Electricity bill shocker

[dandelot]

Combining TED5000 and a bit of python code generating some Javascript and
one can get a nice report on the home network (I have apache2 web
server running
on one computer, no public visibility )

.
(I have a time of use plan, but the graph is simply use).
Neat way to keep an eye on electric usage.
Wife finds the graph meaningful.
Plus you can keep a permanent record with great detail. Data you
own and control. (TED has a RESTful interface available).
The standard TED web page (on a TED device on your home network)
is very nice and really useful for investigating
questions about what is costing what 'right now',
but my graph stuff gives a better overview. IMO. FWIW.

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Should have added: the problem with PG&E and Sunrun data is that it's
not available for the last few days, the data is always a few days behind.
Regrettably this TED (or other device) data is going to be very hard for many people
to install (even ignoring the cost) ... for renters and condo owners
for example.

We were pretty worried the PG&E Smartmeter would be reading wrong.
So far, AFAICT based on TED data, the meter is reading correctly.

 

[omarsultan]

I assumed 4 kWh/day vampire loss because the car consumes 1.5-2 kWh during first 12 hours. To represent day to day use you have to measure first 12 hours vampire loss and

4kWh/day seems to be too high for vampire losses:

1) As the car sits, it goes into progressively deeper states of sleep, so you cannot extrapolate the figures across 24hrs. If my car sits for a day, it maybe loses 2 miles of rated range max, so that is more in the less than 1kWh range, but....
2) You are double dipping the vampire losses. The car cannot be driving and experiencing vampire losses and charging all at the same time, so you cannot take vampire losses then multiply them out across 24 hrs then again by 60 days, since obviously, during that time, the car is being driven and charging.

 

[Matteo]

The car cannot be driving and experiencing vampire losses and charging all at the same time

Vampire loss happens because of battery thermal management and connectivity. Those happen all the time but any consumption that happens while the car is in drive mode counts towards Wh/mi numbers. Therefore I think half of what you said is correct. Drive time doesn't count but charge time does towards vampire loss. You just don't see it while charging but it happens.

1) As the car sits, it goes into progressively deeper states of sleep, so you cannot extrapolate the figures across 24hrs.

That's what I was trying to explain. Typically people park their car in the evening and start driving in the morning. There is maybe 12 hours idle time, but not longer. For deep sleep the car needs to be parked for longer which is not the case during day to day use. Therefore measurements taken when the car is parked at the airport or parked for 24 hours are inaccurate. Those don't represent day to day use.

If my car sits for a day, it maybe loses 2 miles of rated range max

Maybe settings or temperature has a big effect. Other people's experience have been different. Somebody said: "it had lost 11 miles range in only 13 hours. The air temp on arrival was 46." (Source) That's 20.3 rated miles in 24h which is 20.3rated miles * 75.9 kWh / 267 rated miles = 5.77 kWh/day. Another message says, "vampire loss went from 3 - 4 miles/day under 5.6, to THIRTEEN (13) MILES PER DAY" (Source)

 

[jerry33]

1800 sq.ft 1970s vintage house, DFW Texas

Typical day with Tesla only:

Typical day Tesla and Leaf (Note Clipper Creek not yet installed)

 

[omarsultan]

Vampire loss happens because of battery thermal management and connectivity. Those happen all the time but any consumption that happens while the car is in drive mode counts towards Wh/mi numbers. Therefore I think half of what you said is correct. Drive time doesn't count but charge time does towards vampire loss. You just don't see it while charging but it happens.

The car uses shore power for things like heating as long as its plugged, not that battery, and has done that for a while now. The 12V battery is the intermediary for most systems, not the main pack, so their drain is not a constant draw on the main pack, only when that car decides it needs to top off the 12V. Unless you are charging at 110V, any draw while the car is charging is going to get lost in the mix.

Maybe settings or temperature has a big effect. Other people's experience have been different. Somebody said: "it had lost 11 miles range in only 13 hours. The air temp on arrival was 46." (Source) That's 20.3 rated miles in 24h which is 20.3rated miles * 75.9 kWh / 267 rated miles = 5.77 kWh/day. Another message says, "vampire loss went from 3 - 4 miles/day under 5.6, to THIRTEEN (13) MILES PER DAY" (Source)

You have picked two outliers--hardly the way to establish a credible trend. The first was someone who parked their car in the winter, unplugged, for 10 days and the arrival temp was 30F not 46F. The forecast was 45F but the owner did not say what actual temps ended up being. The car did what it was supposed to. The second has no follow-up from the original post, but if losing 13 miles/day was typical, you can expect it to be a hot topic, it certainly was when the vampire losses were half of that.

 

[Matteo]

The car uses shore power for things like heating as long as its plugged, not that battery

I agree the car uses electricity from the charger when plugged in. The OP is measuring wall consumption for electricity bill calculations. Therefore the meter is turning regardless.

You have picked two outliers

I'm sure there are people here who have different meters for their Tesla or who have attached some device to measure the power used by the charger. Those people could easily calculate how much drive consumption they have (multiply mileage by Wh/mi) and deduct that from wall consumption. We both agree that charging losses are 8%. So let's find somebody who can provide more data and see which of us have better estimates. You said 1 kWh/day on average, I said 4 kWh/day on average.

The formula I would use is:
Vampire loss in kWh/day = (Wall consumption in kWh - (mileage * Wh/mi * 1.08 / 1000)) / days

* 1.08 : adds charging loss
/ 1000 : converts Wh to kWh

Example:
In 60 days somebody paid for 1730 kWh electricity for the Tesla. They drove 4000 miles and their efficiency was 350 Wh/mi. What is their vampire loss?
Vampire loss in kWh/day = (Wall consumption in kWh - (mileage * Wh/mi * 1.08 / 1000)) / 60 days
Vampire loss in kWh/day = (1730 kWh - (4000 mi * 350 Wh/mi * 1.08 / 1000)) / 60 days
Vampire loss in kWh/day = (1730 kWh - 1512 kWh) / 60 days = 218/60= 3.63 kWh/day

Any objections to this method?

 

[TaoJones]

When you consume 50% of a charge and have driven just 60 miles, the trip screen won't tell the whole story - it just reflects Wh/mile *while driving*.

For a more accurate reflection of efficiency, calculate miles driven versus % charged (miles from charge to charge versus (% * 3), for the sake of example).

Addenda: While the OP is concerned about the source of the "leak", in the end he's paying for electricity to get into the battery. How it's used from there may not be his concern - however, what's used is more than the sum of trip Wh/miles driven plus overnight vampire loss.

 

[sorka]

Ok, so I dug up last year's consumption numbers and it's 650 + 1200 kWh for those two months. Assuming the non-Tesla consumption did not change, the car is sucking up 2240kWh (4090-1850) for 4000 miles. Even if I get 200 miles per full charge, the car shouldn't be using 112kWh (2240 / (4000/200)). I do keep the car plugged in whenever I'm home but still.

Clearly something is wrong. Here are the possibilities (from impossible to most likely):

• Model S is not as efficient as claimed - impossible. I know there are losses involved in charging and vampire loss, etc. but it can't make that big of a difference. Besides, no one else is seeing such numbers.
• I drove much more than 4000 miles - unlikely. I probably drove a bit less than 4000 miles but rounded it up.
• My car charger/battery is defective - unlikely but will get TED 5000 to verify
• My AC or home insulation deteriorated since last year - possible
• My non-Tesla consumption changed vs last year - likely but need to investigate
• The meter is defective - possible

​
Anyway, I guess I need to get TED or something similar to monitor my usage. Any recommendations for a device preferably with an iOS app and remote access?

Thanks for the input everyone.

Can you look at your hourly usage and count only when you charge, how many kWh are reported by your car, and how many the utility reported you using during that exact period after subtracting your base usage.

In my case, when I charge in the middle of the night, before the charge starts and after the charge ends, I'm using 241 to 245 whats. So I can tell exactly how how much I used and exactly how much the Tesla said it got. I'm losing about 5% which is pretty darn good.

My electricity bill went down even though I'm driving 2000+ miles month because the EV-A rate gave me break on all of my electrical usage.

 

[RiverBrick]

If all you want is a generic "what's typical" answer, it is latent in the data the EPA publishes aside from the vampire drain: The original 85 kWh was rated at 265 miles range and 38 kWh/100 miles from the wall - meaning the EPA test aggregation showed 100.7 kWh from the wall.

What interesting is the newer cars show lower numbers - one of the reasons I'm still thinking the methodology changed somehow for the newer test on the AWD cars. The P85D is rated for 253 miles at 36 kWh/100 miles - meaning only 91 kWh from the wall. The 85D is rated for 270 miles at 34 kWh/100 miles - 91.8 kWh.
Walter

iirc, the EPA was charging at 30A, so if they finally got 40A service it could explain some of the efficiency gain.

 

[ev-now]

So if you take the 4,000 miles and assume 320wh/mi, then...

(((4000 * 320) / 1000 ) / 0.92) * 0.163458 = ~$227

(1) Sub in your actual wh/mi
(2) dividing by 1000 to convert to kW
(3) Dividing by 0.92 for normal efficiency losses

Meanwhile...

(4000 / 35) * 2.427 = ~$277

(1) Avg price of regular gas in NJ

Thanks for the formula. Subbing in what I saw for wh/mi while test driving, and my local rate (0.124 - yep CO is good for electricity, but not gas if you are still buying at 2.42!) - I find that the Model S is theoretically about 4 times more efficient than my horrendously inefficient '07 Tahoe ... so would be equivalent to 52mpg based on energy cost. 4:1 seems lower than I hear many owners claim, and there aren't many who are running less than 13mpg before getting their Model S surely.
Does 4:1 seem right to those here? The above seems pretty immutable (indeed I see it challenged as not including vampire loss, so this would push my ratio lower). That all said, gas dropped a long way, are my friends who claim 6:1 or more just remembering the 'glory days' when they'd moved over but gas was around or above 3.50??

 

[Armadillos]

Thanks for the formula. Subbing in what I saw for wh/mi while test driving, and my local rate (0.124 - yep CO is good for electricity, but not gas if you are still buying at 2.42!) - I find that the Model S is theoretically about 4 times more efficient than my horrendously inefficient '07 Tahoe ... so would be equivalent to 52mpg based on energy cost. 4:1 seems lower than I hear many owners claim, and there aren't many who are running less than 13mpg before getting their Model S surely.
Does 4:1 seem right to those here? The above seems pretty immutable (indeed I see it challenged as not including vampire loss, so this would push my ratio lower). That all said, gas dropped a long way, are my friends who claim 6:1 or more just remembering the 'glory days' when they'd moved over but gas was around or above 3.50??

What did you see for Wh/mi while test driving? I drive from Morrison, CO to Denver every day for work, and have some fun on the weekends. According to my car, over the 5,000 miles I've put on it, I'm averaging around 288Wh/mi.

Also, where are you seeing gas here in town at 2.42?

 

[m6bigdog]

Thanks for the formula. ...
That all said, gas dropped a long way, are my friends who claim 6:1 or more just remembering the 'glory days' when they'd moved over but gas was around or above 3.50??

The energy cost model (kWh vs $/gal) is a very valid comparison for EV vs ICE.

However, It is a case by case individual owner evaluation and you must use long term pricing and available options vs simply the current cost as the current price and options are subject to significant changes over the long period of vehicle use/ownership. I had my BMW 740i for 17 years before it was replaced with the MS.

That is the current cost only model may overlook the opportunity to take advantage of the other options available with EV ownership.
One of those is photovoltaic/solar electricity generation. This is an exclusive for the EV since I know of know way to totally offset the energy cost of an ICE'd vehicle; even biodiesel will pail in comparison.

In my case with 7.3kw/ac of solar panels I pay approximately $4/mo. for electric grid hookup and I have a credit at the end of the annual True-up period. Electrical kWh pricing for the EV-A rate is $.10 off peak, $.22 partial Peak & $.42 Peak periods so the electricity is not cheap!!
What does this all mean? Summer months $400 electric and monthly $175 ICE fuel bills gone...
I used 1779kWh's of electricity (A/C running all day with 70-72 deg,. inside temp) of which 1514kWh was solar generated in Jul 2015 and I still got a -$17 Net Metering credit for July. Now since I charged my Tesla at home all month for the 1250 miles driven and got a -$17 credit... then the mileage driven was better than free for the energy used and the EV MPG equivalent is infinite. Correct!!
Yep, the Solar system had an initial investment cost but that is recouped in 5-6 years (2.5 years left) and the Tesla cost more than the typical ICE's vehicle. However if I was in the market for another high-end ICE'd vehicle that's a wash and purchasing another ICE vehicle would not have allowed me to take advantage of the Solar generation already installed on my house to supplement the transportation energy cost.

IMHO, whether it be a Hybrid or High Mileage ICE, they are all soon to be the dinosaur of the personal transportation world and the EV is the future. Also, as EV technology topologies develop (range is the last big hurdle) the EV will quickly become more convenient, efficient and cost effective, but as you can see it is hard to beat an EV with +200 mile range, Superchargers & fee home charging that produce an infinite MPG that is my current situation with a MS...

 

[iadbound]

Maybe this well the OP:

I have a separate EV meter, and a very low cost per kWh for super off-peak charging (roughly $0.06 per kWh). In any event, looking at my March-July bills, in which I drove maybe 10,000 miles (very rough figure), I charged the car with 3,082 kWh of electricity and paid $190 for the period (I rounded to the nearest dollar). Seems like a heck of a bargain to me. FYI-- My lifetime watt-hour per mile figure is 306.

 

[ev-now]

What did you see for Wh/mi while test driving?

360-380 was what registered.

Also, where are you seeing gas here in town at 2.42?

That was fom the NJ post - gas here in Centennial 2.75ish.

 

[Vgsllc1]

My highest electric bill this year was under $150, and it's been pretty hot here in Texas.

Same here Jerry, my home is over 30 years old and we keep AC under 76 degree; with 100% home charging, the bill last month was $178 vs the month before $110. 1400 miles monthly.
In Texas the more khw we use the cheaper it gets.

 

[jcaspar]

Here in California I was able to get a separate EV meter. The rate is 0.06$ for off peak and off peak goes from 10pm to 4pm in the Winter. You should definitely check into something like this. My charges are about 16$ per month for the car, about 950 miles per month.

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In Texas the more khw we use the cheaper it gets.

You gotta love TEXAS!!