I want to run some tests to determine which strategy yields the best overall MPG, using EV for climbing hills and HV for cruising, or vice versa. The problem is that once I start performing the initial thought experiments I end up with too many variables that could turn the tide either way depending on the design of the test. I'm thinking the simplest test to start with is a route with some hills and some flat areas where I can make a run both ways using each strategy and see which comes out on top. Does anyone else have any ideas for a rigorous test to determine which strategy is more fuel-efficient overall?
EV boost for hills, use em both. Leave it in EV and go into power to get help from ICE. Too many variables. Engine warm or cold, distance to travel, can you recoup EV after the climb, etc.
It depends on your route and how you want to use/ration your EV miles. I have tried using EV-BOOST on highway driving and it lowered my EV range estimate to about 11 miles. If you want longer EV range (for more miles ahead before the next recharge), switch to HV mode earlier. I think the answer depends on each individual route and you may have to play with yours to find the optimal technique. For me, I use EV miles mainly for the city. I switch to HV mode when I need to merge onto highway for longer trips. If I need to take highway for short trips, I just stay in EV mode.
Okay, this is silly. The EV range is just some number. Using EV-boost doesn't somehow magically reduce your actual EV range. We've been over this many times The main thing about EV is that if you can charge at your destination, you should never conserve EV miles. I drove 18 miles in mixed city/highway driving, never left EV mode, and still had 3.2 miles left when I arrived. If I had switched to HV mode, I would have gotten lower mpg and had even more battery remaining. Why?
If your ultimate goal is to pollute less, and assuming your electricity source is less polluting than burning gas, the real question is which motor is more efficient at providing torque to climb hills. If I can HV up a theoretical hill for 12 miles on one gallon of gas and then travel 12 miles of flat using EV mode, I've traveled 24 miles on 1 gallon of fuel. If I use EV for the first 6 miles of hill, 1/2 gallon of gas for the next 6 miles, and then cruise 12 more miles on another 1/4 gallon, I've used 3/4 of a gallon.
But, in most cases, the EV fuel is not zero pollution. So if the electricity pollutes about 1/3 as much per mile you can add that in to your calculations. (1/3 is probably a good approximation...EV mode is about twice as efficient in terms of turning a unit of energy into a mile on the wheels as the Prius ICE. And, generally, some percentage of electricity, nation wide comes from hydro or nuclear, which are the only major sources of electricity with no significant air pollution or CO2. (yes, we have some small percentage from wind, solar, geothermal, but not enough for this approximation). Also, I'm not sure your numbers make sense. You make the HV uphill get about 1/4 the normal mpg for gas, but the EV uphill is getting 1/2 the normal full range. The effect is probably closer to the same penalty for both...EV is probably worse, though. Mike
I only know the breakdown from my local PoCo. Their mix is 41% coal, so using 1 ton CO2 per MWh a full charge on my PiP should create about 2.5 lbs of CO2 emissions (the rest is wind, geothermal, solar, hydroelectric). That's the same as a 1/8 gallon of gas or so.
