# Forums

## Rated Mileage vs how to calculate actual day to day mileage

On a full charge my car hits 269 rated miles, which i think is based on 300 Wh/mi, correct? If so can someone help calculate my actual useful miles based on my avg of 331 Wh/mi. I drive 62 miles round trip (up and down hills, some stop lights but mostly 72mph on cruise control) a day to work and have watched my avg Wh/mi fluctuate right around this 331. So if my full rated miles based on 300 Wh/mi is 269 miles. How far can I actually drive my car based on 331 Wh/mi (not counting the overnight drag / vampire loss)?

thanks

Alex K | September 26, 2013

300/331*269mi=244mi

Although the battery is 85kWh, you can't use all of it for driving, as the battery protects itself from complete discharge. Also, your car will display 0 range before it hits 265mi or 244 mi, but you will still be able to drive for a while and maybe hit the 265 or 244 mile range.

Rod and Barbara | September 26, 2013

In my experience a forecast rated mile is worth about 306 Wh and a decremented rated mile is worth about 287 Wh. This means, if you start with 269 rated miles, you can drive about 249 miles (306/331*269; very close to Alex K's prediction) before the car stop running. However, after driving about 233 miles (287/331*269) the rated miles remaining will read zero. I personally would never plan on driving the car past the zero rated miles point.

NICE | September 26, 2013

Actual range = watts avail (or batt size x % charged - 5% reserve) / average use for the trip (wh/mi.). For a fully charged 85kw x 95% / 331 wh/mi = 244 miles.

rajesh.bansal | January 12, 2014

I am analyzing 3 factors which determine thee ratio of actual miles to rated miles:
(1) Ambient temperature, (2) topological profile, i.e., how hilly / flat the terrain driven, and (3) Whether climate control - heating or cooling) is turned on. There is probably a 4th factor which is how many people/load one carries in the car, but for me that is not a variable.

My current date shows at an ambient temperature between 48 degrees and 53 degrees Fahrenheit, very modestly hilly terrain (Seattle/Bellevue area) and very intermittent climate control (primarily to defog, the ratio of actual miles to rated miles is about 75%.

EVTripPlanner | January 12, 2014

We have a route energy planning tool at http://evtripplanner.com/planner/1-0/ that is usually very accurate - it will tell you kWh for your route given temperature, payload, etc. accounting for hills and average speeds at the time the route is planned. There are also some charts and a spreadsheet that comes in handy at http://evtripplanner.com/calcs.php

With the most recent 5.x software, Tesla has changed the way the calculate Wh/mile, rated miles remaining and we haven't quite figured it out yet, but kWh used is most accurate. It also seems that they're holding closer to 10% in reserve (or have reduced the full charge voltage). I have 21k on my P85 after one year, and max range charge is about 251 miles now.

Charger | July 27, 2014

So if I use ev trip planner and it says I can go 256 rated miles at 339 Wh/mile and I drive slower and average less than 339 Wh/mile, say 310 Wh/mile. Does that mean my rated miles will be larger? I'm just a little confused on this.

Bighorn | July 27, 2014

@charger
Sounds like you're confusing rated miles with ideal miles, while evtripper estimates projected miles. 339Wh/m and 256 don't compute. A rated mile consumes 280 Wh, so driving at 339Wh/m efficiency would yield about 219 projected miles. Rated miles are a fixed commodity tied directly to the 280 Wh figure. Your projected miles can improve if you drive 310Wh/m. To complicate things, evtripper uses a 300Wh/m figure for their rated mile calculation, which is not what most people see with more recent firmware.

Charger | July 27, 2014

I'm even more confused now. I took the actual Wh/m and rated miles directly from evtripper.

Bighorn | July 27, 2014

Sorry--tell me your parameters and I'll try to figure it out.

Rated miles are different than what evtripper gives you. If you drive more conservatively, your projected miles will go up. You can put in a speed multiplier to prove the point with data.

sule | July 27, 2014

@Charger: "Rated miles" is a computed estimate based on current battery state and assumed consumption per mile, which is fixed at some 280 Wh/mi (a.k.a
"rated consumption").

Depending in conditions you may end up consuming more or less. Say going uphill, faster, against wind, through heavy rain, cold weather needing heating are some factors that increase consumption. If your (average) consumption is higher than rated (~280 Wh/mi) you will not be able to drive as far as "rated miles/range" indicates. If your consumption is double that, you'll only achieve half that range.

"Ideal" range and consumption are the same except are based on a different assumed consumption... one much harder to achieve.

EV Trip Planner may be "thinking" of 300 Wh/mi. That number is often mentioned and corresponds to the line on the energy graph. I suspect that, once upon a time, that may have been the number used for "rated" calculations but this is definitely no longer the case. I would like Tesla to adjust this and make them equal, either way.

Bighorn | July 27, 2014

Sorry, charger--I see I have confused the issue. I was wrongly assuming you were driving 256 miles. I just checked, and evtripper uses a different conversion factor for each of the 4 Model S configurations ranging from 280, 287, 292 and 300 Wh/m. My P 85+ does not jibe with the 300 number it is assigned, so rated mileage is not exactly predicted. If you can temper your speed, you will see increased efficiency in the form of reduced rated miles consumed.

centralvalley | July 27, 2014

To try to put range in perspective: I drove from the Blanding Supercharger to the Flagstaff Supercharger through Monument Valley.

This journey is 247 actual miles and 261 rated miles per EVTripper.

I max charged to 272 (on range mode) at Blanding. I kept my speed at about 57 (in a 65) for the first 155 miles or so, until I realized that I had more than enough buffer to travel at or slightly above the speed limit despite the sizable elevation gain the last 40 miles into Flagstaff.

I used 67.7 kWh for this leg at an average of 274 wh/mile. I arrived at Flagstaff with 32 rated miles remaining. I used 240 rated miles from the battery for 247 actual miles driven.

My actual wh/mile were slightly lower than the 286 used by the algorithm. Accordingly, I was able to arrive with a few more "rated miles" in the battery than had I maintained this 286 wh/mile constant. This probably saved about 2.95 kWh of juice.

Bighorn | July 27, 2014

@central valley
You'll see that you consumed 67.7kWh to use 240 rated miles which works out to your car's conversion factor of 282 Wh/RM--I suspect you were on version 5.9 or 5.11 because it appears to me that with 5.12, the conversion factor is even harder to achieve at 278Wh/m (at least on my P85).

Charger | July 27, 2014

ok I think I get it now. Thanks guys for the help. This forum has been a blessing for information!