Thermal Management of Battery Electric Vehicles -BEVs

Battery electric vehicles (BEVs) have seen rapid growth in recent years. However, lithium-ion batteries are prone to thermal fluctuations, and at cold temperatures in particular, their performance and capacity decline temporarily. BEVs do not have an engine-based heat source. As a result, it is necessary to collect heat generated by nearby components such as motors and inverters in order to extend the driving range. 
Heat movements can be visualized by measuring heat flow. This approach makes it possible to implement effective heat countermeasures since it can determine if a certain measurement target generates heat or receives heat from nearby components. Furthermore, knowing which components generate heat allows for more efficient insulation and heat dissipation designs.
Heat flow can be measured by combining the MEMORY HiLOGGER LR8450 with the FHF05 Heat Flux Sensor. They are useful when validating thermal management because these sensors can confirm both temperature and heat movement direction.
Figure 1 shows a screen capture of the LR8450 and FHF05 used to measure temperature and heat flow for a component in a vehicle while it's being driven. Whereas temperature continues to increase gradually, the heat flow graph changes from positive to negative when the vehicle is stopped. In other words, it's possible to confirm that the component generated heat while driving and then received heat from surrounding components when the vehicle was stopped.
Heat flow measurement application
Battery performance and rate of degradation are correlated with heat generation. The ability to measure heat flow in batteries is expected to facilitate performance evaluation and non-destructive degradation diagnostics.
Measurement method
Connect the heat flow and temperature wires of the FHF05 to the measurement channels of the measurement unit for LR8450. The FHF05 can simultaneously measure heat flow and temperature with a single device.
To read the heat flow rate directly, simply input the sensitivity coefficient (S) noted on the FHF05’s cable into the LR8450’s scaling sensitivity field. There’s no need for time-consuming scaling calculations.
You can set upper and lower limit values on the waveform screen as desired and observe the waveforms. The ability to display two axes at the same time is extremely convenient when you wish to observe temperature and heat flow simultaneously. 
Advantages of heat flow measurement with the LR8450
The wireless unit connected to a heat flow sensor can be placed near the measurement target, and you can observe variations in real time from a separate location. Communications range: 30 m, line of sight
(The communications range may be shortened if you place the LR8450-01 or wireless unit on the floor or ground.)
The sensitivity of heat flow sensors is temperature dependent. High-precision heat flow measurement is possible by using temperature measured values to perform temperature correction with the LR8450’s waveform calculation function.

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