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Model 3 LR Battery Size. What am I missing?

I tried to find some information on this before I posted, but feel free to send me a link to this answer.

The EPA currently says the Model 3 LR has 353 miles of total range. It also says the car use 25 kwh/100 miles or 250 wh/mile.


Simply multiplying this out 353*250 suggests a battery size of 88,250 watt hours or 88.3 kWh

I haven't seen anyone suggest the battery capacity is this high. Also real-word results are considerably lower than this in general. What am I missing? BTW, I'm not complaining about lack of range, etc and I've owned and loved my P3d- for 2.5 years. Just wondering about the discrepancy.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
14,322
18,156
Riverside Co. CA
I tried to find some information on this before I posted, but feel free to send me a link to this answer.

The EPA currently says the Model 3 LR has 353 miles of total range. It also says the car use 25 kwh/100 miles or 250 wh/mile.


Simply multiplying this out 353*250 suggests a battery size of 88,250 watt hours or 88.3 kWh

I haven't seen anyone suggest the battery capacity is this high. Also real-word results are considerably lower than this in general. What am I missing? BTW, I'm not complaining about lack of range, etc and I've owned and loved my P3d- for 2.5 years. Just wondering about the discrepancy.

Everything that is known about the 2021 and battery is in this large master thread:


There is a lot of discussion on there on type of battery, constants, etc.

Please direct any further discussion on this topic to that thread.
 
Here's what you are missing : EPA consumption ratings include power loss when charging, so as to indicate the total "cost per mile" of driving the car. Typical charging loss is in the range of 88% of the input power going into the battery but I don't have the exact number.

You cannot multiply that consumption number by a total number of miles to figure out the battery capacity. You would need the number without the charging loss. On my 2020 LR AWD Tesla seems to use 143wh/km, as a reference.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
11,709
15,193
San Diego
Simply multiplying this out 353*250 suggests a battery size of 88,250 watt hours or 88.3 kWh

I haven't seen anyone suggest the battery capacity is this high. Also real-word results are considerably lower than this in general. What am I missing? BTW, I'm not complaining about lack of range, etc and I've owned and loved my P3d- for 2.5 years. Just wondering about the discrepancy.

As @GtiMart says, it's charging losses you are missing. There's a lot of rounding errors on your number, but the EPA Data says:
88.54kWh to charge the battery, 78.56kWh to discharge it.

Your calculation won't work out exactly correctly, due to these rounding errors (it's only 2 significant digits in your calculation). But the rating is derived from that same basic information, and your calculation is basically correct in concept.

AC MPGe 134MPGe is the rating, so:

AC Wh/mi = 33705Wh/Ge / 134mi/Ge = 251.5Wh/mi (This is not correct, due to rounding error on the 134MPGe. It's actually 251.2Wh/mi, see below..)

City Range: 494.54mi*0.7472 = 369.5mi
Highway Range: 446.78*0.7472 = 333.8mi
(Range: 369.5mi*0.55+333.8mi*0.45 = 353.4mi)

MPGe City: 33705Wh/Ge * 369.5mi/88541Wh = 141MPGe
MPGe Highway: 33705Wh/Ge * 333.8mi/88541Wh = 127MPGe

MPGe = 1/( 1/141MPGe * 0.55 + 1/127MPGe * 0.45) = 134MPGe (134.2MPGe)

If you want the DC Wh/mi & MPGe just use the 78.56kWh number in the above formulas. So DC Wh/mi is about 222.9Wh/mi (78.56/88.54*251.2Wh/mi). That's a little off from the rated constant because Tesla uses 77.8kWh for a full battery and not 78.56kWh (what they actually pulled from it during the test). (77.8/88.54*251.5Wh/mi = 220.7Wh/mi).

This is off from 220Wh/mi mostly due to Tesla derating the range from 353.5 to 353 miles, which takes it to 220.4Wh/mi. QED ;). That's the constant used to find out exactly what your current battery capacity estimate is, as explained elsewhere.

My 0.7472 factor (the big kahuna!) may not be exactly correct but it's close. So a little bit of false precision here. It's probably accurate to three significant digits, but whatever. Details; you get the idea.
 
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... Which means you guys rely on people that actually read the whole thing, and we have to continuously re-write the same answers. Yay... 🙃😀
So you think every forum member should read dozens and dozens of pages of every master thread so everyone knows everything that is in those sections?

How about this as a follow up question- is there a way to search on just a single topic? That would help, but I didn't seem to find a way to be able to do that. There is a new option in the search called 'threadloom' but there isn't any information on that in the search box. Some help somewhere might be nice
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
11,709
15,193
San Diego
At least some user has posted this detail. This little depends when Tesla has enough Panasonic batteries that they can move assembly line to use Panasonic.
There is no evidence of this actually happening yet (what you are referring to are COC code tables in Europe I think) . All LR non-P have Panasonic in the US. They all have 77.8kWh packs, the Performance has 82.1kWh.

When this changes, it will likely be obvious. At some point, it does seem likely that AWD will get larger 2170L packs; the question is when. But for now it is 2170 Panasonic, 77.8kWh.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
14,322
18,156
Riverside Co. CA
So you think every forum member should read dozens and dozens of pages of every master thread so everyone knows everything that is in those sections?

How about this as a follow up question- is there a way to search on just a single topic? That would help, but I didn't seem to find a way to be able to do that. There is a new option in the search called 'threadloom' but there isn't any information on that in the search box. Some help somewhere might be nice

I cant answer your threadloom question because I dont know. FWIW those master threads dont exist with the intention that someone is going to read all the pages of them. They exist, for the most part, to consolidate discussions that would otherwise overrun the forum. "what size is my battery" (or anything about the battery, like "why am I not getting my rated range" for example) are such popular topics that they would overrun the forum otherwise.
 

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