I was stopping by a grocery store in a busy shopping center. Prior to reaching the shopping center, I was getting excellent MPG - hitting around 38. The shopping center was extremely busy, with no parking spot in sight, so I had to do some circling. At first the car was running in battery mode, a few minutes later, I noticed the ICE turned on (battery indicator showed around 1/4 left), and the analog needle hovered around 0 mpg... Just a couple minutes of this, my previously achieved 38 mpg was gone, it went below 25 that the dashboard lights all dimmed...

So here's the question, is there a "threshold" that the battery hits for the ICE to kick on? It felt like the ICE turned on to charge the battery just a little...

 

That's precisely what it does. The system is designed to keep the battery in a state of charge that is well inside of the minimum and maximum capacity. This promotes longer battery life.

 

If you have the non-NAV system and are just looking at the dash monitor it is indeed difficult sometimes to tell if the ICE is off unless you look at the instant FE gage. If it's reading "0" the ICE is running. If it's on "E" it's off. The ice is really quiet at idle. The NAV system shows a little more information on the ENERGY screen.

I can't imagine going from 38 to 25 unless you had just reset the trip gage and was monitoring the trip mpg with a short trip. I have not noticed a great impact when the ICE temporarily kicks on as I'm driving on battery, it usually does not stay on long. Then again I'm not a professional shopper and don't know how long you were cruising for a spot.

 

I do not notice any alternator (per say) on this engine and the A/C compesor is also run by electricity, when the ICE starts to charge the battery does the electric motor turn into a generator??? as it is coupled to the ICE. sk

 

I had a weird thing happen the other day. Went to lunch at work and got stuck in some road construction.

I was delayed for quit a while (about 12 minutes) and hardly moved at all during this time. I was watching the Nav system and noticed that my consumption went from 31.7mpg down to 16.1mpg!

Even though it was a warm day and I had the AC on, the ICE was only idling for probably less then 8 minutes and the battery reading was high (blue with all but 2 bars) so there is no way the vehicle could have consumed this much fuel?

By the end of my commute home the reading had come back up to 31mpg.

Strange.

 

I wonder if the TCH, when sitting still in traffic, is registering 0 MPG (or so close to it) that causes the computer to have a false or upside down sense of true mileage? This could possibly be the reason that the average MPG might come way down.

I've noticed that on the NAV consumption page, when there's a particular minute that I've been moving for a very short portion of that minute and sitting still for the greatest part, that the MPG shows all the way up to 60 MPG. But when I'm sitting still for the whole of a particular minute the consumption gauge does not register any part of a yellow bar, possibly registering 0 MPG.

 

Had you just reset your MPG on the nav system?

If so, this is understandable. It's all about the math - the average is very sensitive to the number of miles traveled. If you travel a very short distance, and you use gas while idling in traffic, your average MPG will suffer. This isn't as sensitive when you have 300 miles traveled...

 

The synergy drive has both a generator and at least one electric motor(4wd has a second motor). Here's a link from Toyota of Japan explaining the synergy drive:

http://www.toyota.co.jp/en/tech/envi...hsd/index.html

 

No. I watched it as it was counting down.

 

Thanks for the info, i see on the diagram, engine- with generator between engine and electric motor. SK