Mountain Driving Strategy

welcome and congrats!
i would use ev auto, and force charge when on areas of lower inclination.

 

Based on my experience on smaller hills, it looks like the Prime will sustain battery charge on hills. Since the descent into Silverthorne is steep and long, I'd use Ev enough to drain the range below 10 miles so you have enough room for the long regeneration. I'd do this on the flats, probably, the last bit in the tunnel, if necessary. Then I'd do the climb up I-70 in Hv.

Like I said, I haven't done this climb yet, just Monument which is a little bump by comparison.

 

This particular downhill section is kind of remarkable. It's 7 miles of 7% grade at 60mph, with no breaks.

80% is the max from Charge Mode, not "full charge".

 

I just came back from Yosemite and did a couple of two hour drives. 308 feet to 5000 ft. Back and forth from Fresno. I did try the charge function but believe it or not, the Prime charged itself on the downhill leg, and I discovered I didn't burn off enough EV miles. In other words I reached the max charge it would do with regeneration. The rest was just wasted. This car is amazing.

I used the electric portion in the Valley, and I played with how much I'd leave for getting around town to the hotel.

 

I use EV to get me to the freeway. Hv on the freeway and up the mountain, then EV down the mountain. I went 85 miles on 21 miles of EV range once that way. Once the road levels out, go back to Hv.

I always plan the end of the trip with an EV range of 0 left.

Reno, NV to Folsom, CA, 125 miles, 141mpg.

 

Just a geography note here. Reno (4,505 ft elevation) to Folsom (220 ft) is one big long downhill run out of the Sierras, with a bump to go over Donner Pass (7,056 ft) . I doubt you would get 141mpg in the other direction.

 

Funny you should say that. I did exactly that today. You are indeed correct. I worked hard drafting a fast semi and barely got 65 mpg. The mountain makes a big difference.

 

Downhill makes a mountain of difference.

 

As a nerdy engineer with a decent knowledge of the system's operation, here's my "general advice" to use for any situation. There are exceptions, but I think it covers what most people are looking for. I write this to help folks with differing situations, but it applies to this one as well. It jibes with @Prime8 and @Tideland Prius.

1. Always charge the car up before departing. If your trip starts with downhill driving, leave the hybrid battery empty enough so that it'll never fill up on the drive. You never want to waste the possibility of regenerating energy.
   
2. Look at your route and decide if can all be done electrically.
   1. If yes, choose EV Mode and you're done!
   2. If yes, but you like extra power (engine will come on with lower power demand than EV Mode), choose EV Auto.
      
   3. If not and you are lazy, choose EV Auto and let the car do its thing.
      
   4. If not and you like pressing buttons or hypermiling, analyze your route (proceed to next step).
3. Consider the portions that are stop/go or slow speed. Make sure that when you get to them, you have enough hybrid battery to get through them with little to no engine use. When you get to them, use EV or EV Auto.
4. Consider the downhills. Make sure when you get to them that you have used enough hybrid battery that regenerative braking won't fill the hybrid battery up completely.
   
5. Consider the hills. If long/steep, enable HV on these portions even if you have hybrid battery available.*
   
6. Consider the straight sections. If high speed or moderate speed with headwind, enable HV on these portions even if you have hybrid battery available.*
7. I would not force charge the hybrid battery with the engine.**
8. If you end your trip with hybrid battery capacity left and you can charge at your location, you should have used more battery during the trip.

As for Eco, Normal, Power: choose Eco for best energy economy, Power for more responsiveness, or Normal for a middle ground. Those are more about feel of the car/pedal than direct energy economy (although Eco reduces energy usage from climate settings and might encourage you to drive in a more efficient manner).

*If it's near the end of your trip and you have enough battery left to reach your destination and you can charge at your destination, use EV or EV Auto and use up the hybrid battery.
**Unless you're on a camp-out with a depleted hybrid battery and not enough gasoline to get to civilization and need some power to charge your cell phone to make an emergency call (if you have cell service). Otherwise, let the hybrid system determine what's best: in all likelihood a long hill has some level sections where it'd make sense to turn off the engine temporarily, which Charge Mode wouldn't allow. Also, in Charge Mode you run the risk of charging up the battery to a point where you'd run out of storage capacity during regeneration on a downhill. I sure it's possible to force charge at proper times for ultimate efficiency, but it's probably too complicated for most people.

 

I concur.

As a side note, beware of B mode. It forces the engine on in circumstances where EV would be preferred. Don't use B mode after the EV portion of the battery has been depleted. It will keep the engine running at stoplights.

I run past the EV portion of the battery more, now that I know how to keep it in EV mode after the EV portion has been exhausted. I get an extra 1-3 miles of EV past that point now.

 

lol, good one! (@Prime8, primate)

 

The whole point of B mode is to keep you from destroying your brakes on long downhill stretches. So definitely use it when necessary. If you have battery capacity left to fill, use it in Ev. If you don't or if the battery won't take the charge, use engine braking. Prius has small brakes which will easily overheat and fade if you don't do this on a big hill.

 

FYI
I will have racked up 15,000 miles in my first five Prime months and have some observations: (All anecdotal, since I am enjoying my new blue streaker too much to concentrate on rigorous data gathering)
1. I may be over-analyzing, but I think that keeping some EV range "in the tank" (not using up all the allocated traction energy) seems to give HV mode some extra breathing room for some of the more energy draining longer segments on my typical trips. The computer appears to be more willing to "dip deeper" into the EV portion of the traction battery energy in HV mode than into the smaller portion specifically set aside for that purpose. And eventually, the computer does get around to replenishing that energy.
2. Using the "CHG" and "EV Mode" alternately seems to produce substantial MPG results, but "HV Mode" seems to produce results that are almost as good, and requires less operator attention to achieve them. ( I am not a card-carrying hyper-miler.)
3. Always plug in whenever possible (especially at one of the currently numerous free charging stations.) You never know when a "short local errand" will turn into a longer excursion, causing you to begin "drawing down" some of that more expensive fossil fuel energy.
4. Utilize the ECO hints that the car display provides. They will help you to stretch your store of energy to the max.
I have been stable at one location for over two weeks now, and have only used 3 miles worth of petrol in 550 miles of local driving. Temperatures are now dipping into the below freezing zone here in MD, and my ICE is coming to life when I start out in the morning, even though I have a full charge accumulated overnight. My guess is that the electronics cooling system is too cold and needs the ICE to warm up its coolant. The ICE has shut off within the first mile or so of a (brrrr.... cold) morning drive.
There. That's my two cents worth.... so far.

 

Here ya goh @bisco another candidate