I am eagerly anticipating, the next chapter in this awesome novella.
Chapter Five: the Exceptions
In the previous chapter, I discussed the all-important pulse-and-glide technique for city driving, and explained why you should actually avoid driving the Prius on all-electric mode (yellow arrows running left-to-right on your Energy Monitor, as shown below) in order to boost your average mileage in the long-run. Odd, but true: relying solely on the battery to power the Prius will decrease mileage in the long run, as the gas engine will be required to re-charge the battery. It’s so enticing, driving the Prius, with the gas engine off, silently. There are even after-market modification kits available that allow you to override the factory settings and drive in full electric vehicle (EV) mode at speeds of up to 34 miles per hour. But, in the end, you’ll be better off if you resist this temptation.¹
Mostly. As with any good rule, there are exceptions: in this case, situations in which it is advantageous to “run the yellow”.
So go ahead and drain your battery in EV mode when…
1) You are maneuvering in or out of parking lots, garages, driveways, etc., at low speeds. The EV hack is particularly useful here, as you cannot do this at start-up without it.
2) You are about to hit a long stretch of downhill road; once you get there, lay off the gas on the descent, and let gravity recharge your batteries (technically, let gravity pull your car downhill, and let the regenerative braking system convert kinetic energy into battery charge, but you get the point).
3) You are about to get on the highway. At highway speeds (above 41 miles per hour), the Prius’ gasoline engine will always be on, even if it’s not needed to propel the car. The engine is programmed that way so that it is instantly available in case you need for sudden acceleration. At lower highway speeds, such as the recommended 55 miles per hour), the engine not only propels the car, but also charges the battery — you will notice after a few steady minutes at 55 that the battery stays at around 80% full. It really doesn’t matter whether the battery was 20% full or 50% full when you got on the highway.
4) You are about to arrive at your destination. It won’t matter what the battery’s state of charge is when you turn the car back on hours later, as the engine is going start in its “warm up” stage by default, recharging the battery in the process.
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¹ Damn you, temptations! Why must you be so tempting???
Responses
By: DAVID J CARTENUTO on January 20, 2008
at 10:30 am
