# Forum

Unisciti allacomunità

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

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.

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.

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.

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%.

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.