# Forums

## Can someone check my math? Are Tesla cars really 36 times as energy efficient as ICE?

Running some quick numbers, MS60 has a 60kWh battery, and can go 210 miles (EPA). That's 3.5 miles per kWh.

60 kWh has the same energy as 216 MJ (same number in different units). Gasoline has an energy density of 129.4611 MJ/Gal (I'm American, deal with it). That means that 60 kWh has as much energy as ~1.668 gallons of gasoline. To get a 210 mile range out of 1.668 gallons of gasoline, you'd be running at 125.86 miles per gallon.

125.86/3.5 = 35.96

I knew that EVs were more energy efficient than ICE cars, but 36 times as efficient?

P.S. Significant figures, I know. I just finished a week-long vacation, cut me some slack.

carlk | 7 August 2016

125 miles per gallon equivalent for MS60. 25 mpg for Mercedes S class. That's 5 times efficiency.

Bighorn | 7 August 2016

You compared a gallon of gas to a kWh of electricity.

dansplans | 7 August 2016

For most consumers, the only comparison that counts, is the savings between fuel and electricity, on an ongoing basis. Even in high price areas, it is generally no more than 25-30% of the cost of fuel. Most areas, particularly with cheap night time rates, can do much better than that.

rdcollaborative | 7 August 2016

@Bighorn
You said "You compared a gallon of gas to a kWh of electricity."
No he didn't.

rdcollaborative | 7 August 2016

@bmalloy0
You asked "Can someone check my math?"
OK

You have the MJ content of 60kWh correct.
You have the US gallon calculation correct.
The calculation "125.86/3.5 = 35.96" is what threw you.

You really want the mpg calculation for an EV which is 210/1.668 = 125mpg
Then compare that to an ICE vehicle which averages 25mpg
So an EV is 5X as efficient as an ICE.
When it comes to cost, an ICE averages (and there is a wide variation due to electricity pricing) 7X the cost of an EV.

Bighorn | 8 August 2016

MPGe/M/kWh is what he did, so what I said.

bmalloy0 | 8 August 2016

@carlk, @bob.naughtan

Thanks, brain is still in reboot mode. 5x sounds FAR more plausible!

Red Sage ca us | 8 August 2016

MPGe, as presented by the EPA, seems to be a financial calculation, rather than a direct calculation of energy expended. Though, yes, when you check Wikipedia, an energy calculation is presented there. Ultimately, I get the impression that MPGe is meant to show ICE vehicles in the best possible light, and even that isn't too flattering. Even so, I find it personally offensive that plug-in hybrid gasoline cars seem to repeatedly be granted an MPGe rating that is twice that of their regular hybrid gasoline versions.

___42 MPG__-_Ford Fusion Hybrid
___88 MPGe_-_Ford Fusion Energi Plug-in Hybrid

jordanrichard | 8 August 2016

As dansplans pointed out, people don't pay attention ie; care about the energy in a gallon of gas or which is more efficient. It is how much they spend on gas vs electric.

For my self, my MS cost 300% less to "fuel" than what I would have spent on gas otherwise. Our other car is MB SL500, requires premium gas and averages 20 MPG. At present gas prices, that works out to \$.15 per mile vs an average of \$.05 per mile for the MS.

Bighorn | 8 August 2016

@jordan
I saw another place where you mentioned the cost being 300% less. 100% less of something is zero, so what I think you meant is 66% less. Put the other way, gas is 200% more.

andy.connor.e | 8 August 2016

Take into consideration that the MPG you get from gasoline, nowhere near even 40% of the energy in the gasoline is going towards torque.

dansplans | 9 August 2016

@andy.connor.e

Solar panels are only about 20% efficient at capturing energy from sunlight. (or less). Relative energy losses or potential aren't really the point. If that was all that mattered, then no one would be interested in solar to storage to EV as ultimately the efficiency would be quite limited at around 10-15% of potential energy available.

rdcollaborative | 10 August 2016

@dansplans
You said "Solar panels are only about 20%"
There are now panels which are 22.5% efficient.

You said "as ultimately the efficiency would be quite limited at around 10-15% of potential energy available."
Where id this number come from?
It is quite incorrect.

dansplans | 10 August 2016

Must you play the fool?

About 20% is accurate in the real world. Useable energy is much less, as solar rarely operates at maximum efficiency. Consider location in the world for maximum and minimum potential. Now consider dust and other interference that limits potential. Now add in losses when sending to storage medium. Now add in losses when sending to PV.

10-15% was being overly generous as to usable electricity efficiency.

I'm surprised you didn't use multilayer panels as your upper limit efficiency measure.

rdcollaborative | 10 August 2016

@dansplans
You said "Must you play the fool? About 20% is accurate in the real world."
The number I quoted, which you should have noticed was to the decimal point, is from real world panels you can buy right now. You should have bothered to check.

You said "10-15% was being overly generous as to usable electricity efficiency."
No it is not. Not only did you not provide a calculation, but you are very wrong.

You said "I'm surprised you didn't use multilayer panels as your upper limit efficiency measure."
I had not need to do so. The 22.5% are from single layer silicon panels.

dansplans | 10 August 2016

I'm surprised you didn't quote the current world record...lol...around 24% for those who might wonder.

The only thing which I repeatedly err in, is bothering to reply to any thread you hijack. Perhaps I am slightly "insane" lol. Or not, as I am not going to repeat this error.

So I will resort to your favorite method, and simply copy and paste someone else's words.

"@bb0tin
it would appear that no one on this forum will ever live up to your imaginary 'perfect world'.
We say black, you say purple; we say cold, you say lukewarm; we say stop, you say slow down.
Your unreal expectations exceed any norm known to mankind.
For anyone to attempt to satisfy you is beyond the realm of possibility.
You really need to get some help via counseling on how to play well with others.
All the best and hope you recover soon."

bob.naughtyn | 10 August 2016

@dansplans
I was the only poster who actually bothered to check, and usefully comment on, the math of the OP, as they requested. The OP even thanked me for it.

I do not understand the rest of your post. You quoted 10-15%, and I am simply asking you show how you got that number., I know it is totally bogus, but did not initially say so. Instead I asked how you got it. You refused to provide that information, so not you get the simple; it is nothing but ignorant, incorrect opinion, and you know it. But you felt the need to post your bogus numbers on the forum as fact anyway.

DTsea | 11 August 2016

Bob.n,

When i got a bid for housetop solar i was quoted 10W per square foot, which works out to about 105-110 W/sq m. Solar flux at sea level is about 1kW per sq m.... so about 10%

bob.naughtyn | 11 August 2016

@DTsea
Solar panels are over 20% efficient now, and can be purchased at 22.5%.
This is the fact of the matter, and can be verified using a google search.

Silver2K | 11 August 2016

bighorn you're right +1

Silver2K | 11 August 2016

my tourettes disorder just kicked in

Ross1 | 11 August 2016

Just for the moment I am going to change my name to bob.naughty, so I can answer Silver.

@SilverP85plus: You just said "my tourettes disorder just kicked in".
That is an insult to people with Tourette's Syndrome, like you have previously insulted people with Asperger's and Schitzophrenia.......

Now back to @Ross.

Ross1 | 11 August 2016

Schizophrenia.

Silver2K | 11 August 2016

but but but.....

SCCRENDO | 11 August 2016

@Ross +1. You tell him

DTsea | 12 August 2016

Bob.n,

True. In fact for space applications there are 40% efficient panels

But, they cost \$10000 (US) per square foot.

Most panels for home use are 11-15% effcient according to pureenergies.com. higher efficiency will coat more per installed watt.

DTsea | 12 August 2016

Oops. Cost not coat

mknower | 12 August 2016

@DTsea
Most panels were about 15% efficiency a few years ago, but it is no longer the case. There are multiple suppliers of panels over 20%, including SolarCity. Millions upon millions of these panels have been shipped.

Ross1 | 12 August 2016

@bob is now @sarah

mknower | 12 August 2016

@Ross
You have previously posted my real Firstname and Lastname.
You posted that you do not hide behind anonymity on the web and use your real name, but all you post is Ross which ensures your anonymity.
What is your real Firstname and Lastname?

Silver2K | 12 August 2016

@man making believe he's woman (weird)

he posted your real name (if it's real) because he found it, not because you volunteered it. If you want his real name you have to find it, not volunteered to you.

mknower | 12 August 2016

@SilverP85plus
I am not making believe I am a woman. You obviously missed the reference.
My real name has been posted multiple times on this forum, by multiple people. I deliberately make it easy to find. Note the word 'deliberately'. Every one of those people who post my real name refuse to post theirs. They deliberately remain anonymous. They are trolling cowards. However, Ross takes the cake. He claims he does not remain anonymous, posts my real name, but refuses to post his own.

RedShift | 12 August 2016

Dude looks like a lady...it was playing the other day in my Tesla. As hummed along to the lyrics, I just realized how risqué they really are! Never thought about them until that time.

And before some clever dickensian points out this has nothing to with the all important and hallowed OP, I am outta here. :-)

Silver2K | 12 August 2016

Miles Dyson

RedShift | 12 August 2016

@silver

Oh yeah? Why did you invent the AI CPU, mofo?

Ross1 | 12 August 2016

SCCRENDO's been fiddling with @bb lol
Hope you like the result!

Ross1 | 12 August 2016

@bb0tin: aka Sarah
1: You promised not to respond to me. Therefore in your own words you are a lying hypocrite.
2: Multiple repetitive posts are offensive. I heard you the first time, and the next 100.
3: I already said, association here with you wouldn't help my relative's business, which has eventuated since we first corresponded here.
4: Any association with you is doomed to failure.
5: So go buy a Tesla and enjoy yourself. There are plenty available in RHD for import to NZ.
6: I am only responding now to get you off my back, and I respectfully suggest, off the fora.
7: Read my thread about entering the Tesla market at low cost, it might help you get some electric wheels. (How much fun can a nice girl (like Sarah) have?)
8: Do not, do not reply.

mknower | 12 August 2016

@Ross
Regarding 1) We have been through this several times before. I said I would respond to your personal insults. Your post did not seem like that to me, or are you saying that you did intend it to be a personal insult?
Regarding 2) Yes, you keep on making posts about me, and used to make personal insults as well, and they are indeed offensive to me
Regarding 3) Codswallop. You made your hypocritical statement that you do remain anonymous just last week. Your poor excuse does not wash.
Regarding 4) You are not associating yourself with me by giving your name.
Regarding 5) WTF?
Regarding 6) You will not get me off you back until you provide your real name, or stop posting about me. You stated that you do not remain anonymous on the web, and posted my real name. Until you provide your real full name you are a hypocritical bully and coward.
Regarding 7) You need to pay attention. I have already posted several times that I do.
Regarding 8) You are not my master

mknower | 13 August 2016

@SilverP85plus
I do not recall Miles Dyson being a coward

Silver2K | 13 August 2016

RedShift

HEY! only Bighorn says MOFO here!

Besides, I invented the A.I to control electronically linked weapons and defend the United States. da sheet went nuts!

RedShift | 13 August 2016

@silver

You think you are so clever. Try creating a life.

Silver2K | 13 August 2016