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FAQS

HOW TO ENGINEER A BETTER BATTERY SYSTEM FOR OFF-HIGHWAY VEHICLES?

  • Focus 1 - The term “cycle life” generally refers to the number of complete charge and discharge cycles before the battery’s capacity degrades down to a certain percentage of the original starting capacity.

  • Focus 2 - Thermal Cooling is one of the most critical features and considerations when designing battery systems for electric vehicles. The battery cells only have a narrow window of operating temperature for optimal performance. Fast charge under low temperature could lead to lithium plating, while operating at high temperatures could lead to the rapid build-up of solid-electrolyte interphase -  all of which would have a negative impact on the battery life. This could also have severe safety implications.

MAJOR DIFFERENCE BETWEEN A PASSENGER BATTERY ELECTRIC VEHICLE (“BEV”) AND AN ELECTRIC OFF-HIGHWAY VEHICLE ("EOHV")?

Most passenger BEVs experience a full charge and discharge cycle once every few days, whereas an EOHV might experience more than one charge and discharge cycle per day.

 

In fact, most EOHV are operational 24/7 (including charging/refueling), with 2 to 3 operator shifts during a full 24-hour day.  Most passenger vehicles are only operational for 1~3 hours per day while parked unused for the rest of the day.

 

BEVs are charged at home or at work with slow charging (overnight or over an 8-hour workday), whereas EOHV generally require on-site fast charging, thus reducing the amount of service downtime.

The constant usage of the battery system in an electric off-highway vehicle puts huge pressures and stresses onto the battery cells, thereby requiring them to possess higher cycle life capabilities

WHY DO I SELECT IMMERSION COOLING?

With immersion cooling, the battery cells are directly immersed in a non-conductive, non-flammable, and non-toxic fluid with a dynamic flow rate across the system.
This approach ensures that the temperatures are uniform across the cell, all cells, and the fluid, and suppresses any thermal runaway events that could occur.

WHAT HAPPENS IN THE EVENT OF THERMAL RUNAWAY SITUATION?

In a typical non-immersion cooling system' s thermal runaway situation, gases will be generated and vented when the pressure-temperature current (PTC) switch on the lithium-ion battery cell opens.

The released gases consist of water, carbon dioxide, carbon monoxide, hydrogen fluoride (HF), and some light combustible hydrocarbons (methane and ethane). In non-immersion cooled settings, the heat generated during thermal runaway events will pose a risk to further propagation of the remaining cells.

For the immersion liquid cooling method, the coolant will absorb the heat more effectively and prevent thermal propagation. A lower temperature will also prevent gases reaching flash points, which also prevent further thermal propagation. In either case, the amount of light hydrocarbon would also exist in trace amounts as well. 

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