It looks like all NIMH hybrid Toyotas are experience the same issues with battery temperatures, especially when driving downhill and regenerating. I drive a 2020 ES 300h With NiMH battery And it is doing the same, especially during summer months. When the battery temperature goes above 45 C, the WOUT from the battery is almost 0. That is when ICE runs all the time. The problem is that the cooling fan comes on when the battery temperature is 38 C or higher and in my opinion it should go to full blast before it reaches 45 C. I would like to change its settings, but it seems like there is no possibility. Sometimes I use Dr. Prius to manually adjust the fan speed. My idea was to install a CPU fan (8 cm) before the battery cooling fan so it would work all the time in full blast. any ideas?
maybe you can find the right pins on the connector that would keep it at full speed when the car is ready.
The temperature sensors read temperature and communicate this to the ecu. My solution is to get the same thermistors and connect in parallel two thermistors. This will register higher temperatures to almost double. This will tell the ecu that the battery is hotter than it is so it will start the fan earlier. This applies to hot climates only. Do not do this if otherwise.
