How does the GOMs history really work (city vs country driving)

[Cain]

up until last weekend I was astounded by how accurate my Kona's GOM is. I have a very consistent 150Km each way commute, all highway driving, with the cruse set on 105. Same goes for my first longer trip up to Bathurst (a 900Km or so round trip).

e.g. If I leave home at 80% charge with 320Km range indicated. I drive 150.4Km to work and will have something like 174Km range left at the end.

Then last weekend I went to Sydney. All good on the way there (303Km so I charged to 100% just in case, but had loads left on arrival). I then drove around all day doing about 90Km in the "legendary" Sydney traffic.

I then topped up before the trip back to Canberra (nice fast 45 min L3 charge to 80% while I had a morning cuppa). I don't remember the exact range value at the time but it was about 370Km. So I had 68Km spare. It should have been enough headroom.

50Km into the return I hit the freeway, set the cruse on 115Km.hr and watched the gap between GOM and the sat-nav shrink. 68Km of headroom shrunk to 29 by the end. I then did a splash and dash for that final 150Km leg home (highway driving). This time I gave myself 50Km of headroom between GOM and sat-nav thinking highway should be better than freeway so if anything the gap should increase.

Or so I thought.

By the time I got home I had 9Km of range and had hit turtle mode! For the last 60Km I was in Eco+ and limiting my speed to 90Km/hr. Now the elevation difference along the trip could play a part. Sydney is essentially 0M ASL, Canberra 577M ASL and Home is 1100M ASL. But from previous experience, I really didn't expect the gap to be more than 5-10Km.

I've heard about city driving being more efficient than country, and I did notice that I was consuming only 9.9KWhr/100Km in the city vs my usual 15.8KWhr/100Km, but I expected the gap to drop when I hit the freeway initially, then settle once I was 30 or 50 Km into that style of driving. I also didn't expect the Canberra to home leg to have much of a gap drop at all.

But what I observed was a more gradual drop that persisted not only for the whole 250Km freeway leg, but into the 150K, highway leg as well. It seemed faster initially, but without a rigorous data collection strategy, that's hard to quantify.

Does anyone else have anecdotal, or empirical data on how the GOM uses "previous driving history" to determine range?

 

[hieronymous]

I doubt you will get empirical data, each driving experience for every driver is essentially unique, but anecdotes abound..
Your drop-off in range doesn't surprise me, I wouldn't have attempted the return leg without a 100% charge. The Kona is a heavy, SUV designed vehicle, with relatively poor aerodynamic efficiency, which means its economy quickly worsens at higher speeds. Throw in steady climbing to 1100m, which I have seen add 1-1.5kWh/100km to the result, means your outcome is normal.
I'm surprised you think your GOM got to about 370km @80% in Sydney when your everyday charging gives you 320 - I would not expect the GOM to change that much or that quickly. When I charge to 100% my GOM result never varies more than 10km whatever driving I have just done..
Speed makes a huge difference (not that there is always a great choice). Yesterday I drove 425km, 100% charge, cruise control @95kph. The route climbed 2 ranges, 200m and 500m. I got back with 13% SoC left, and averaged 13.0kWh/100km, meaning about 485km to turtle. Without the extra hills I normally get about 500-520 (extrapolated), 12.5-12.7kWh/100km, at that speed.
My EV experience, including 4 years with a Leaf, has shown me that on a trip like that the GOM starts to adjust slowly, then quickly settles into a rate that will persist to empty (assuming steady driving). The Kona also seems to me to get a little more out of the top half of the battery than the bottom, which perhaps suggests erring on the side of conservative i.e. higher charging levels before setting out...

 

[Cain]

Interesting observations. It would seem that what I saw was a result of altitude, and a fairly significance change between 115Km/hr on the FWY and 60Km/hr (if I was lucky) in the city. I've taken careful notes of what kWhr/100Km I got on this last trip "downhill" from home with no accessories, no wind and constant cruise control speed. And I'll compare it to the return. That should at least allow me to see what difference the uphill nature of that trip did to the GOM.

More to come

 

[556x24]

You didn't state your speed on the trip out, but the difference between 105kph (65mph) and 115kph (71.5mph) is essentially across the line where the Kona starts to show rapid use of available range due to increased wind drag.
I town with plenty of stop & go with regen the Kona can easily achieve 4.4 mi/kWh, and if one learns how to skillfully integrate coasting with regen 5.5 mi/kWh is possible, and once can see add so much range through regeneration that 300+ miles of range is easy.
If you've been doing a lot of "town" driving which is causing the computer to "think" your getting much better efficiency, it will alter the display accordingly. When you get on the freeway where continuous steady-state driving at speed is the worst possible energy use parameter, what you will experience is the car suddenly telling you it's using up available range much more quickly and you'll note a certain range remaining, look away for a few minutes, look back and suddenly see the range had dropped dramatically. This is because during that viewing interval the computer displayed an updated estimate based on your much higher current draw. This is why it's good to know your baseline range numbers and plan to them rather than rely on the range remaining "within" a long trip.

Also, when driving at speed on the highway, running about 62mph seems to be substantially less consumptive than kicking it up to 70+ where you can literally starting watching the miles tick down! This ends up LOOKING a lot worse when your computer has been displaying a range remaining based on town driving and suddenly updates to the new power draw.

During my daily 40 mile each way commutes with mixed surface street and freeway, I've discovered I can basically "match" range available to distance driven by running full regen at around 60-62mph. This is minimally impacted by adding AC, a bit more so by using heat. When I got to 65mph the increase use of range starts to show, and at 70mph I can quickly see my range dropping faster than miles driven. At 75, the effect is profound. A few weeks back I left work with probably 60% SOC after having driven according to my "standard economy" practice which splits the difference between maximum miles and time to arrival. On the way home I running down the freeway, traffic opened up some and I felt like experiencing the "fun" of driving the Kona fast, so I picked up to 75-80 mph. I don't remember the range remaining exactly when I "opened it up" but I do remember it was over 100 miles. As I was enjoying my run down this long straightway, I glanced down at the display only to be shocked when I saw my remaining range was suddenly just 65 miles! I could swear when I pulled out of work I had at least 125 more on tap and I had only driven about 20 miles! So what happened? Well, several things I think - the range available was based on a more economic previous driving profile where I commonly hold my speed down under 65mph. Over the previous 10 miles or so of freeway driving I had been so engrossed in driving faster and using the Kona's superior torque to surge around traffic that I was certainly running draw rates well over 35 kWh consistently! Well, we already know that turning on the heater with a whopping 3 kWh draw results in a sizeable reduction in range displayed, and here I was pulling twice the normal draw and holding it!
Now, after I reduced speed the "rate" range decrease dropped substantially as the computer recalculated I was going to make it farther than 65 miles. The range display didn't go back up, but it did stop going down as fast so I was basically covering more miles than the display was ticking down.
Yesterday in the early morning with temps in the mid-40's (F) when I left work I needed to get home faster so I ramped my speed up to a solid 75mph, PLUS I had activated heat during the initial portion of the trip! I started with 125 miles available range and by the time I got how was down to 57. I burned 68 miles of range over a distance of 47 miles for a solid 45% INCREASE in range used for distance driven! And that was only driving "fast" for the latter portion of the trip. Had I been pushing it the entire distance I certainly could have seen a lot more range used up.

When I plan trips that will require charging en-route I plan for no more than 200 miles per FULL charge to compensate not only for the variables I know, but also the ones I don't. Even with that, I'm making my calculation on a given miles/kWh expectation that I must be careful not to exceed. Then I look for DCFC points about 100 miles apart, and no further than 125 miles apart. When you think about how the battery charges quickly then slows, it's much faster to charge more frequently rather than drive farther and charge longer.

I don't know if others have discovered this - I'm sure many have, but the Kona has better efficiency on the freeway with full regen ON rather than off as one would suppose considering the drag produced by regen. I THINK this is because the Kona's regen is so efficient it actually exceeds DCFC speed, so when using regen while drawing from the "net" is less power drawn...this can be observed real time by having the center display set to show kWh use and cycling through regen settings while maintaining a steady speed. It can also be seen in overall miles/kWh over distance. On the other hand, for city driving with plenty of stops and opportunities to coast between traffic lights, I find that accelerating with two bars of regen to a few mph over the posted speed, then going regen OFF, while lifting off the accelerator to coast to the next light, then adding regen back in as needed to slow and stop is how one achieves maximum range. I have seen 6 mi/kWh and sustained 5.5-5.9 mi/kWh using this technique, whereas using full regen ON all the time seems to top out at around 4.4 mi/kWh. Due to the efficiency of regen, it SEEMS to be better to accelerate quickly rather than follow the "eco" green band guide (regen on), then go "coast" as soon as speed has been achieved. The car draws less total current with a rapid (but not crazy) acceleration that's over quickly as opposed to pulling juice at a lower rate for a longer duration. In essence you'll get more back during regen than you'll use during acceleration and sure enough if you watch your regen numbers on the center display you can see "-kWh" numbers go much higher (meaning you're putting juice back) during regen than you'll see going out during acceleration. The highest I remember seeing kWh usage during hard acceleration is high 40's, and I've seen regen -kWh in the 60's. I remember reading where someone claimed the Kona EV has 150 kWh capable regen.

 

[Cain]

Updating this thread with some results from the last few weeks of commuting. I can report that Altitude difference makes much more of a difference than I expected. The difference in kWhr/100Km going downhill from 1100M ASL to 570M ASL vs uphill is about 3kWhr/100Km. In my case 15.4 downhill and 18.5 uphill. All other things being equal.

Crunching the numbers for that 150Km trip, it comes to 30Km one way or the other. The good thing is, once you know that, it's predictable. Basically 100M of altitude equals 5Km of range. I'll do one final test this weekend as I'm going down to the coast. So Based on that I'd expect to add 25Km of range on the journey down.

There's also a site called https://abetterrouteplanner.com which a Tesla owner put me onto. It takes into account altitude, and you can set driving speeds etc. Very cool.