# Forums

## Monthly bill?

Question for those of you who have had your car for at least a month now: how much extra are you paying for your electric bill now?

portia | December 26, 2012

it depends entirely on how much you drive, your electricity rate plan, etc.
I have not changed the plan to take advantage of the EV rate yet, so it is about 27 cents per kwh here in CA using PG&E on average,
at about 13 kwh more average per day, equates to \$3.5 per day, not a lot of miles.

you will be able to see total average wh/mile as you drive, so mine is about 350whm, people have reported their numbers on other threads here.
if I drive 100 miles per day, I would need to charge up 350x100=35000 wh or 35kwh more per day, then you just figure your electric rate and get your cost, (0.27x35=\$9.45) it works out pretty close to the electric bill. My equivalent gas cost would be around \$3.8per gallon at 20mpg = 3.8x5=\$19
or just use the calculator on the Tesla web site!

timdorr | December 26, 2012

I haven't had my car long enough to get my bill, but our rates are very low in GA (~5¢/kWh) so the impact is minimal. Also, once the Supercharger is installed nearby (I'm in Atlanta), I'll be able to charge for free :)

shs | December 26, 2012

With Solar and the EV rate, we will be paying 3.5 cents/kWh and since the E9A rate will also cut in half our cost of heating on winter nights, I expect our electricity bill to actually go down with a MS.

kalikgod | December 26, 2012

@kidalex

I have been driving my LEAF for 18 months and have almost 30k miles on it (20k miles a year). My electric bill is roughly \$30-\$40 more per month with a fixed rate of \$0.10/kWh. Figure the S will be about 10% worse than that.

Don't sweat the electricity costs...

jed-99aggie | December 26, 2012

This is a very interesting topic. Going from math theory to practice.

I have had my car only 2.5 weeks, however our utility provider has integrated their smart meters with online usage reporting (as recent as previous 24 hrs at midnight). So I have been trying to get a handle on what to expect. I addition to the simple math that is present in the cars usage data (e.g. Wh/mi) I am also reconciling the vampire load which I have observed at over 8 miles per 24 hrs on my car, as well as the charging efficiency. According to a calculation I did with 14 days of charging logged on the smart meter, I computed about 64% charging efficiently. This is comparing the incremental charging observed from our smart meter vs. the kWh consumed on our car since it's arrival. Granted I do not have a dedicated sub-meter, so I am attempting to net out the household's average daily consumption aside from the car's charging. (During this period weather has been rather nominal ~60 'ish.)

What shocks me is the observed waste from the vampire load (8miles*30 days= 240miles per month) that is one whole charge cycle alone; and resulting calculated charge efficiency. I understand Tesla to be working on the vampire load issue, I do have v4.0 installed from day 1. However if this trend is accurate many of the projections of operating cost per mile are understated.

Any of this observed by other owners (model S or roadster).

SpinMD in NC | December 26, 2012

Can you pls explain "vampire load"?
This is the first reference to it that I have seen...
Thx.

jed-99aggie | December 26, 2012

Vampire load = charge "leaking" from the battery. On standard charge our battery tops off at 242 miles of rated range. After sitting for 12 hours the rated range will show 238-237 miles.

Joyrider | December 26, 2012

Jed,
Are using the sleep mode?

jed-99aggie | December 26, 2012

Yes, sleep mode is turned on. Displays go to sleep upon departure from car.

Joyrider | December 26, 2012

Jed,
Are you using sleep mode?

Papafox | December 26, 2012

I'm figuring on using about 400 kWh /mo. with my Tesla because I have a long commute 5 days a week. Here in Hawaii electricity is very expensive at 33 cents/kWh, so that works about to be about \$132/mo. Right now I'm spending about \$160/mo. on gas for my very efficient Honda Civic, so I'd still see improvement. Alas, I installed enough solar panels on the roof (54) to take care of the large house, some air conditioning, the pool, and my long commute in the Tesla. After state and fed tax credits, the money I paid for Honda Civic gas plus the electricity bill will cover my solar loan, and after 5 years I can drive free for a long, long time.

sergiyz | December 27, 2012

PGE tier4 rate is 34cents/kWh in CA.
Note that once you're in tier4 you're paying these rates for *all* electricity, not just for charging your Tesla.
This is for the E1 rate.
They do have an E9 rate if you have an EV, but you really won't take advantage of that unless you install a separate meter, and that will cost you over \$200.
There's no delayed charging on Tesla just yet, and the off-peak rate for PGE is between midnight and 7am (if you're on E9 with a shared meter).
So, if you're in CA and your ICE car had about 30mpg (even less with today's gas prices), you're better off pouring Premium gas into your car than driving a Tesla S.
It only makes economical sense if you're staying in tier1 or tier2 pricing (regulated), and for that you really need solar.

sergiyz | December 27, 2012

@portia
You're assuming the charging efficiency is 100%, it's far below that (closer to 65%), meaning if you've spent 13kWh on driving you'll need ~20kWh to recharge.
My average over 2,500 miles is about 390Wh/mi, so 13kWh is just about 35 miles for me.
40kWh a day will put you solidly into PGE tier4 pricing within about ten days.
That's 40kWh a day total, not just an add-on.
End of the month you're looking at \$300-\$400 bill.
If you need a full charge (say you drove about 200 miles in one day), you're looking at about 140kWh to recharge.
The largest I've seen was 152kWh, that's almost half the PGE baseline (tier1-tier2 pricing) in a day...
So the math is far from being easy for EVs, especially in CA.

Mark29 | December 27, 2012

I have excess capacity from an array of solar PV at home (28 panels) and at the office (90 panels). Planning to drive on pure sunshine!

Brian H | December 27, 2012

jed;
"vampire load" has nothing to do with power "leaking". It is the power required to run devices that don't turn off when the car is not in use. Cutting down on it requires programming changes to switch off as many such devices as possible until needed. The "fix" TM is impementing should cut the miles/day loss down to about 2 from 8.

jed-99aggie | December 27, 2012

@Brian H. Thanks for the correction.

Yes there are systems that continue to function when you leave the vehicle, which are causing the drain on the battery. However, I understood v4.0 was to have reduced this effect. In fact the release notes state for "vehicle sleep" - "Note that keeping dilayed powered will reduce your car's range up to 8 miles per day..."

Was the vampire load greater before v4.0? If so what was the realized mileage lost per day for a stationary MS?

Flex | December 27, 2012

Had my S for two weeks so have not got a bill yet. However, I am in CA and use SCE for service. If you have a model S you need to look into some kind of time of use plan. I pay \$.16 per kWh in winter and \$.169 in summer for off peak use 6PM to 10AM. Peak rates are \$.18 in winter and \$.34 in summer.

Mike6 | December 27, 2012

PG&E has a great site for tracking your electric usage. Here is an image of my hourly usage from Dec 23. This was a full charge, starting at 12am. Cost: \$25.87 @\$0.30/kWh.

As you can see it took a full 7 hours to charge. Distance travelled was about 240mi.

PG&E hasn't converted me to the E-9A rate yet (currently I'm E1), which would take the \$0.30/kWh to \$0.19808/kWh.

It's simply a myth that you're going to get 3 cents per kWh with an electric car, unless you hardly drive it. While it is true that rates *start* for as little as 3 cents per kWh, the PGE baselines are really designed for household usage, not electric car usage. So you'll quickly find yourself way-over-baseline. I went over baseline in 10 days. So your average costs will be a little lower, but for the most part, even if you charge off peak after-midnight (which is hard to do because Tesla doesn't have a timer for starting charging - ahem!), your costs are more like 20cents/kWh than 3.

Overall, cost savings compared to gas is minimal. But, if you're owning a Tesla and excited about saving money on gas, you probably don't have very good financial planning skillz.

Here's the E-9A rates: http://www.pge.com/tariffs/tm2/pdf/ELEC_SCHEDS_E-9.pdf

Mike

David Trushin | December 27, 2012

I suppose it's called Vampire Load because in the middle of the night, the life blood of the car is mysteriously drained. Not enough to kill the car, but enough to make it's owner feel rotten. Have you tried a circle of garlic around the car while it's in the garage?

Mike6 | December 27, 2012

@sergiyz -

I basically agree with what you're saying. But the numbers you've cited are a bit different than my experience. I've got 2200 mi on my tesla, and I drive about 100mi/day.

For 100mi, I consistently use about 29-33kW of charge. and recharging is between 3.75 and 4.5hrs @9600W/h.

So if I charge after midnight, that is a cost of \$7.20 to \$8.64 per 100mi.

If I drove a car with 40mpg, that would be 2.5g of gas, @\$3.50/gal, that's \$8.75.

Overall - with nighttime charging and over-baseline rates, electric and gas are about a wash.

But - if I ever have to charge during the day, prices get astronomical! Over-baseline rates for E-9A is \$0.54/kWh, driving the cost of the Tesla to \$23 - 3.5 times more expensive than a 40mpg car, and about the same cost as a 15mpg car.

Mike

Mike6 | December 27, 2012

I forgot to callout the inefficiency of charging, which @sergiyz also pointed out.

While I only consume ~30kW of charge each day, it takes ~40kW of electricity to charge it back up in the morning.

This is a subtle but important part of electric consumption which seems to be omitted from EV marketing materials.

Not complaining - love my Tesla. I never expected to save money with this car, and I don't. But if you're thinking you will, you're kidding yourself.

Mike

shs | December 27, 2012

One of the real advantages of having solar is that we are always within the baseline rates. In our case, since we have electric (geothermal) heating (no gas or propane in the house) we are considered an all-electric house and the number of baseline kWhs is increased over a house where you use propane or natural gas for heat. Even in the winter our 7.2 kW solar panels produce enough juice in any month to keep us within baseline. With the E9A rate (single meter), the after midnight rates are 3.5 cents/kWh which will allow not only low cost charging, but heating as well. So for us the E9A rate is a no brainer. On the other hand, we have a friend right down the hill, about 3000 ft lower in elevation, and for him, the major electrical cost is summer cooling not winter heating, and the E9A rate wouldn’t help at all. So it all depends.

sergiyz | December 27, 2012

@Mike6

What is your average Wh/mi over the whole 2,200 miles if you don't mind sharing that ?

I didn't expect to save driving a Tesla either, was just a bit surprised by how much the advertised numbers were off comparing to real life numbers, e.g. 92% charging efficiency stated in specs (granted, they say "maximum efficiency") is nowhere near that, off by about 30%; the 300 mile range that changed into ~260 EPA rated and closer to 200 miles real on a standard charge etc.
I'd say unless you live in a state with really cheap electricity or unless you have a supercharger in close proximity, you should consider installing a PV system before you get your car.

JZ13 | December 27, 2012

The car I'm replacing is a Mercedes CLS63 that gets 14 mpg and needs 91 octane fuel. The Tesla calculator says that at 15k miles per year, I should save about \$3,500/year if I charge the car at midnight. Plus I won't need anymore expensive Mercedes oil changes, etc.

sergiyz | December 27, 2012

@jz13
Take this calculator with a (large) grain of salt.
Tesla maintenance is \$600 a year, although they still haven't sent any paperwork for that (one time or a pre-paid plan).

timdorr | December 27, 2012

@jed-99aggie

While the displays are shutting off, when you come back to your car after a notable amount of time (such as when you come back to it in the morning for the first time) do the silver Tesla logos show up on the dash and center displays? That indicates the displays are booting back up after being powered off in deep sleep mode.

If they are coming back on instantly, that means your displays are not deep sleeping and 8 miles/day of loss is to be expected. And if that's the case, I would contact Tesla about it. While vampire load can be seen, it shouldn't be that high.

jat | December 27, 2012

@Mike6 - the overall charging efficiency of my LEAF, as measured by the power at the breaker box compared to what the car says it received (and seems to match based on usage) is about 87%. I would expect the Model S to be similar to that rather than the quoted 65% (the specs say 92%, but that may only include the charger in the car and not the HPWC/mobile connector).

Also, not everyone has such high electric rates. In Georgia, the standard electric rates in the highest tier are \$.04419/kWh except for the summer, when it is \$.09126/kWh. There is also an EV rate, which drops the rate to \$.0129/kWh midnight-7am, but it raises the summer peak rate to \$.199951/kWh which would cost me much more on powering the rest of the house would dwarf the savings on charging the cars. I currently spend about \$26/mo in the summer and \$14/mo charging my LEAF, driving about 800mi/mo -- so it doesn't take much to dwarf that cost.

http://www.georgiapower.com/pricing/residential/

iholtzman | December 27, 2012

I live in the Chicago area. Com Ed is our electric provider. IL is deregulated so we can shop for power. My round the clock fixed rate is only .048 add delivery and taxes and we are about 7.5 cents per kWh all in. If you do not live in deregulated state talk to your elected officials. The rates you guys are paying in CA are outrageous!

Ira

DTsea | December 27, 2012

iholtzman has it right. If you unlucky California residents could squash the NIMBY problem, so that power plants could be built in your state, the rates should not be so high. Buying all your power across state lines, costs a lot more.
Seattle has its own hydroelectric power station. .09/kWh.

Brian H | December 28, 2012

Like in Chicago, here in BC. Most hydro is electric, and rates are about 7.5¢/kWh 24/7, 365. So 100 miles costs about \$2.50, or 2½¢/mi. For a 30 mpg car, that's about 3.3 gallons, which (using USGal) costs about \$5/gal here, so about \$16.50 per 100 mi., or 16½¢/mi.

The savings on fuel is thus 14¢/mi. Drive 20,000 miles to save \$2,800.

jed-99aggie | December 28, 2012

@timdorr

Thanks for the astute observation and very helpful comments. I took note (& video) this morning upon approach and entry to the vehicle. It had been sitting for at least 10~12 hours. When the door was opened the displays came right on, no intermittent Tesla "T" screen.

I did recon firm that I had correctly set the display option in the menu to turn displays off.

On the other hand, the good news is that the car indicated it was ready for a SW update. So I decided to proceed and see if that resolves the vampire load problem.

This being the first SW update, I could not see any specifics about the release version queued for the update. To other experienced owners, is this shown somewhere in the update pending/notification screen?

dtesla | January 27, 2013

I've had my MS for almost 3 weeks now. My MS tells me it us using 430 Wh/mile. (Lots of battery and cabin heating needed.) But my utility power meter is telling me it's closer to 800 Wh/mile.

What are other people experiencing?

olanmills | January 29, 2013

I get pretty nice rates in WA. I figured it costs me about \$6/week in electricity to drive the Model S. I used to spend \$50 a week on gas.

Mark22 | January 29, 2013

@dtesla, it really depends upon the amount of driving you do, when you charge and drive and what temperature the battery pack is at.
The car will warm or cool the pack as necessary while charging for the best long term health of the batteries. This draws extra power.
So if you drive 5 miles, park it in your garage all day in cold weather and then charge it overnight, you will use power to warm up the battery, and then charging the car. Say the heater needs 5kWh and the mileage requires 4kWh. You would only have 42% efficiency. On the other hand, if you drove 150 miles and the batteries needed 60 kWh, but still needed 5kWh for heating, your efficiency would jump up into the 80% range.

I, in Minnesota get a charger efficiency ranging from 50% to 85%. In the late spring I expect that to climb to 70% to 92%, but we shall see.
One thing for sure, driving electric has given me another reason to really hate winter;-)

andykeller | January 30, 2013

I'm buying a home in northern indiana and was pretty excited to see this:

http://www.nipsco.com/en/our-services/in-charge-ev/in-charge-at-home.aspx

Of course once I called them to setup service, I found that they're not my electric provider. Free installation and overnight charging is a sweet deal. The program is in effect until January 31, 2015, and is limited to 250 customers, or until funding is exhausted.

Epley | January 30, 2013

I have been spending around \$35 per month to charge. Compared to almost 3 times that in gas...