Toyota guarantees its Lexus UX300e and its Proace electric transporter with a battery warranty of 1 million kilometers with a service life of 15 years.
The Japanese have thus made a clever move, because up to now the risk with electric vehicles has rather been with the buyers.
Volkswagen is somewhat more cautious in this respect: VW guarantees one percent for eight years or 160,000 kilometers. That reminds me in a way of the Duracell bunny …
Whether the Toyota mileage of 1 million kilometers is actually used or whether the vehicles are operated for 15 years is not that important. It is the message that counts: We take the risk off your hands!
Assuming a range of 400 km for the UX300e, this means about 2,500 charge cycles. For high-quality battery cells, more than 2,000 cycles are now assumed, so that the 2,500 cycles are within the realm of what is feasible.
The risk for Toyota is therefore manageable, the advertising effect all the greater. Quite apart from that, who drives such distances with an e-vehicle? After all, there is the fear of being left behind somewhere in the landscape due to lack of time and infrastructure.
Both when charging the battery on the DC quick charger with up to 100 kW charging power and when discharging it while driving, a 75 kWh battery should be charged to 80% of its capacity within 45 minutes. This leaves time for driving.
But back to the topic …
How do you constructively create such a high number of charging cycles?
The secret lies in the thermal management of the battery!
A cooling concept tailored to the requirements is the prerequisite for the longest possible service life. This ensures an even temperature distribution and prevents local overheating.
Simulations with FEM and CFD are indispensable tools that can be used efficiently during development.
Water-cooled systems have largely prevailed over air cooling. The higher heat flux density of water allows a more efficient and precise temperature control than with air.
However, electricity and water bite each other, so that with water cooling, increased attention must be paid to the tightness. Over such a long period of time, seals age and the original sealing force decreases to a fraction of its original value.
These are exciting topics, as the experience gained with, for example, circuit boards, plastic parts and seals is no longer worth anything in the case of the combustion engine with its 8,500 hours of operation. After all, the e-vehicle is permanently on standby, being driven or charged. In 15 years, this quickly adds up to over 100,000 hours.
Merkle & Partner has been working on the related simulation topics for well over a decade.
Topics are here:
- Temperature development of the battery during charging
- Temperature development of the battery at different driving cycles and environmental conditions
- Heat generation by the flow of current
- Electrochemistry in the cells
- Cooling of the cells
- Tightness of the housing
- Pressure tests
- Behavior in case of crash
- Thermomechanical behaviour
- Thermal Shock
- Short-term and long-term behavior of mechatronic components
- Support necessary tests for material characterization
We use both FEM and CFD tools, depending on the question on which the simulation is based.
Are you involved in the development of new electric vehicles or electric motors, fuel cells, battery housings, battery cells, controls or other components and have to ensure that the requirements are met? Here you can benefit from our longstanding and unique know-how.
Arrange a non-binding appointment, gladly also via video. We will be happy to inform you how you can keep up with the disruptive changes in automotive engineering with us as your simulation partner.
Your Stefan Merkle
PS: Do not miss my blog on the current assessment of the situation in the automotive industry next week.