Is an 800 V electric vehicle (EV) system truly superior to a 400 V system? Not according to one EV maker.
Canadian EV expert James Carter recently had an insightful discussion with Jim Castelaz, Chief Technology Officer of Motiv Power Systems. Motiv is an EV manufacturer based in the San Francisco Bay Area.
According to Castelaz, some vehicles may actually benefit more from keeping a 400 V system than transitioning to an 800 V system.
Pros and Cons of 800 V Systems
While the industry has often assumed that an 800 V system offers numerous advantages over the previous industry standard of 400 V, bigger is not always better, especially in certain applications.
Undoubtedly, 800 V systems provide significant benefits such as faster DCFC charging, lighter wiring, better efficiency at higher speeds, and more efficient power electronics.
However, there are many downsides of 800 V systems that get much less attention. These include their more complex and costly battery systems, their higher-priced components, and their lower efficiency with re-gen braking (which is caused by a higher step-up inverter).
Moreover, 800 V systems can be inconvenient given that most EV charging infrastructure operates at 400 V.
In reality, the choice between 800 V and 400 V systems depends on the specific use case. For applications where fast charging and performance take precedence over cost, like sports cars or long-haul trucks, an 800 V system is preferable.
On the other hand, in cases where cost outweighs charging speed or performance, a 400 V system generally proves to be more effective.
Why Motiv Switched to 400 V
Castelaz’s surprising revelation was that Motiv actually switched from an 800 V to a 400 V system after realizing that medium-duty vehicles perform better at the lower voltage. Motiv reached this conclusion when it noticed that battery RFPs always priced an 800 V battery higher than a 400 V battery.
Consequently, Motiv thoroughly evaluated the entire system and its impact. For its medium-duty vehicles that operated in the city and charged overnight, the advantages of an 800 V system were not applicable. The 800 V system even had a slight negative effect on in-town efficiency.
As a result, Motiv strategically opted for the cost savings and improved efficiency in urban settings offered by a 400 V system. The company even developed a unique ultra-high torque 400 V electric motor. This motor delivers more torque at a significantly lower cost compared to an 800 V system.
It’s worth noting that Motiv’s approach may not always be suitable for light-duty cars and large trucks. Nevertheless, it remains noteworthy that Tesla has continued to use a 400 V system thus far.
Image Source: EVMagz, https://shorturl.at/bEV19
