High cost of charging according to TeslaFi?

[howardnj]

I can see how some people would only be interested in how much energy the car is using while moving. But I'm trying to evaluate total cost of energy consumed to own my car. The car may be super efficient while driving but if it costs an arm and a leg to charge it and keep the battery warm while idle or sleeping then it's not really as cost effective as it is on paper. A significant expense isn't being discussed (assuming TeslaFi is right and my math is sound).

I'm not sure why you're comparing to ICE cars. I own a Model Y, you don't need to convince me of the virtues of electric vs ICE. I'm simply trying to figure out how much my MY is costing me in energy costs. And there's a cost that I wasn't anticipating because I was only focused on energy consumed while driving.

myisking
FWIW I closely track my expenses and MPG with my present 2016 Infiniti Q70.
I went back to my spreadsheet to track how much I spent in gasoline over the most recent 3685 mile period.
My total spent on gasoline was $580.24.
So it appears that the cost of running and charging an EV is much less.
My EDD was moved up today from July 2022 to June 22

 

[charlesoris]

I don't think my actual rate is too relevant for everyone else here. The point I want to drive home is owners often think about their MY as costing them 260 Wh/Mile, or 241 Wh/Mile in their M3. I think part of this comes from the Tesla Energy dash display where it shows your drive efficiency and owners are comparing that to the rated Wh/Mile. This is fine for driving efficiency but then that number is often used to translate it to a direct cost for the trip. Most posts or blogs talk about a trip costing them $x based on just that drive efficiency. Some even use that number and compare it to gas costs for ICE cars over those same miles which would is not a direct comparison.

The reality is it costs me closer to 366 Wh/Mile or really 422 Wh/Mile (when charging efficiency is taken into account) on my MY when taking into account charging and driving costs (despite a solid diving efficiency of 262 Wh/Mile). This is 41% or 62% more expensive in energy costs to charge and drive those miles than rated. If you don't pay for charging your car it's less relevant and only focusing on driving efficiency makes sense. For those that do (most of us) and are cost conscious, that number - "How much did my Tesla cost me on my electric bill to charge my car and drive those miles" - is something to be considered.

People report about Tesla making tweaks to improve the driving efficiency Wh/Mile. There is less talk about and improving efficiency of charging / sentry mode / pre-conditioning / keeping the battery warm / etc which based on my observation can have a huge impact on cost of ownership.

To answer your question directly, I pay .18 per kWh in NJ. It's not a great rate (but don't tell the unfortunate folks in CA I said that). After looking over my math, I'm looking to see if I can reduce my supply costs. My delivery costs are fixed at .05 per kWh.

I agree with your concerns. I am from California and with the gas and electricity costs on the rise, I, too, am very concerned.

 

[rrolsbe]

We are on an EV TOU plan here in northern Nevada. The EV rate from 10PM to 8AM (10 hours) is approx 6 cents/KWH TTL. I do not include the $15.25 meter charge in my calculations because you pay that even if you used no electric in a given month. AFAIK, many electric providers have additional charges that can add up to the quoted KWH rate. So if I drove my LR Model 3 240 miles per day (that's a LOT) my home charging cost would be around (60KWH X 0.06/KWH) or $3.60. Lets call it $4.50 average worst case to account for all home/car charging related costs. To drive an ICE car that gets 25MPG that same 240 miles, given the current fuels costs of around $3.75/gal and required scheduled maintenance costs per mile, would cost more that $37.50 (so over about 8 times as much)! Now if you compared my charging costs to cars like a Toyota Prius or Corolla, it would not be an 8 times savings but that is like comparing apples to oranges.

 

[Madsen203]

I agree with your concerns. I am from California and with the gas and electricity costs on the rise, I, too, am very concerned.

Relieve your concerns and get solar. TOU-B plan is cost effective w solar if you max it out.

Check out solar install group (SIG). They are about $1k per panel but may be less now (before rebate). If I were to do it again, I might get Tesla solar just for the power wall and rebates associated with that. Emphase power walls aren’t bad option though.

 

[charlesoris]

Relieve your concerns and get solar. TOU-B plan is cost effective w solar if you max it out.

Check out solar install group (SIG). They are about $1k per panel but may be less now (before rebate). If I were to do it again, I might get Tesla solar just for the power wall and rebates associated with that. Emphase power walls aren’t bad option though.

TOU-B plans were discontinued by SCE. TOU-D-PRIME seems to be the cheapest, although there are a few of us at home during peak hours.

 

[Madsen203]

TOU-B plans were discontinued by SCE. TOU-D-PRIME seems to be the cheapest, although there are a few of us at home during peak hours.

They were trying to push PGE customers to this. The cost delta is huge! For every 2kwh generated in solar, translates to one hour used during peak time. That sucks!

 

[NovaTech]

I got my first electric bill with a full month's charging included. It's been colder than normal in NoVA, and so we're using more energy than in December when it was pretty mild for the most part, but my monthly energy cost for charging my MYP is ~$65 using my Gen3 Tesla charger. I leave my house with 90% battery and typically get home with about 73% (it's been cold). 40mi round trip to work and back each day. I plug in when I get home, charge overnight, wash and repeat for M-F. I am mildly disappointed with the cost to charge. I also have a pool, and running that equipment isn't much more..

 

[charlesoris]

I got my first electric bill with a full month's charging included. It's been colder than normal in NoVA, and so we're using more energy than in December when it was pretty mild for the most part, but my monthly energy cost for charging my MYP is ~$65 using my Gen3 Tesla charger. I leave my house with 90% battery and typically get home with about 73% (it's been cold). 40mi round trip to work and back each day. I plug in when I get home, charge overnight, wash and repeat for M-F. I am mildly disappointed with the cost to charge. I also have a pool, and running that equipment isn't much more..

Something doesn't make sense. You commute about 200 miles a week and roughly 860 miles a month which costs you $65.00. That gets you 13.2 miles per dollar or $.07 per mile. Compare it to an ICE vehicle that gets 30mpg and $4.50/gallon which would have cost you $129/mo: 6.6 miles per dollar or $.11 per mile.

 

[NovaTech]

Something doesn't make sense. You commute about 200 miles a week and roughly 860 miles a month which costs you $65.00. That gets you 13.2 miles per dollar or $.07 per mile. Compare it to an ICE vehicle that gets 30mpg and $4.50/gallon which would have cost you $129/mo: 6.6 miles per dollar or $.11 per mile.

Yeah, I thought the same and need to do some additional, better, measurements and calculations based on actual usage. I really wasn't thinking I would need to, but the difference in my electricity bill was more than expected.

 

[Z_Lynx]

Since I got my car and observed unexplained usage patterns, I also wondered what the actual energy use would be.

For what it's worth:

4 month average 2020 model Y is 0.3kwh/mi. Costs me 3 1/2 cents per mile. Car claims usage of appr. 0.25 kwh/mi

• Location: Central Virginia
• Where charge: home
• Charge rate: 20A 240V to max of 75% capacity
• Avg trip: 30mi
• Electric rate: ~11.5 cents/kwh flat rate
• Always plugged in?: yes, winter; no, warmer weather
• Source: TezLab: [using actual kwh drawn, not kwh added]
• Possible sources of error: a few but not likely all mini-charging sessions recorded and some failed reporting from TezLab.

Last night 19 degrees, do not believe electricity was drawn to heat battery based on house and car usage (no driving, 4-5kwh/24hrs for whole house).
Seldom preheat. Am known to open windows on hot days (hot days not included in sample, would increase kwh/mi).

 

[Mrbrock]

Yeah, I thought the same and need to do some additional, better, measurements and calculations based on actual usage. I really wasn't thinking I would need to, but the difference in my electricity bill was more than expected.

What were you expecting cost wise? Cold will decrease range and increase costs. If you are charging right when you plug in vs scheduling departure you are missing out on regen driving on a cold battery. Would be worthwhile switching to scheduled departure to see if that reduces energy needed by starting with a warm battery. Z_lynx is reporting less than half your cost.

How did you get to the $65 amount? 40 miles and 17% equates to a 235 mile range at 100%. 235 vs 326 is considerably less but not out of range for cold weather. Even so, 17% of 78 kwh is 13.26 kwh or 331 wh/mile. 331 x 860 = 285 kwh. $65/285 = $0.23/kwh. Is this your rate? If your rate is closer to Lynx's then you have something mistaken in your $65 calculation or you have some huge charging inefficiencies with your Gen 3 or you are doing preconditioning or something that is using a lot of idle power (sentry mode?).

 

[NovaTech]

Since I got my car and observed unexplained usage patterns, I also wondered what the actual energy use would be.

For what it's worth:

4 month average 2020 model Y is 0.3kwh/mi. Costs me 3 1/2 cents per mile. Car claims usage of appr. 0.25 kwh/mi

• Location: Central Virginia
• Where charge: home
• Charge rate: 20A 240V to max of 75% capacity
• Avg trip: 30mi
• Electric rate: ~11.5 cents/kwh flat rate
• Always plugged in?: yes, winter; no, warmer weather
• Source: TezLab: [using actual kwh drawn, not kwh added]
• Possible sources of error: a few but not likely all mini-charging sessions recorded and some failed reporting from TezLab.

Last night 19 degrees, do not believe electricity was drawn to heat battery based on house and car usage (no driving, 4-5kwh/24hrs for whole house).
Seldom preheat. Am known to open windows on hot days (hot days not included in sample, would increase kwh/mi).

Is there a cost difference of charging at 48A vs. 20A? I've got my Gen 3 charger set to 48A, but I could dial it back. I just assumed there was little to no difference given the time to charge at one rate vs. another. Either way, I'm not going to perform any calculations until I get my next statement.

 

[Z_Lynx]

It is only through TezLab I have a report of kwh added vs. kwh drawn, yielding an efficiency percentage. I imagine other platforms might have something like this accessible? You would want to look at efficiency of 48A vs. 20A (or whatever you choose as your charging rate):

I think the big inefficiencies come when trying to charge at 120V, 20A. The car and monitoring equipment are used more. Supposedly high rates of charge (Superchargers) can be tough on the batteries.

My 20A is due to what I easily had available (unused baseboard heating from 40 years ago). Added a ground fault breaker and an exterior protected outlet (wood frame house).

Because the efficiency I see reported varies from charge to charge, it is not as easy to compare by simply manipulating the charge rate. You can set up your app to let you know start and finish times and perhaps compare how long it takes to reach your preset endpoint at a particular rate. Easier with the TezLab app.

Hot summer days will have somewhat lower efficiency for all methods of charging due to fans running to dissipate condensate in the cooling system and avoid bacterial growth.

 

[DanDi58]

Because the efficiency I see reported varies from charge to charge, it is not as easy to compare by simply manipulating the charge rate. You can set up your app to let you know start and finish times and perhaps compare how long it takes to reach your preset endpoint at a particular rate. Easier with the TezLab app.

I just randomly looked at 2 charging dates - Feb 1 (7.5kWh drawn, 7.1 kWh added) and August 19 (38.5 drawn, 35.4 added). I would have thought that the warmer weather would have meant a higher efficiency. But perhaps the efficiency goes down the more power you are drawing....?

 

[Mrbrock]

I just randomly looked at 2 charging dates - Feb 1 (7.5kWh drawn, 7.1 kWh added) and August 19 (38.5 drawn, 35.4 added). I would have thought that the warmer weather would have meant a higher efficiency. But perhaps the efficiency goes down the more power you are drawing....?

Higher temps require more cooling.

 

[Z_Lynx]

In the winter, if you charge immediately on return (and don't have to worry about time of charge), the battery is preheated and perhaps more efficient. Summer, maybe even has to cool the battery, as Mrbrock points out.

Anyway, looking at some recent charges, with incomplete charges' data removed, I see:

Mi driven	Hours charged	Mi added	Charge efficiency	Kwh added	Kwh input	Avg kwh/mi	Start %	End %
22.7​	2.32​	32.9​	91​	7.5​	8.2​	0.36​	65%​	75%​
21​	1.85​	27.2​	98​	6.5​	6.6​	0.31​	66%​	75%​
25.9​	2.68​	38.1​	93​	9​	9.6​	0.37​	63%​	75%​
25.7​	1.58​	21.9​	92​	5.2​	5.6​	0.22​	68%​	75%​
27.9​	2.07​	29.8​	96​	7.2​	7.5​	0.27​	65%​	75%​
20.4​	1.82​	26.3​	96​	6.3​	6.5​	0.32​	66%​	75%​
28.1​	2.3​	33.3​	97​	8​	8.2​	0.29​	64%​	75%​
171.7​		209.5​	94.71​	49.7​	52.2​	0.31​
ttl mi	ttl charge time	ttl mi added	avg efficiency	ttl added	ttl input	avg kwh/mi

I also notice while I charge to 75%, it's down to maybe 73% charge when I get in to drive, meaning these charging sessions after a drive add in the ~2% standby losses.

In addition, the following mini charging sessions were recorded by TezLab. Not all seem to be recorded (I see the charger "on" but get no report). You can see how crappy the efficiency is on these mini charges, when no one drives anywhere.

I am mainly adding this info to show how variable regular charge efficiency is (above) and what the no-trip charge efficiency is (below).

Efficiency//kwh added//kwh input
52% . . . . . . .0.9 . . . . . . .1.7
47% . . . . . . .1.1 . . . . . . 2.3
53% . . . . . . 0.8 . . . . . . 1.5
29% . . . . . . 0.5 . . . . . . 1.7
33% . . . . . . 0.5 . . . . . . 1.5
50% . . . . . . 1.3 . . . . . . 2.6
avg:44% . . . ttl:5.1 . . . ttl:11.3