[XJ12]

Got home yesterday after completing my 1930 mile trip. On the trip up where I covered 876 miles, I mostly followed the charging levels that I had plotted out with ABRP. Although I had adjusted ABRP's efficiency to 3.9 miles/kWh @ 65 mph (the setting is actually 255 Wh/mile). I found that I had to watch my speed by driving slower so that I would arrive about the time the car would start warning me that I needed to charge soon. Door to door my trip took 19 1/4 hours with 4 hours and 11 minutes of charging with six stops on the road. Googling the trip says it should take 13 hours, but my first leg was much slower as I was trying to cover 250 miles with a car that has an EPA range of 238 miles. But what really caught my eye, was on my return trip from Fort Worth area to southern New Mexico of 674 miles that had about the same amount of charging time at 4 hours and 15 minutes also in six stops. I drove much faster where a good portion was 80 mph and it was windy so my efficiency may have suffered a little. So had to charge longer to make up for it. Just taking the distance divided by the total time taken, the slower drive up was averaged at 45.5 mph and the one faster shorter drive down that took 14 1/2 hours averaged out to 46.5 mph. So faster barely beat the slower. Pretty much a wash.

 

[NewsCoulomb]

Well, I got more stick time with Energy Assist. Got totally frustrated trying to find chargers with it. I didn't use it to plan a trip, but only entered in my next destination city while I was finishing up charging. It would start showing me predicted arrival state of charge. When it would show about 20% at my destination I would unplug and start driving. Then I would watch it as I drove to maintain at least above 10%.

Interesting that you say that. Most people have noted that Energy Assist provides a far more accurate efficiency estimate for the Bolt EV. You were arriving with between 10% and 20% (it sounds like), so maybe it was fairly accurate.

Got home yesterday after completing my 1930 mile trip. On the trip up where I covered 876 miles, I mostly followed the charging levels that I had plotted out with ABRP. Although I had adjusted ABRP's efficiency to 3.9 miles/kWh @ 65 mph (the setting is actually 255 Wh/mile). I found that I had to watch my speed by driving slower so that I would arrive about the time the car would start warning me that I needed to charge soon. Door to door my trip took 19 1/4 hours with 4 hours and 11 minutes of charging with six stops on the road. Googling the trip says it should take 13 hours, but my first leg was much slower as I was trying to cover 250 miles with a car that has an EPA range of 238 miles. But what really caught my eye, was on my return trip from Fort Worth area to southern New Mexico of 674 miles that had about the same amount of charging time at 4 hours and 15 minutes also in six stops. I drove much faster where a good portion was 80 mph and it was windy so my efficiency may have suffered a little. So had to charge longer to make up for it. Just taking the distance divided by the total time taken, the slower drive up was averaged at 45.5 mph and the one faster shorter drive down that took 14 1/2 hours averaged out to 46.5 mph. So faster barely beat the slower. Pretty much a wash.

All told, I would say those are both relatively slow average speeds for the Bolt EV. When I was testing the MY 2020 Chevy Bolt EV, I was able to maintain 50 mph over 1,100 miles one day, and that included a charge to 100% midway in order to reset the battery. Had I not driven the exact posted speed limit or charged to full, it would have been much, much faster. Even my personal 2017 Bolt EV can average over 50 mph for my regular 500-mile trips. In actuality, the trips are most often 480 to 490 miles, but I commonly complete them in about 9 hours 30 minutes.

A lot of factors can affect that average trip speed, though, including both the speeds of the chargers and the gaps between DCFC. If you have to charge past 70% regularly in the Bolt EV, it will really start to affect your trip speeds.

 

[GetOffYourGas]

Well, I got more stick time with Energy Assist. Got totally frustrated trying to find chargers with it. I didn't use it to plan a trip, but only entered in my next destination city while I was finishing up charging. It would start showing me predicted arrival state of charge. When it would show about 20% at my destination I would unplug and start driving. Then I would watch it as I drove to maintain at least above 10%.

I have played around with Energy Assist from time to time. Just for fun I occasionally have it route me to one of my saved locations. I was very pleasantly surprised when it suddenly routed me through the North Country (that section of NYS north of the Adirondacks, but south of Canada), using a DCFC in Canton I wasn't even aware existed. I checked PlugShare, and sure enough it had appeared out of nowhere.

Not all of my experiences have been good, though. Lately, it can't seem to find any DCFCs even though I know they are there. Trips it has routed me on many times are now suddenly out of reach for it. It's like it forgot about entire networks. Other times it tells me to park at an L2 for 8 hours in the middle of a 300-mile trip which makes no sense. If you HAD to use L2 on this trip, you certainly don't need to do so for 8 hours. And then it has me arriving at my destination at something like 65% SoC.

I haven't thought to use it the way you describe, though. I will give that a try on my next trip. When I travel, I tend to be very conservative. I try to keep my "min range" on the dash to greater than my remaining distance. This seems to leave me with a nice 20% buffer or so.

 

[sundog]

Well, I got more stick time with Energy Assist. Got totally frustrated trying to find chargers with it. I didn't use it to plan a trip, but only entered in my next destination city while I was finishing up charging. It would start showing me predicted arrival state of charge.

That's interesting: that's exactly how I use ABRP on a trip. While I'm charging at DCFC #1, I use ABRP to map a simple trip to DCFC #2 (temperature, road conditions, speed) and see how many KWH the next driving leg should consume. That helps me decide when to unplug from the charger.

Maybe I should try Energy Assist for that? Also, I don't get real-time anything right now (though I have read it's possible in ABRP). It would be cool to get a real-time warning if a headwind kicked up from 5mph to 20mph, and my efficiency dropped by 1 mile/kwh.

 

[XJ12]

A lot of factors can affect that average trip speed, though, including both the speeds of the chargers and the gaps between DCFC. If you have to charge past 70% regularly in the Bolt EV, it will really start to affect your trip speeds.

Especially when I was driving faster, I had to charge more because of the spacing. Here's my spreadsheet of the trip:

 

[sundog]

Another case is "slow DCFC": a route I take requires a stop at a "25kw" chevy dealer DCFC, which often gives about 18kw.

Let's say the chevy dealer is 100 miles from the previous stop. I'll estimate consumption at speed using Tony Williams' LEAF Range Chart (just because I have it in front of me):

• I could drive 100 miles @60mph = 100 minutes and use 23.26 kwhr
• I could drive 100 miles @70mph = 86 minutes and use 27.78 kwhr
  • plus 15 minutes charging at 18kw to compensate = 101 minutes
• or I could drive 100 miles @75mph = 80 minutes and use 30.3 kwhr
  • plus 23.5 minutes charging to compensate = 103.5 minutes

If you add the heater or HVAC while driving, then driving 70mph and heating for 15 minutes less wins. But if you sit in the car at the DCFC with the heater running for 15 minutes, then you lose that advantage.

If you add a stiff headwind (say 10 to 15mph) to your 70mph, then that would make your consumption look more like 80mph. That could tip the scales towards driving slower. I think the break-even point (when charging at 18kw) could be at around 19kw or 20kw consumption (at whatever speed that is for your driving conditions).

 

[NewsCoulomb]

Another case is "slow DCFC": a route I take requires a stop at a "25kw" chevy dealer DCFC, which often gives about 18kw.

Let's say the chevy dealer is 100 miles from the previous stop. I'll estimate consumption at speed using Tony Williams' LEAF Range Chart (just because I have it in front of me):

• I could drive 100 miles @60mph = 100 minutes and use 23.26 kwhr
• I could drive 100 miles @70mph = 86 minutes and use 27.78 kwhr
  • plus 15 minutes charging at 18kw to compensate = 101 minutes
• or I could drive 100 miles @75mph = 80 minutes and use 30.3 kwhr
  • plus 23.5 minutes charging to compensate = 103.5 minutes

If you add the heater or HVAC while driving, then driving 70mph and heating for 15 minutes less wins. But if you sit in the car at the DCFC with the heater running for 15 minutes, then you lose that advantage.

If you add a stiff headwind (say 10 to 15mph) to your 70mph, then that would make your consumption look more like 80mph. That could tip the scales towards driving slower. I think the break-even point (when charging at 18kw) could be at around 19kw or 20kw consumption (at whatever speed that is for your driving conditions).

The LEAF (per Tony's chart) is far less efficient than the Bolt EV. Remarkably so given how similar they appear on paper, but that was a different argument that Tony and I have hammered out in the past.

Regardless, yes, the maximum speed you can drive for best time does shift based on the speed of the available chargers. With access restricted to 24 kW DC chargers, 55 mph likely is the breakeven speed for best trip times in the Bolt EV. With only L2 AC, that drops to 35 to 45 mph. With only 100 A DC chargers, it's closer to 65 mph. With 125 A DC chargers, it's about 70 mph. And with >150 A DC it's nearly 80 mph.

Charger spacing also plays into this. The more you have to charge past 55%, the less 150 A charging really matters. And the more you have to charge past 70% the less 125 A charging matters.

I created a chart based on where the Bolt EV reaches parity with different chargers based on the mi/hr charging rate at that efficiency. I'll have to revisit this because, while the data is correct, parity between charging times and driving times does not necessarily result in the fastest trip times. Really, what it provides is the point at which you are driving (exhausting energy) faster than you can put it back in, so it's the foundation for the best trip speeds given available chargers but not the final number.

For example, the actual best trip speed time for the Chevy Bolt EV involves 77 mph driving speeds with access to >150 A chargers every 110 to 120 miles even though the Bolt EV is charging at >150 mi/hr on 150 A chargers based on its efficiency at 77 mph.

 

[sundog]

Interesting consumption numbers, NC. If I plug those in to my example, I get:

• drive 100 miles @55mph = 109 minutes and use 20.49 kwhr
• drive 100 miles @60mph = 100 minutes and use 22.88 kwhr
  • plus 8 minutes charging @18kw = 108 minutes
• drive 100 miles @65mph = 92 minutes and use 25.56 kwhr
  • plus 17 minutes charging @18 kw = 109 minutes
• drive 100 miles @70mph = 86 minutes and use 28.49 kwhr
  • plus 27 minutes charging @18kw = 113 minutes

Using those consumption numbers, I think I come up with 60mph as ideal speed if next DCFC is 60A ("25kw" or "24kw"). But really, the total time is within 1% of that for any speed between 55mph and 65mph. I'd probably pick a speed in that range based on other factors.

 

[NewsCoulomb]

Interesting consumption numbers, NC. If I plug those in to my example, I get:

• drive 100 miles @55mph = 109 minutes and use 20.49 kwhr
• drive 100 miles @60mph = 100 minutes and use 22.88 kwhr
  • plus 8 minutes charging @18kw = 108 minutes
• drive 100 miles @65mph = 92 minutes and use 25.56 kwhr
  • plus 17 minutes charging @18 kw = 109 minutes
• drive 100 miles @70mph = 86 minutes and use 28.49 kwhr
  • plus 27 minutes charging @18kw = 113 minutes

Using those consumption numbers, I think I come up with 60mph as ideal speed if next DCFC is 60A ("25kw" or "24kw"). But really, the total time is within 1% of that for any speed between 55mph and 65mph. I'd probably pick a speed in that range based on other factors.

Yes, there's definitely a range of speeds. With >150 A chargers available, the Bolt EV's range of speeds is 75 mph to 80 mph. After 80 mph, you'll start to lose a bit, but you still might be traveling faster than you would at 70 mph. Also, this is really just a general rule.

In the real-world, if you're driving to a >150 A DC fast charger with the next charger after another 100 to 120 miles away, you're best trip speeds will be driving as fast as possible to the first charger (while still being able to make it, of course). Basically, driving 80 to 85 mph and arriving with 5% battery will likely be your best trip time.

On the other hand, if the first charger is a 24 kW unit, you might want to drive slow enough that you can almost skip the charger altogether (within reason, of course).