I'm not entirely sure I'm correct in how I've been using this.

How do you suggest determining the number to plug in here?



My car is a 2019 Audi E-tron, US "Premium Plus" edition, 20 inch wheels

when I plug in my car using ABRP's pull down list, it changes the reference consumption to 2.59miles/KWh



My car reports and average of 2.5mi/KWh..average over the life of the car.

I have been using 2.4mi/KWh in ABRP for my planning to date just to include a safety factor.



Recently I finally read the "fine print" and see that this variable field is AT 65 MPH!

Am I correct in assuming that they use this number as a basis, than adjust the plan based on the entered "extra weight" speed, hills on the route, etc...?



I just went out today and reset my short term memory trip display while the cruise control was set to 65MPH. Traveled approx 5 miles on a flat section of interstate highway...and the display had settled on 2.8mi/KWh after a mile or two, but just ticked up to 2.9 as I had to slow for my exit. A few minutes later I repeated this test in the opposite direction with exactly the same result.

So should I be using 2.8 or 2.9, and letting the algorithm adjust for the weight and variables along the route?
Should I run the same test for a further that the distance of 5 miles, to get a better average?

I asked this question over on the ABRP site, but seems like that's not a highly trafficked thing so I thought I'd copy it here to you knowledgeable folks too, for faster response + more E-Tron specific knowledge....

 

I believe the 2.59 is specifically for 65mph since it is a reference. It should factor in the difference in energy usage based on the speed limits of the route you are taking. It will assume that you will be going the speed limit on the routes you are taking.

There is also the speed correction factor...so if you typically drive 10% over the speed limit, adjust your driving speed to 110% without changing the reference consumption. I’ve found 2.59 to be a decent number for me as it does already underestimate the range a little but YMMV.

 

Your reported efficiency is going to change quite a bit depending on driving conditions and weather. When I set up my ABRP app, I noticed that the app was using the WLTP values for the car's efficiency, which is very optimistic. I did not try to do exhaustive testing on my own car to try to come up with a number, but replaced the WLTP value with the EPA value, which seems to me to be much more realistic. I prefer to use the LEAST optimistic estimate for efficiency, since that reduces the chances that the app will cause me to run out of electrons before reaching the next station because it thought I could go further than I actually could.

 

I kept mine at 2.59. I do get slightly better results than predicted but I consider that my safety factor and it has not got me into any trouble and it’s quite predictable. I also thought about increasing it slightly to get full accuracy but until there is more charging stations I decided to keep it slightly conservative

 

I'm assuming that ABRP is using this number then applying the changes you mention based on the route (and weather for premium users). I recon they have to use something to define the 'car', then adjust for hills, speed variability, etc...
I suppose the underlying question is, how good is their algorithm for all these variables?

So what is the EPA value you use?

I too have preferred to err on the conservative side. In the few trips I've planned and taken I have noticed I can skip some of the charge stops ABRP has suggested, but I haven't really looked at what range margin over plan I've ended up with. I was ok with it regardless, but now I'm trying to drill down a little bit better in my planning.

 

Same here. ABRP has even said that their algorithm is slightly pessimistic on consumption to avoid stranding drivers: https://www.reddit.com/r/electricveh...eb2x&context=3

 

Well, my 2019 was EPA rated at 204 mi range with the car having a usable battery of 83.6 kWh. That works out to 410 Wh/mi. However INSIDEEV's (https://insideevs.com/reviews/343797...ast-among-evs/ ) listed an even worse value of 455 Wh/mi, base on "EPA Combined Consumption". Not sure why such a difference. but I use the very conservative 455 Wh/mi. Honestly have not used ABRP enough to decide it that was a good choice or not. What numbers do you use?

 

It’s better to be conservative in this case, of course. However I’ve found that in practice I don’t need as many stops as ABRP tells me I do. I’ve found I get the expected numbers but get it at 75-80mph, vs the 65mph.

I’ve currently got ABRP set at 390wh/mi and even that seems a bit conservative and throws in an extra stop compared to one of my recent trips.

Also, I appreciate that ABRP takes elevation into account and will show you a chart. Nice feature.

 

so far it seems the consensus is just to run ultra conservative with APRP
I get it...and for general purposes I tend to agree with that approach...just to have a "safe" plan...with no thought or stress required. Makes perfect sense.... sometimes
but
I'm having flashbacks thirty some odd years ago to the engineering lessons in college on factors of safety...and the tendency to add FS on top of a FS on top of another FS.... and the risks in doing that.
No doubt the algorithms in ABRP probably have several layers of factors of safety applied either on purpose or just from the result of rounding errors, safe guessing to cover unknowns, etc...

I was just hoping to learn how I might drill down to as close to precise as ABRP would allow.... and also learn just how good that might be real world.
....So I can drill down only just to whatever FS ABRP might have built in, nothing more....Then using that info I might be able to apply better judgement to make more efficient judgements of when and where to apply my personal and additional safety factors

 

side question....
seems like all of you so far are looking at watt hours per mile (wh/m)
instead of miles per KW
why?