The automotive industry is placing high importance on technologies that can reduce CO2, even in a highly fuel-efficient compact car. One major technology is Stop & Start(S&S) System, with a combined energy regeneration system.
A key component of the system is a power supply storage device that has high-charge acceptance, light weight, and compact size. We believe a Lithium-ion (Li-ion) battery completely meets these requirements.
For the battery, there are three key points:
- 1
Battery cell specification
- 2
State Of Charge (SOC) detection method
- 3
Temperature management for Li-ion battery.
We have already proposed the battery cell and the SOC detection during SAE 2013, and now we are going to introduce “Temperature Management”.
If the temperature of a Li-ion battery operates over 60 degrees Celsius, the battery could be severely damaged. Therefore, temperature management of the battery is very important.
Conventionally, the temperature is managed by several thermistors and a cooling fan. However, this method is difficult to install in a compact car where cost and space are limited.
We have developed our battery pack with the flexibility that allows it to be put in a compact car. The pack has two features:
- 1
One thermistor measures the temperature of one of the cells, and then the temperature of all the cells is calculated using a secondary temperature off of the control board.
- 2
The temperature of the battery is controlled by natural cooling.
We succeeded to install this system in a compact car through our new temperature management.