I have been trying to figure out exactly what does it mean when I have a symbol of 1/2 a car, an entire car, or sometimes a car and a half on the mpg screen.

 

Car???

Can you post a picture?

Edit: I just noticed that you have NAV. and that your question must be about it. No idea here as I have just the std MFD in the dash.

 

 

I'm not an expert but its the amount of electricity regenerated from the brakes. More braking = more electricity generated and sent to the battery.

 

A full car symbol on the display is 50 watt-hours of regenerated power, and a half car is 25 WH. A watt is a volt times an amp. Crudely speaking, the faster your generator is turning (a function of wheel speed and engine speed and whether MG1 or MG2 or both are doing regeneration), the higher the voltage. The harder the deceleration (harder braking/faster slowing) the higher the current (amperage). The longer time you decelerate, the greater fraction of an hour. Multiply the voltage times the current (measured in amps) to get watts, and multiply that times the length of time (measured in hours), and you get watt-hours (WH).

(Less crudely speaking, the electrical controller for MG1/MG2 controls the voltage, which controls the motor power or generator current. When the controller sets the voltage lower than the open circuit voltage of the MG, it generates current and tries to slow down, proportional to the voltage difference. The open circuit voltage of the MG is directly proportional to the speed of the MG.)

Off the top of my head, I believe the TCH drive battery is 236 V total, with each cell rated at around 10 amp-hour, which would be a 2360 watt-hour battery. However, only about half of the total capacity is actually used to ensure very long life for the battery. That means about 23 of those car symbols on the consumption display would represent a complete recharge of the drive battery (23 cars X 50 WH = 1150 WH, which is about half the total battery capacity).

-- Alan

 

yeah....what alan said....lol....

 

Thanks Alan.

 

The technical description is a few posts above.

It simply shows how much energy you have put back in the battery when you brake.

For best mileage you don't want to have any "cars".

Charging the battery isn't 100% efficient. Neither is using energy from the battery.

Kind of like taking a dollar, going to a currency exchange, exchange the dollar for a Euro, then taking that Euro and exchanging it back for a dollar. You end up with less than you came in with!

To maximize mileage you want to minimize use of the brakes (and the accelerator!). To do this you need to anticipate traffic and lights.

 

Thanks for the practical explanation. So to follow up, if the regen. from the brakes is bad, then is the regen. from the ICE better (more efficient)? The battery has to charge from somewhere.

 

It isn't "regen" from the "brakes." The regenerative breaking is the electric motor slowing the car instead of the brake pads. If you were to do it right you could slow to about 6 mph before using the brake pads. (6 mph and below always use the brakes pads.) To do this you lightly press on the brake pedal.