Cold Weather and a Hybrid

One thing about the IMA Honda hybrid, the electric assist can be viewed as a powerful starter motor (10kva -> 14 hp). That starter motor is used normally to assist the 1 liter gas motor when needed and also to “instantly” start the engine when the gas engine is shut down while braking and the speed drops below 18mph. When the system is put back in gear the big NIMH battery pack and the 14hp starter spin the engine up astonishingly fast.

In cold weather, tomorrow Chicago forecast is for -9 F and Thursday morning -16 F is expected. That big battery and big starter motor work a lot better than the more standard starter/9v battery.

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  1. Boonton says:

    I’d be curious to know how the car functions in cold weather. With such a small engine how does the internal heat work? Does it take a long time to get warm inside or is it fast?

  2. Mark says:

    It certainly doesn’t warm up as fast as other cars I’ve been in. The internal heat works like most/many other cars, getting heat off the engine. The engine itself today took about 4-5 miles to warm up. The shocks were a little stiff until things warmed up.

    Also, the engine block is aluminum, which means when you turn it off, it cools off very fast. But aluminum also ha a low heat capacity so it heats back up fast too.

  3. Boonton says:

    So the car is always burning gas no matter what. The hybrid aspect just lowers the rate of gas consumption. I was wondering how a car that sometimes goes totally without combustion would manage to provide internal heat in really cold temps without killing the battery.

  4. Mark says:

    Not quite no matter what, it shuts the motor off when stopped or coasting at slow speeds. Some people have installed a “shut-off” trigger switch so they can cut the engine when coasting down hills at highway speeds. The other reasons why the engine would not cut off when stopped include, the ending isn’t warm yet, the heater is on too high, the AC is running, or the hydraulic pressure is low. The steering assist is electro-mechanical to avoid needing hydraulic pressure (used only for brakes) and let the engine cut off more in city driving conditions.

    The Prius is more of a “full” hybrid in that can run at up to 30mph on only battery. The Honda IMA system never drives the car forward without the battery. The assist lets them get by with a smaller engine and lower gas consumption. They also played with the the fuel injection system to let the engine run a lot leaner than an ordinary motor to assist getting high mileage. As I’ve noted before, I’ve driven to Atlanta (730 miles) averaging just under 80mpg. I’ve gotten as high as 94 for shorter drives. But … cold weather cuts into that. Today for example, I “only” got 56 mpg driving 100 miles on the highway. It it was 70 degrees out instead of -10 that would be well above 70mpg.