I wish Lexus would publish some information as how the Hybrid computer works and what parameters and logic it uses to turn on and off the engine. Recently, as I approach a stop light to stop, the engine shuts off and after I stop 5 seconds later it starts although the battery shows it is full!

 

If the battery was really full, I think the only thing that should restart the motor is if it were cold outside and it needed engine warmth to heat the cabin.

What was the outdoor temp?

 

Our 500h NEVER shows full, on the multimedia screen (vehicle>energy monitor)

Always seems to have one battery-charge segment to go.

Never shows depleted, either. But just driving at slow speeds (as, in a parking lot looking for a space) the charge will drop.

 

The temperature was around 65 degrees. The AC/ Heater was off. The headlights were on. The battery was definitely full. I know most of the time the battery level never shows full and is down one segment but it was full this time.

 

Sqorry, I did not mean full. Full is the mid range or a bit over half way. It should never show full or completely empty.

 

Like the poster said, above. It should never show full. Lexus programming keeps it in the middle plus or minus a couple in each direction.

 

I will take a picture of it when it is full and post it. I agree with you that the battery never should be full but it is happening. Keep your left screen on the battery level and you might see it getting to full when coasting down hill.

 

Hello, Please see attached pictures that shows the battery level not full and then full. (350h).

 

If it concerns you, take it to the dealer so they can tell you that all is OK.

 

The fact it shows full on the screen doesn't mean that the battery is at 100% charge, in the same way as no bars doesn't mean that it's fully depleted. The system is designed to operate within certain parameters in order to maximise battery life, and so the full and empty levels shown on the screen are for pratcticaal purposes, rather an exact state of charge. At least that's how it was explained to me.

How that applies to your engine cutting in when the battery eppears full, I don't know. I would imagine though that the engine runs for a variety of reasons other than just battery charging, such as maintaining engine temperature, for example.

 

Not a direct answer to the question, but a very interesting video on start/stop considerations:

 

Hello,
Thank you all for your responses. And thank you RolfK for the video. That video in the section "Start Stop Computer Logic" did explain what I needed to know.
I appreciate it.