Is there anyone else with a Prime who has experimented with maximizing EV mi/kWh and learned something that you are willing to share? I've had my Prime for 2300 miles and still learning. I typically get around 5 to 5.5 mi/kWh when running in EV mode. But I started doing what the owner's manual says to maximize range in EV ie accelerate very slowly and maintained lower speed while I drive my short distance to work with little if any traffic. Doing what the owner's manual said I got 6.5 mi/kWh on my first try round trip to and from work keeping the speed under 25mph. But then I noticed while watching the instanteous mi/kWh meter that if I drove very slow, accelerating slowly I was only getting around 1-2 mi/kWh. But if I pulsed to get up to speed quicker, I used the same 1-2 mi/kWh and then glided to my stop sign or next turn where I would peak out and drive a long distance at 20mi/kWh the maximum on the gage. End result was 6.7 mi/kWh average going to work on the EV Daily Diary, and 6.9 mi/kWh average for the day after returning home that same day, meaning I probably got 7.1mi/kWh average for the trip home of the same distance. So on another day I drove up to 45 mph on a pulse then glided for 3/4 of a mile much longer than before. I only got 5.5mi/kwh on that trip. So it seems the maximum mi/kWh I could get so far is by pulsing and gliding to a max speed of 25 mph. Please share your EV maximizing mi/kWh experience.
What I do is calculate the drag HP as a function of speed. Since I'm more interested in MPG, I generated this chart: 28 mph - the lowest speed the cruise control will hold should be used for your maximum range "mi/KW" MPG - includes a vehicle overhead factor More details: Prius Prime Plus in my hands | PriusChat Bob Wilson
the motor probably has an efficacy curve. if you could find it, pulsing to those rpm's and gliding might work.
Since it's a PM motor, most (but not all) of the losses are copper losses. The upshot of that is that it's more efficient at lighter load. That would indicate the best strategy would be the smoothest possible application of the necessary torque - the opposite of pulse and glide. Pulse and glide works with the gas engine because it is more efficient at heavier load.
makes sense, but not in gen 3 for me's case. i have never had any luck trying to pulse and glide in ev.
My understanding is that pulse and glide is meaningful only for HV mode, and is an attempt to use the ICE in a more efficient range. This is relevant in HV mode, since ultimately, ALL of the energy is coming from the ICE. EV mode and electric motors are a completely different beast.
smoothest possible application of the necessary torque Yes this means the same to me as the statement in the Owners Manual on page 101which provides tips for extending EV driving range: Accelerate and decelarate the vehicle as smoothly as possible. Another tip is to drive at moderate speeds as much as possible and maintain a constant speed. I believe I misled unintentionally in my original post with my use of the term pulse and glide. What I actually was doing when I got the 6.9 mi/kWh avg on the daily diary screen was to accelerate gently getting somewhere between an estimated 1-2 kWh, but I kept accelerating to get to a higher speed, around 25 mph, and then held that speed until I knew I could coast to the next stop sign or next turn. When coasting I kept my foot on the acceleration pedal gently to not invoke the charge mode. During the long "coast" the meter reads 20 mi/kWh.
Taking your example of mpg vs mph in ICE mode made me ponder how I could best do this for EV mode without any instrumentation. The instantaneous mi/kWh bar graph is very difficult to interpolate with lines at only 0, 10, and 20 mi/kwh. But I plan to switch to metric to get more sensitivity by plotting kWh used every 1 km as shown on pages 218 and 219 of the owners manual. up to the latest 15 km can be plotted. I will hold a steady speed on flat ground recording the avg km/kWh and drive the same stretch of ground at other speeds to make my graph. A plot of km per hour vs km/kWh will result. I'll report back in probably a few weeks after I get this done. If there is a better way without instrumentation please let me know.
Try to use video capture with a cell phone. You can play it back later and get usable metrics. Bob Wilson
Thanks for the video tip. I wish I could find a loop close to my home like you found to drive on to eliminate slowing for changing direction and to minimize the amount of driving I need to do. Will do early morning to minimize effect of wind gusts.
I hit 10.2 mi/kwh last week in hybrid mode drafting a semi at 62mph with 1 bar of cruise distance. The car did pulse and glide with the cruise maintaining 62mph. EV range would go up 1 mile, then the car switched into EV mode until the EV range dropped about 1 mile, then back to HV mode pushing the car and charging the battery. It seems that I get between 75 and 79 MPG in that state. I have 350 miles to drive tomorrow and I am going to try the same technique, but at 2 bars of cruise following distance. 1 bar of cruise was only 1 second at 62mph. The semi serves 2 purposes, first is to reduce wind resistance(this will drop at 2 bars), the other is to keep cars coming up behind me from running me over while doing 62mph in a 70mph zone. I am a little concerned that the semi will be less effective for both purposes at 2 bars. I will update tomorrow evening.
Could not use 2 bars. It was too far back most of the time. At 1 bar I was 1-1.5 sec back. CHP passed me twice without issue. Faster trucks today, 63 and 64 mph. 320 miles, 74.9 mpg, 7.2 mi/kWh, all 32.5 EV miles used up. Total lifetime miles/gallons of fuel pumped = 67.76mpg. Approaching 4K mi. 95% freeway
So far I have found out that metric is difficult to use because the metric scale flips numerator and denominator to 10kWh/100km which is equal to 1kWh/6.23 mi or 6.23mi/kWh as opposed to the english scale which maxes out at 20mi/kWh. So far the best I have done is 16mi/kWh for 1 mile while slowing down from the highway into town, and 7.7mi/kwh daily average over 31.1 mi in a single trip, avg speed 16 mph. The metric scale might be useful for slow speed testing. It is difficult to hold a steady speed at low speeds since cruise does not work if I start below 28mph. I now have a remote test route located and I drove it once. I need to repeat my slow driving at set speeds to make a plot like Mr Wilson did. Prelimimary rought data indicates that slow speeds will yield the most mi/kwh. Not surprizing at all, and not practical at all for daily commuting, in fact it would be dangerous on public roads. More information will hopefully come later probably after spring planting is finished. On the day I drove to and on my new test route I started with a fresh charge at 35.0 mi EV available. I drove 31.1 mi had had 11.4 mi EV left. Calculates to 42.5 mi EV on a charge.
I AM NOT ENCOURAGING ANYONE TO DRIVE THEIR CAR SLOWLY. SERIOUS RISKS ARE INVOLVED. With that legal disclaimer clearly stated I will now explain what I did under controlled conditions. I have a 4.35 mile narrow paved driving route that has three 90 degree corners which makes driving at a constant speed in EV mode not possible at speeds above 25 mph due to having to turn the three corners. Being able to cruise control would have made this experiment easier and more accurate. I had to do my best to hold steady speeds of 25 then 20 then 15 mph to evaluate the speed where the greatest mi/kWh in EV mode. If my speed dropped below the nominal speed for a certain distance I compensated by going over the nominal speed by the same amount for the same distance to maintain the nominal speed as the average. Always started and stopped at the same point on the route. Used my typical gentle starting habit that provided 1-2 mi/kWh until I reached the nominal speed. Results: 15 mph nominal speed gave the best result of 6.5 mi/kWh as expected. Experimented with a different starting technique which I will call: Easy-On and Glide Easy On means take foot of brake pedal and wait until the real time bar graph reads between 10 and 20 mi/kWh, Then gently use acceleration pedal to reach desired speed and maintain speed. Glide means take foot mostly off acceleration pedal so 20 mi/kWh is shown on real-time graph to coast to next stop or turn needing no speed or a slower speed. (I try not to activate the charge mode during gliding and therefore maintian some very slight pressure on pedal and to get the most distance out of the glide.) Running the first mile of the same route with Easy On at 10 mph yielded 10 mi/kWh (no glide used). Stopping at the beginning of the 2nd mile and using Easy On to get and maintain 15 mph for 1 mile (no glide used) yielded 8.5 mi/kWh. (Compare data in table below to Gentle EV Driving) Optimum Condition Easy On - Glide Trial Early Sunday AM Drove my routine round trip home to work to home with no traffic. Averaged 9.25mi/kWh at a nominal speed of 15 mph. Typical driving condition Easy On - Glide Tuesday at 7 AM Drove to work. Very minor traffic - 1 car behind me for last 1000 feet so pressure to not drive at nominal speed 25 mph, top speed estimate 28 mph. Yielded 6.9 mi/kWh
mi/kWh at end of test route driving and drive home shown in first photo below driving in Easy on - Glide mode on routine drive home-work-home at nominal 15 mph zero traffic -2nd photo 3rd photo is data in table
Summary: All from a stopped start: Standard Gentle EV driving at 25 mph under ideal controlled conditions = 6.125 mi/KWh over 4 miles Standard Gentle EV driving at 15 mph under ideal controlled conditions = 6.5 mi/KWh over 4 miles Easy On - Glide Driving with minor traffic - Nominal 25 mph but up to 28 mph = 6.9 mi/kWh over 1.1 mile Easy On - Glide Driving under ideal conditions at 15 mph = 9.25 mi/kWh over 2.2 miles
I hit a new record for me today of 13.7 mi/kWh. Reno to Folsom is mostly downhill. I engaged EV mode at Donner Summit with 21 miles of EV range on the GOM, and made it to my destination still in EV mode 85 miles later with 0.1 miles left on the GOM (7000 ft drop). DRCC at 1 bar behind semi's. 90+Fahrenheit at the bottom of the hill. 125 miles, 141 mpg. Less than 1 gallon Reno to Folsom with AC.
