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Road trip buffer

Percent buffer for supercharger road trips?

  • 0%-5%

    Votes: 2 2.2%
  • 6%-10%

    Votes: 18 20.0%
  • 11%-15%

    Votes: 24 26.7%
  • 16%-20%

    Votes: 27 30.0%
  • 21%-25%

    Votes: 15 16.7%
  • 26%+

    Votes: 4 4.4%
  • I don't take road trips, but I like to vote!

    Votes: 2 2.2%

  • Total voters
    90

Max*

Charging
Apr 8, 2015
6,672
3,719
NoVa
When you take a road trip, with a supercharger stop(s), what's the usual buffer you leave yourself (from the trip tab) to arrive at the next supercharger/destination.
 

dweeks

Member
Aug 26, 2014
242
73
Flagstaff, AZ
When you take a road trip, with a supercharger stop(s), what's the usual buffer you leave yourself (from the trip tab) to arrive at the next supercharger/destination.

6-10% on routes I know. If I was off my beaten track for the first time, probably 10-15%.
 

Vger

Active Member
Supporting Member
Apr 10, 2009
1,781
210
Salt Spring Island, BC, Canada
6-10% on routes I know. If I was off my beaten track for the first time, probably 10-15%.

That is about my strategy as well. Unexpected headwinds can still kill a predicted 10% buffer pretty quick. I will cut it close (5-10%) when I am confident of the conditions and know the route. If I am not in a hurry and in new territory, I often shoot for 15% or even 20%.

As Jack Bower pointed out at TMC Connect 2015, you have to watch the prediction in the early stages of a leg. It is often quite variable and unstable early on, and then gradually settles down during the final 50-80 miles of a leg.

- - - Updated - - -

0-5%. I live life on the edge.

I used to, but learned my lessons! On one trip, my battery was out of calibration, and it went from 2 miles RR to shutting down with no in-between! We literally pushed the car into the supercharger. My wife has still not forgiven me!

You also do not contend with mountains or deep cold down there. :wink:
 

Ugliest1

S85: "Sparky"
Supporting Member
Aug 19, 2013
1,401
1,645
Victoria BC Canada
I voted 11-15% but sometimes only leave 5-10%. My biggest problem with superchargers is the car is done before we're ready (I guess we walk slowly), so I end up with a 30%+ buffer!

Haven't done much in the really cold so far, if/when I do that buffer will be going significantly up (30% minimum) until I get used to what happens.
 

KJD

Supporting Member
Supporting Member
Dec 14, 2013
1,372
1,019
SLC, UT
I voted 16% to 20% but this will vary a lot according to how well I know the route and how many alternatives there are along the route. I also like to start the day with a 100% charge, because if you charge while sleeping it does not cost you any time and gives you more options for the next day.

I also like to plan a lunch break at a SC and often take extra time to read and write emails or read TMC while the car charges. If I am on vacation, I try and keep a relaxed pace. It is much less stress that way, compared to worrying about making it to the next charge location.

If after all that you still end up cutting it close on range, just drop the speed 10 mph and the battery will last much longer at a slower speed.
 

HankLloydRight

No Roads
Supporting Member
Jan 18, 2014
13,039
11,088
Connecticut
I said 20-25% because I like to have extra buffer and I like to drive fast and not worry one iota about range.

Also, once I got caught in a massive backup on the NJTP heading north into NYC and that sapped all of my buffer, I had to find alternate, slower than highway routes, but at least it was moving. Then I hit a detour around the route I wanted to take.. I think I arrived home with about 10 miles left. After that, I always spend an extra 5 to 10 minutes at the SC for just a little extra buffer.
 

ChadS

Last tank of gas: March 2009
Jul 16, 2009
3,357
2,750
Redmond, WA
There is a lot of stuff the energy estimator doesn't know - how fast you will drive, headwinds, weather changes, detours, etc.

Add to that the fact that all possible EV drama happens at the bottom of the battery, and I just don't go there. I used to always have a 50% buffer, but since the energy estimator takes some things in to account that that used to cover (like elevation gain) I no longer feel the need for that much. I try to always get at least a 20% buffer; and more is better if I'm not in a hurry.
 

Khatsalano

Member
Mar 21, 2015
669
116
San Mateo, CA
6-10% on routes I know. If I was off my beaten track for the first time, probably 10-15%.

Same.

For battery health, I try to use the 20-90% SOC range for all of my distance driving. But for very long road trips, I've gone down to 5% before when confident (like skipping Corning SC, from Shasta to Vacaville SC because it's mostly downhill and with the wind that day).

- K
 

martinwinlow

Member
Jun 18, 2012
362
-28
Isle of Colonsay, UK
As Jack Bower pointed out at TMC Connect 2015, you have to watch the prediction in the early stages of a leg. It is often quite variable and unstable early on, and then gradually settles down during the final 50-80 miles of a leg.

5-10% is my usual margin (and I have a MS60 - shouldn't we all be saying what pack size we have? - maybe most are at least 80s...?) but unlike Jack, I will monitor the difference between range remaining (RR) and distance to go (DTG) all the way through the trip... And this is the important bit - if that difference begins to fall then SLOW DOWN, say 5 mph and then monitor it for 10 minutes or so. If it steadies, then fine, carry on at that speed. If it continues to reduce, then you must slow down some more and so on until you either arrive or the difference stops reducing. This way it will be nigh on impossible for you to run out of energy.

Conversely, of course, if you find the difference between RR and DTG is going up, then you can afford to go a bit faster. Same rules apply. Bear in mind, however, that ideally, you want to arrive at your next SuC stop with as little RR as possible as, that way, the charging time is minimised for your next leg. This may not be the best strategy for battery longevity, of course.

One last issue is the affect of elevation change on RR. After a recent 1000 mile round trip to Scotland, it was quite noticeable that the RR started falling significantly as I climbed up into the Highlands. However, coming back out of them the RR increased again. Over 50 miles between going into the high ground and coming out again I lost and regained about 20% of my RR (the max increase in elevation was ~900 feet). MW
 

jerry33

(S85-3/2/13 traded in) X LR: F2611##-3/27/20
Supporting Member
Mar 8, 2012
19,958
23,896
Texas
When posible, 20% or more. An unexpected head wind can really eat range.
 

Max*

Charging
Apr 8, 2015
6,672
3,719
NoVa
I try to hit 6%-10% buffer, and we try to maintain 70-75mph speeds. At those speeds, the trip tab doesn't really decrease/increase between long SpC legs (70D, if it matters)

The "issue", is that for example heading home last night, stopped by to get a charge. Only needed about 10-12mins charge to get home, but I couldn't get my kids back in the car for another 20mins (ended up at the SpC for ~30mins, instead of 10), so I had a much bigger buffer than intended. Also, on longer roadtrips, we try to plan meals around the longest SpC stops, so often times we end up with a much higher buffer than intended too.

So far, only taken summer trips. In the winter, I need to see how accurate the trips tab is, maybe I'll stick with 6%-10%, maybe I'll bump it up a bit... (I'm also on the east coast, and for the trips we take often, we often skip several SpCs, so I know if I see my buffer go way down, I can stop earlier)
 

mknox

Well-Known Member
Aug 7, 2012
10,103
1,870
Toronto, ON
So far, only taken summer trips. In the winter, I need to see how accurate the trips tab is, maybe I'll stick with 6%-10%, maybe I'll bump it up a bit... (I'm also on the east coast, and for the trips we take often, we often skip several SpCs, so I know if I see my buffer go way down, I can stop earlier)

One of the things that drives me nuts about the trip planner is that I can never seem to come in along the projected line. I am always below. I can take a 100 mile trip, average around 280 Wh/mi, but my "actual" line will be below the "projected" line on that graph every time. When the feature came out it was winter (and I was WAY below the line) and I assumed it would get better in the summer... but no. I am wondering if it is assuming I have a brand new battery pack when in reality I am seeing about 9% degradation at this point in my ownership.
 

Max*

Charging
Apr 8, 2015
6,672
3,719
NoVa
One of the things that drives me nuts about the trip planner is that I can never seem to come in along the projected line. I am always below. I can take a 100 mile trip, average around 280 Wh/mi, but my "actual" line will be below the "projected" line on that graph every time. When the feature came out it was winter (and I was WAY below the line) and I assumed it would get better in the summer... but no. I am wondering if it is assuming I have a brand new battery pack when in reality I am seeing about 9% degradation at this point in my ownership.

That is very odd. For my it's the opposite. I'm always above the line, doing 70-75mph. If I do the speed limit (55mph-65mph), I'd be WAY over the line.

Range mode on, AC at 67F, 4 people in the car (2 kids though) + stuff. It was warm though, probably 80F.

This weekend (skipped like 3 SpC along the way, was supposed to arrive at 0%, arrived at 7%, 200+miles). There were parts of the trip where my wife did some... "spirited" driving too, and still arrived with 7%.

20150904_231417.jpg
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,660
7,952
Boise, ID
Add to that the fact that all possible EV drama happens at the bottom of the battery, and I just don't go there.

Heh, yeah, I don’t ever want to be “that guy” who ran out of power, so I do leave margin and drive cautiously, so I don’t have to worry about it.
 

stevezzzz

R;SigS;P85D;SigX;S90D;XP100D;3LR;YLR
Nov 13, 2009
6,100
122
Colorado
One of the things that drives me nuts about the trip planner is that I can never seem to come in along the projected line. I am always below. I can take a 100 mile trip, average around 280 Wh/mi, but my "actual" line will be below the "projected" line on that graph every time. When the feature came out it was winter (and I was WAY below the line) and I assumed it would get better in the summer... but no. I am wondering if it is assuming I have a brand new battery pack when in reality I am seeing about 9% degradation at this point in my ownership.

That doesn't jibe with my experience in both the S85 and P85D: I consistently arrive with more range remaining than the trip planner estimated.

I voted 11%-15% buffer; it used to be 20% until I got comfortable with less.
 

mknox

Well-Known Member
Aug 7, 2012
10,103
1,870
Toronto, ON
That doesn't jibe with my experience in both the S85 and P85D: I consistently arrive with more range remaining than the trip planner estimated.

Beats me why it works that way on my car. I will often see myself trending below the line within the first mile or two. And I do not tend to drive fast or aggressively, and it does show in my very good Wh/mi numbers.
 

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