Plug-In Prius: real winter driving

Yes.

It was a very "cool" drive.

Note that I did briefly fire up the heater at 65 while the engine was warming up. But then shut it off as soon it reached tolerance. Hopefully, that was mostly just waste heat I was taking advantage of. Following that, you can see it slip into EV repeatedly while driving in HV.

 

It's been awhile. I still have some videos to edit & share from when it was really, really cold. But I did manage to finish this one from just the other day done...

9°F outside this morning meant an opportunity to try out single-camera filming again. The sun was rising quickly; that meant I'd be pushing exposure limits with the contrast between dashboard scenery. I really wanted another example showing what happens while you "Just Drive It". The battery had finished recharging 6 hours earlier. The engine hadn’t been used for about 10 hours. The garage temperature was around freezing. I pulled out, adjusted the camera, hit record, then drove away. After traveling about a block, I turned on the heater. It was set to 70°F with the blower on 2 bars.

The request for heat caused the engine to start. Still being in EV mode (the default), I was looked forward to it shutting back off as soon as the warm-up cycle completed. That happens when the coolant reaches at least 145°F and there isn't demand for high power. The engine will then remain off until the coolant drops to 136°F. Note that lower the heater temperature also lowers the coolant threshold.

As I drove, the engine starts up, runs shortly, then automatically shuts back off. That's why I call that a "heater dance". That same cycle repeats over and over again, until the battery is finally deplete of EV capacity. Following that, the same things happens in HV mode but with less electric-only power. The purpose of the plug is to boost MPG. So even when the engine runs, the system is still taking advantage of plug-supplied electricity. EV driving is not necessary for great efficiency. This video clearly demonstrates that.

17.9 miles was the total distance traveled. 85 MPG was the result, with 1.3 miles of EV capacity still remaining.

 

I managed to capture one more drive with snow still on the ground...

Just like the other suburb drives I've filmed, this one takes me to that distant coffeeshop. The run back & forth is a good basis for demonstrating what happens as the EV capacity is utilized, then what happens after it's gone... which is why I filmed that same route prior to getting the plug-in model. You can clearly see the benefit.

This footage featuring that rare lighting circumstance when a single camera can be used. Too early or too late, there will be over & under exposure. The refresh of the screen will become an annoying flicker as well. In this case, I took advantage of the sun setting with the horizon obscured by clouds. It provided a nice balance between dashboard and scenery, as well as show a nice pink in the final moments before the sun disappeared.

As for the drive itself, shown at 5X normal speed, you can see me pull out into traffic driving in just EV. But with a route longer the total capacity available, I fired up the engine right away. That resulted in a boosted MPG until warm-up is complete, then the engine shuts off. Watch the estimated EV distance value. I suddenly drops from 9.6 to 8.5 when I turn on the heater to blow air on the windshield to keep it clear for the filming. Capacity itself is unchanged. That's simply how you are informed of the potential EV loss the heater could cause.

Driving was uneventful, the usual stoplights & stopsigns you'd encounter driving through the suburbs. When accelerating hard, the engine will come on to help provide power. Watching the MPG, you can see that doesn't actually lower MPG much and it shuts off relatively quick afterward. In the summer, it shuts off even faster. But at 28°F outside, it runs longer.

Halfway through my drive back, you can see me approach a long hill. Climbing that with only 1.8 miles of EV remaining wouldn't be the best use for that electricity. So, I switched over to HV mode by pushing the button for that on the dashboard. When at the top, I pushed it again to switch back to EV mode. That feature comes in handy when you want to preserve electricity for use later.

At the conclusion of the drive, the overall result was 135 MPG for the 15.7 mile round-trip. The entire EV capacity was consumed; that's roughly 3 kWh of electricity including charging losses.

That was a great drive for winter, but I sure miss summer. In warmer temperatures, resistance with the battery itself is lower. That more efficient transfer of electricity allows you to drive further EV from each recharge. So whether you use gas or electricity, cold weather reduces efficiency.