ELROY
Well-known member
RLC said:ELROY said:I have no idea how Sean (Right Lane Cruiser) from Clean Mpg forum can get 5.9 m/kWh. I am driving, and accelerating as slow as I possibly can. I am taking all the side roads with no traffic, etc. Trying to keep the motor below 10kW when accelerating to even 30mph takes forever (while you are holding up traffic). Sometimes, I wonder if it is better to accelerate at 20kW and get up to speed sooner so you can level off on the throttle. Perhaps all this slow acceleration isn't much better than getting up to speed somewhat quicker?
Sean's economy data (Is he on this forum?)
http://www.cleanmpg.com/forums/showthread.php?t=45554&page=4" onclick="window.open(this.href);return false;
Re: Week of November 5th - November 11th (Nat Avg: $3.50)--------------------------------------------------------------------------------
I couldn't quite make the mark this morning. The relative humidity is fairly high and the windows kept fogging...
34F (29F windchill), 6mph tailwind from the NNE, clear:
•5.9 mpk (169.5 Wh/m) over 14.7 mi --> 198.0 MPGe (Home to work)
Day Total: 5.9 mpk (169.5 Wh/m) over 14.7 mi --> 198.0 MPGe
Tot. Used: 2.5 kWh
Adj. Cost: $0.38
Cost/mile: 2.6¢
__________________
- Sean
ELROY, DGPColorado is correct -- you shouldn't try to compare results from two different drivers in different climates with different terrain and traffic patterns too closely. There are simply too many variables to make it an easy effort.
With that said, I will echo what many others have said on this thread; the more you drive the better you'll get. I'm not unique in managing high miles per kWh numbers (though perhaps I achieve them in somewhat colder temps than most) but my habits behind the wheel are about as far removed from the typical driver as you can get. I've been honing my efficiency skills for many years now and though I've only had an EV for 8 months, energy efficiency is pretty much the same regardless of onboard fuel source.
When it comes right down to it, momentum conservation is the main goal. Ditch cruise control because it aims for constant speed instead of constant power use (a trained right foot is much better). Driving in such a way that you don't need to use regenerative (or worse yet, friction) braking to slow down in most cases and you'll avoid the conversion losses (and just plain losses) associated with those mechanisms. It is always better to keep the vehicle moving than to change the momentum, though you can play games with exchanging kinetic energy and potential energy (useful for getting over hills) which allow changes in speed without as much of an efficiency hit. If you imagine what you would do on a bicycle with no brakes, you'll have the right idea; speed up on flat land and downslopes where it isn't as hard to gain momentum, slow down as you go up hills, speed back up on the other side, coast to stops, and try to time lights by adjusting your speed to the average needed to arrive just as the light turns green.
There is no one magic technique which will get you higher numbers but there are a lot of little things you can do which will add up to big differences. Driving in traffic (which I've done all over the country -- notably LA, Chicago, Atlanta, NY Times Square, Washington DC) requires very different techniques for efficiency than driving on the highway. Most of the techniques have been discussed to at least some extent in the forums here but if you'd like a cohesive picture of the whole spectrum and how they are used together from one person you are welcome to PM me for offline discussion.
Hey Sean, nice to hear your insight. Still amazed at how you can average over 6mi/kWh on over 50 miles of driving some days. All this hypermiling makes perfect sense to me. Just trying to figure out how much acceleration to give it when leaving an intersection. Again..very slow acceleration (2-5kw) and taking forever to hit 30mph vs accelerating at 10-20kw and leveling off much quicker into coast mode, etc.
I just finished testing tonight on this current charge of 80%.
Driving techniques:
Acceleration: Usually under 10wk till the regen disappears around 15-25mph or so, then immediately lifting throttle between 0-3kw or so.
Speeds: Lots of driving 18-20mph in 25mph zones, and 25-30mph in 45mph zones.
In other words, staying awaying from traffic, going as slow as possible to keep the economy gauge as high as possible. Just taking my sweet old time when driving, lol.
So I finished my total test run of 81.3 miles with the following stats:
50-55F temps.
160ft elevation approx.
No significant grades. Essentially level runs everywhere.
44psi tire pressure in all four tires.
80% charge. ECO mode for majority of driving.
61.2 miles for LBW (1 bar showing, 11 miles range indicated)
74.6 miles for VLB warning.
81.3 miles for total test. (same 6:00hr estimated charge time as last test above)
5.4 miles/kWh total economy for the 81.3 miles.
So while I am pleased to have achieved 80 miles, it took some painstakingly slow/careful driving. I am pretty familiar with most of these hypermiling techniques. I have achieved fairly high MPG numbers in my previous BMWs. I have averaged 47mpg in my 335d with a 70mph average on a 28 mile trip (36mpg EPA rating). For this 5.4 mi/kWh test session I tried to pace the traffic lights, and short of running stop signs, tried to conserve momentum. Part of this did include 10 miles of fwy driving (55mph), and probably 4 full throttle sprints to 40mph (road rage, lol). So I could probably have achieved even higher than the 5.4 number.
Sean, I know you were thinking you could get 100 miles on an 80% charge, Is that correct? Or do you achieve that regularly? And secondly, If it is so that a 80% charge is about 18KW usable. Shouldn't a 5.4m/kWh x 18kW run come out to about 97.2 miles? And if so..that is where my concern is. Isn't my 81.3 miles a little on the short side still? I'm wondering if my battery capacity may be a little compromised, as I felt it has been from the day I got the car. Battery temp is always around 5 bars. Never quick charged the car, etc.
I will find out exactly how long it takes to charge the car this a.m. I am assuming it will be somewhere around 5 hrs though. L2 16A EVSE upgrade. Assuming the 6hrs predicted vs 5hrs actual is normal,, and not an indication that my battery is not absorbing a full charge?