65 Mph On Electric Engines

[rocky2]

Just thought I would share with you an interesting experience I had last week.

We were very late to dropping someone off for a flight in Chicago. When we realized our gas tank was almost empty it was too late. We had to keep going and take the chance of running out. The gauge said empty.

On the way there the hybrid display said we were on electric only, 99 MPG pegged, and 65 mph. It stayed that way for approximately 3 minutes.

I saw something I never saw before. The bars that show the charge on the battery were lit green, with the top two bars filled in for the first time ever. I have never seen the top two bars filled in, or all the bars green.

We made it to the gas station just after we left the airport on the way back. Based on how much fuel the vehicle had ½ gallon of fuel left.

After we fueled up the car acted like it normally does.

Don't know why the vehicle charged up so much. Maybe because of low fuel? Don't know why it ran at 65 mph on electric only.

Also, we generally get best mileage above 60 degrees. Usually around 26 / 27 mpg (85% city / 15% Hwy). However for every 10 degrees drop in temp we loose 1 mpg. Don't know why.

[thesaintjim]

wow, nice. It has been so cold here in PA that my gas mileage has dropped to 24mpg from 29mpg. I'd be scared to death on running it on 1/2 gallon :)

[JasonATL]

It sounds like you were on a downhill stretch on cruise control. 3 minutes sounds like a really long downhill stretch. I have a mile or two downhill (not steep, just nice and smooth slight downhil) stretch on my daily commute. When on cruise at about 65 MPH, there is no indication that the ICE is on and the electric motors will kick in intermittenly to maintain the speed. It is also possible that you had the wind at your back to cut down on your drag -- or you were drafting behind a semi?

I doubt that it had anything to do with the fuel left. In fact, on the assumption that the 400h obeys the laws of physics (it can't create energy from nothing), it would have had to burn more fuel in order to charge the battery beyond the norm. You said you were in a hurry. So, when you started out, you might have accelerated quickly and then didn't use the electric motors at low speeds. Your normal breaking would have recharged the battery. Going home would have appeared normal, since you would have (assuming this scenario is accurate) been going back uphill or driving otherwise as you normally would (since you weren't in a hurry).

[patt]

The bars go green whenever the battery charge is high (top bar or second from the top bar are on). I think it is just so you can see in a quick glance that the charge is high.

In my experience, one of two things makes the charge level get that high - the beginning of a drive in cold weather or a long downhill stretch.

When you start out in cold weather, the system will run the engine to get it warmed up to provide cabin heat even if the conditions would otherwise allow it to run on the stored charge. In that condition I have seen it go to all but one bar charged but I live in Northern California. In a colder area like Chicago, maybe that continues long enough that it gets all the bars lit. Also, if it is really cold I usually turn on the seat heater until the cabin temperature comes up a bit so maybe that ends up drawing enough to keep the top bar from getting lit.

On a long downhill, the regenerative braking also charges the battery and can get to the all green.

It doesn't take much of a slope to allow the car to go all electric at 65. It can be just barely noticable. It is also possible that the system takes the high charge level into account - the battery is charged above the target charge level so it is better to take power from the battery for a bit as long as it can get enough without overworking the motor.

Going home, your car was already warmed up and you probably took some charge down on the airport access roads. Also, if you were downhill or wind at your back on the way to the airport you probably had the opposite on the return journey so the engine power would be needed.

[rocky2]

The trip from my house to Ohare airport on the tollway is on a perfectly flat road. The wind was calm.

I have driven on flat midwest roads at 75 mph for several hours and never saw the bars go into the last two

bars and turn green. I wasn't using my brakes. We were not in the car more than 30 minutes when this happened. Oh well, who knows. Hasn't happended since.

I would not have likely even noticed what happened except we were very low on gas an I was paying attention to the instruments.

[patt]

When the bars go green because of the engine running to warm up the car, that happens right at the beginning of the drive - first five minutes or so at Northern California temperatures. It isn't high speed driving that does it - it is running on engine to get the engine heated enough to produce heating for the interior when otherwise it wouldn't need to run so it is creating extra charge to store in the battery.

At 75 miles per hour, I've never seen the batteries go high and except on a very steep down hill, I haven't seen it run on battery. The air resistance at that speed needs plenty of power to keep up the speed.

The trip from my house to Ohare airport on the tollway is on a perfectly flat road. The wind was calm.

I have driven on flat midwest roads at 75 mph for several hours and never saw the bars go into the last two

bars and turn green. I wasn't using my brakes. We were not in the car more than 30 minutes when this happened. Oh well, who knows. Hasn't happended since.

I would not have likely even noticed what happened except we were very low on gas an I was paying attention to the instruments.