Battery losing 1 mile per hour when parked

Battery losing 1 mile per hour when parked

I searched the forum and cannot find a discussion that matches this one so here goes:

I have had my Model S for just over two weeks now and it consistently loses 1 mile of range per hour when it is not plugged in. Considering that at full charge it is rated for 188 miles that is a 12.8% loss per day. At this rate of loss my car would be at zero miles in less than eight days. The owners manual says that the loss of range should be around 1% per day. When I called the Tesla service representative I was told that 1 mile per hour loss was normal and not to worry.

I am curious what losses other people are seeing. If there is already a discussion with this information I would appreciate being pointed to it.

DanD | February 11, 2013

there is a thread that I started about losing charge while parked at Philly Airport.

It's got the explanations Tesla customer service has given.

David59 | February 11, 2013

Which thread is that, exactly?

Hans (Amsterdam) | February 11, 2013

I guess that when it loses 1 mile of range per hour when it is not plugged, it loses 1 mile per hour as well when it IS plugged in (on-board systems need energy all the time). So in one year your will loose 365 x 24 = 8.760 miles. This seems like a lot, not to worry ?

I have been driving a Nissan Leaf for almost 2 years now, and it didn't loose miles when not plugged in, simply because it was switched off.

Also I have a couple of Lithium Batteries (total 8 kWh) at SOC of 40% doing nothing now for almost 4 months. Energy loss after 4 months was near to zero, simply because they were switched off.

L8MDL | February 11, 2013

Airport thread:

Pay NO attention to the title - it's pure hyperbole, IMHO...

David59 | February 11, 2013

I read through the Philly Airport thread from start to finish. It sounds as if the loss slows down after a while, something like a logarithmic curve. This does not address my main question, however, which is what is "normal"? If the Tesla manual says 1% per day and I am getting almost 13 times that loss, how is this considered normal? What are other Tesla owners seeing with their cars?

Jolinar | February 11, 2013

yea, I am also very concerned about losing charge during the day especially when Model S Facts page ( says exactly:
"The Model S battery will not lose a significant amount of charge when parked for long periods of time. For example, Model S owners can park at the airport for extended vacations without plugging in."
And if I remember correct owners manual says something about 1% lose per day, not 1 mile per hour.
Tesla should do some official statement about that...

DanD | February 11, 2013

The loss does appear to be logarithmic. Sort of. But I can't be sure. They are telling me 4-5% a day in charge. But the mileage loss is different.

The experience very much makes me think that cold weather has surprised the California design team.

Roadside Experience was shocked to learn that Philadelphia Intl. didn't have charging stations.

Welcome to the Northeast.

When I parked the car it said I had 140 miles to go. That was Thursday. 4 days later it tells me I have 74. I've got a 45 mile drive back home.

mal42north | February 11, 2013

Hopefully this is something that will be addressed when sleep mode is re-enabled. On the bright side, the monthly electricity savings will probably pay for the 3G data plan.

jat | February 11, 2013

I think looking at the projected range is conflating the actual state of charge in the battery with the projections of how many miles can be obtained from that charge. Tesla has already acknowledged that the calculations on range take into account how much energy can be extracted from the battery at its current temperature, and do not take into account the fact that the battery will warm up from being used.

A more useful value would be the battery_level field in the charge_state API used by the mobile app (unfortunately you can't get that easily without writing code yourself at the moment), which should be just the battery's state of charge.

sergiyz | February 11, 2013

You can switch from miles to kwh, that should be more accurate.

nickjhowe | February 11, 2013

Though frustrating, I wouldn't be too worried. When they issued Software Version 4.0, loss dropped to 3-4 miles per day when not plugged in by using what TM calls 'sleep mode'. There were concerns that under certain scenarios the car might not come out of sleep mode 'gracefully' and so it was pulled in the 4.2 release. Based on conversations with TM it is definitely coming back; the only question is whether it will be days, weeks or months before it reappears.

July10Models | February 11, 2013

Usually on the drive home from work averaging about 400kWh/mi the battery recovers about 15 miles of ideal range from a cold start, sub freezing temperatures. I use 5 miles of range for a 20 mile trip. Of course I wouldn't set out on a 100mi trek with a cold battery showing 85mi left. We will still have to deal with this uncertainty in cold weather specially after deep sleep is re-enabled. It is just a fact of life with cold Li-ion chemistry.

Brian H | February 11, 2013

Get the ideal range and divide by 3. That's your SOC. Honest.

Brian H | February 11, 2013

Oh, not quite. I forgot the ideal changed to max 265. So, ideal range divided by 3, plus about 1/8. Pretty close. E.g.: If ideal shows 210 miles, you're at 70+9= 79% charge. If ideal shows 90 miles, you're at 30+4=34%. To the nearest 1%.

Klaus | February 11, 2013

Seems to me that if you need to leave your S unplugged for an extended period, you could power the car off. That is what I was told the transport people are supposed to do after loading up the cars for transport across the country.

jat | February 11, 2013

@BrianH - ideal didn't change to 265, that is rated range. However, it isn't as simple as dividing since the software takes into account the battery temperature to calculate the range. So, you only get the battery capacity if the temperature was unchanged, not the capacity after it warmed up to normal operating temperature.

Brian H | February 11, 2013

In that case, it's even simpler. SOC = Ideal/3. No calculation is done on ideal range to speak of, AFAIK. 300 miles = 100%. 210 miles = 70%. 60 miles = 20%. etc.

Brian H | February 11, 2013

Above for the 85kWh, of course.

Scwins | February 12, 2013

I charged last night on Standard mode to 190mi and charging self quit.
That charge ended about 9:45pm.

When I came out to the car in the morning, that same 190mi indication had dropped to 183mi. So I lost 7 miles overnight.

This seems like a lot to me. Any thoughts? It's realy just uder .5% but on line for about 1% for the day.

David59 | February 12, 2013

I don't know how you get 0.5%. If by over night you mean about 8 hours then that is about 7/8th of a mile per hour. In 24 hours that would be 21 miles, or 11% per day.

Hills | February 12, 2013

7/190 = 3.7%, and over how many hours?
I lose 8 ish miles over 10-12 hours starting at 240 rated miles.

queni | February 12, 2013

Had ours parked for 14 days, unplugged.......started 195 mi and ended up with 66 mi left. In CA so were lucky to have good weather in the day time and lows around 30's at night.

mbcaffe | February 13, 2013

I left my car plugged in for the weekend and it went from 190 to 182(or so) and then back up and then back down. I think the best bet is to follow the instructions and leave it plugged in (if possible).Hopefully a software update with either the sleep mode or charging scheduler or both would be nice. In the meantime, if your daily range allows it, just drive the hell out of it and enjoy the ride.

nickjhowe | February 23, 2013

See this post for my results parked at Miami airport (70's during day, 50's over night). Net-net: settled down to c. 0.4 miles/hour after first 12 hours.

alan | February 23, 2013

I'll preface this by saying I love the car. But the operating costs are much higher than implied / advertised. For example: Last weekend (President's Day) I went away for four days, left the car unplugged in my driveway with about 90 miles of range per the dashboard (rated range). When I came back (96 hours later) the car indicated 10 miles of range left, so that's 80 miles of range depleted in 96 hours, or just under 1 mile of range for every hour unplugged. That was in Berkeley with highs probably in the 50s / 60s, and lows last weekend in the low 40s. That's much higher than what was expected (the 1% per day, or about 3 miles per day of rated range - really it's 6x higher!).

I think Tesla needs to do a much better job explaining the details. It's an awesome care, but...

If it truly depletes at 20 miles per day, at my actual energy usage of 350 Wh/mile that's a consumption of 7kWh / day to go nowhere. At my *real* weighted average cost of electricity (PG&E E-6 rate, time of day metering) which is between $0.24 and $0.32 per kWh, it will cost me between $1.68 and $2.24 per day. Doesn't sound like much, but x 365 = $817 per year just to park in the driveway.

nickjhowe | February 23, 2013

This will get fixed as soon as TM puts sleep mode back into the car. Hopefully in 4.3 Should be down to 2-3 miles per day.

dschulner | February 23, 2013

Call service. I leave my car unplugged every night. The loss of miles is completely negligible. I don't even notice. Plug in once maybe twice a week.

nickjhowe | February 23, 2013

@dschulner - which s/w version do you have? I assume not 4.2?

prash.saka | March 5, 2013

Bump. Does anyone have any new information?

EVTripPlanner | March 5, 2013

My experience has been that in moderate weather, the average parasitic losses when not driving are about 13-15 rated miles/day. That comes out to about 180 watts. Powering down does not seem to help much. I suspect software updates will reduce that amount over time (and that a recent update might have made things worse). Also: when the battery gets down to a lower level, the car is supposed to go into "deep sleep mode" - see

I have done calculations on monthly and by-the-mile fuel costs at - here is a snapshot (you can make your own adjustments if you download the spreadsheet):

EVTripPlanner | March 5, 2013

Oops - posted wrong table above - here is the one with Electricity Costs:

DouglasR | March 5, 2013


You say that the parasitic losses should equal about 180 watts. Wouldn't those losses normally be measured in kWh? And for 14 rated miles at 308 w-h/m, the losses would be about 4.3 kWh, not 180 watt-hours.

Also, your input chart shows maximum charging at 20 kW. You might want to point out that this is with twin chargers. Most people have a single charger, which charges at half that rate.

EVTripPlanner | March 5, 2013

Watts is *rate* of loss. kWh is *total* over a specified time period. If you run a 100 watt light bulb for 10 hours it uses 1kWh...and that is what you pay for!

So, applied to MS, the 180 watt parasitic load x 24 hours would be about 4.3 kWh - but that would double-count the "baseline" draw when driving. My calculations use non-driving time and estimated total of 123 kWh per month (never used 180 as total energy, just went into the calculation). Thanks for double checking!

True about charger max kW - only an issue for the HPC...home NEMA 14-50 is still under 10kW.

DouglasR | March 5, 2013

Yep, you're right! :)

Brian H | March 5, 2013

... sleep ... sleep... must sleep ....zzzzzzzzzzzzzz

jemartin | March 5, 2013

@Cliff - Great data. Thanks.

I've been trying to quantify the parasitic loss as well. I put a pair of power clamps in my breaker box directly on the two hot leads that go to the nema 14-50 in my garage. I'm able to track the kWh I put into the car on an hourly basis. I plugged in the 180W parasitic loss power that you derived, but I'm getting a smaller difference between kWh supplied and kWh driven than I expected. For instance, I took an odometer and kWh reading on 3/2 8am from the car. I did the same on 3/5 7am. The car says I drove 82 miles and used up 27.6 kWh driving (336 Wh/mile). The power meter in the breaker box says that I supplied 41.7 kWh. Assuming that the car was idle 23h/day, at 180 Wh, parasitic loss would be 12.2 kWh. So if the car had no parasitic loss at all, I would have supplied 41.7 kWh - 12.2 kWh = 29.5 kWh. This means a charging efficiency of 93%. So either the car is overestimating kWh driven, or the 180 W parasitic loss is closer to 140 W. The power meter I'm using is pretty accurate as far as I can tell. I've repeated these samplings 3 different times and I find the same outcome. I have a 85kWh model (rev 4.2) and I top it off every day at 240v 40A.

EVTripPlanner | March 5, 2013

@jemarting - Depending on temperature/trend, I wouldn't be surprised if the parasitic could be as low as 140W - my measurements varied A LOT (I have one set of measurements on the spreadsheet at the URL above). You also can't count on the Rated Range being altogether accurate - and then there is the temperature-adjusted Rated Range. If you start your measurement when the battery is cold, it is artificially low.

prash.saka | March 7, 2013

Cliff, thanks for the numbers. A loss of 13 - 15 miles per day isn't that bad.

But for mine, I noticed that, in just over 1 hour, there was a 5 loss of 5 miles. And in two hours, there was a loss of 8 miles. This was when the temperature was around 35 degrees. I will keep track of how much these losses are over a period of time.

Brian H | March 7, 2013

If the car was just sitting cooling, that may not be real. Just reporting what the chilled output would be if the battery didn't warm, which it necessarily would. It's an anomaly TM is working on.

GregZw | March 8, 2013

I have been keeping a log for the past week and I am losing about a mile of range every 2 hours while parked.

I typically drive 40 miles a day. During the 24 hour period my miles remaining will go from 190 (standard charge) to about 130.

I have concluded that I get about two thirds of the range indicated by the miles remaining. Temp has been in the 40 - 70 degree range.

I am on v4.2 of the firmware.

My electricity cost with TXU is 12 cents per KWH. To charge from 0 to 230 range should take 60KWH and cost $7.20 and I should get actual milage of 153 miles. So my cost per mile is about 4.7 cents per mile. My previous car (Infinity M35) got 17.5 miles per gallon at $3.50/gallon for premium or 20 cents per mile. I am currently saving $185/month for fuel.