Y'all, Here's a stumper for the Prius community. Most of the time, when the Prius engine is running, some combination of arrows are illuminated on the MFD Energy display. For example, arrows are lit from the ICE to the wheels when the car is running on the ICE. Arrows are lit from the ICE to the battery when the ICE is charging the HD battery, etc. Sometimes, when the car is stopped (such as at a traffic light), and the CVT is in "D" mode, the ICE will run to charge the HD battery, and arrows are lit from the ICE to the battery. At this time, these are the only arrows lit, as the car is not moving. Other times, when stopped in the same scenario, the ICE will be running, but no arrows are lit. In this case, what is happening? Where is the energy going? Just curious. I can't find any mention of this in the Owner's guide. TIA, Glenn
The ICE is idleing and the energy is being used to warm the engine and cat. I assume the PSD is essentially in 'neutral' during those conditions.
It's a very good question. There is no neutral in the PSD. If the engine is turning and the vehicle is not moving, then MG1 is turning. Perhaps, however, there is no load on it. There would then be no power transfer. Another possibility is that the MFD is wrong. I have occasionally noticed anomalous displays which I suspected were wrong. Note that the MFD only shows one motor/generation, and is therefore a simplification of what's actually going on.
MG2 stopped, yes car not moving, MG1 not moving, no, ICE running and driving the planet carrier in the psd, yes, and in that case no charge to the battery and the ICE warming up the cat's and the coolant. Yes. Most likley senario is that MG1 isn't charging and is turing. Just my thoughs.
The Multi-Display simplifies energy-flow quite a bit. There is obviously some numeric rounding at play to prevent the arrows from switching too much. And of course, there are some tolerances with the electricity itself. So "no load" is likely a little tiny bit, but so small that it isn't actually used.
I often get the no energy transfer (with 99.9 mpg continuous) on a very slight down hill. I have a number of these on my daily commute. This is a very slight down hill. I generally am in cruse control. Between 35 and 45 mph. The display shows no transfer. I have turned off the stereo ( no tunes help!!! :guns: It was in the interest in science only) and I can not feel or hear the ICE.
If the ICE is not turning and there are no arrows, but the car is moving, then you are coasting. MG2 is turning, because it's connected directly to the wheels, and MG1 is turning, in order for the engine to be stationary. But with no load on either MG and the ICE off, there is no flow of power. Eventually the car would slow to a stop unless at some point some power is applied, either from the engine or from the battery. This situation is generally called "dead-banding." It's more efficient than coasting in a conventional car, because the engine is burning no gas.
