manufacturing process
- reduce the operating voltage level. Lower voltage = shorter arc
After a risk analysis and assessment of the financial impact on the project, the first option was out of the question. Of course, we could have ignored the risk and relied on the safety margins that had been put in place. However, in our expedition, safety is paramount. Therefore, we could only set the voltage range lower. Only thanks to the evoTractionBattery we are able to cover the voltage for both applications.
Technology and configuration in detail
Nine evoTractionBattery 100/10 with a gross energy of 10 kWh each and a voltage of 100 volts are installed in the TERREN expedition vehicle. In contrast to the late series configuration (4s3p for 400 V and 120 kWh), they are connected in 3s3p format, which results in a total voltage of 300 volts and a cumulative gross energy of 90 kWh. Each battery pack weighs 59 kg, giving an energy density of 163 Wh/kg. The cell chemistry is lithium-ion NMC (nickel-manganese-cobalt-oxide).
This configuration is rarely found on the market and is due to the environmental conditions for the record attempt. In order to operate the vehicle at a voltage level of 300 V, special adaptations of the hardware and software are therefore necessary. Ecovolta accepted this engineering challenge with conviction. And that’s not all: the company also sponsors the battery packs for our world record attempt.
What else speaks for ecovolta batteries?
The round cells used with lithium-ion NMC cell chemistry promise a high energy density. This means that they have ideal capacities in a small installation space. The battery packs are also fast-chargeable. This means that the later series-production vehicle is quickly ready for use, even in shift operation. The high discharge capacity favors permanent use for performance-intensive on- and off-road applications. The battery packs also require no periodic maintenance. The cycle stability of the premium cells, the automotive-proven BMS and the robust design favor a long service life and consequently optimal Total Cost of Ownership (TCO).
We would like to sincerely thank ecovolta for their active involvement with PEAK EVOLUTION, as it is a huge leap forward for us to secure the financing and implementation of the TERREN transporter!
For more technical details about the battery, how to handle the climatic conditions and how to charge the battery, please feel free to contact us or ecovolta directly.
