60KWH usable capacity on 2018 model S 75D?

[EMC2]

Hi, Guys , I have a 2018 Model S 75D. It’s about 1 month old and has done 2000KM. I am in Australia and the temp is perfect now about 10-20c. My AVG. energy consumption is about 200wh/km.

I usually charge the car to 80% during night. When I found the battery drop to 60% , the console showed 11.8KWH been used “since last charge”. Which means 20% of battery equal 11.8KWH, it converts to 100% is 59KHW. I have been keep watching these figures for a few days now, when battery drop from 80% to 70%, My usage is about 5.0KHW (10% = 5KW) , when it goes to 50%, the usage is about 17.3 KWH( 30%=17.3KWH), when it down to 40%, the usage is about 23.6KWH (40%= 23.6KWH), all those figures are telling the total battery pack is about 58,59KWH.

Did I miss something here? Or maybe someone can give some explanation?

 

[croman]

Hi, Guys , I have a 2018 Model S 75D. It’s about 1 month old and has done 2000KM. I am in Australia and the temp is perfect now about 10-20c. My AVG. energy consumption is about 200wh/km.

I usually charge the car to 80% during night. When I found the battery drop to 60% , the console showed 11.8KWH been used “since last charge”. Which means 20% of battery equal 11.8KWH, it converts to 100% is 59KHW. I have been keep watching these figures for a few days now, when battery drop from 80% to 70%, My usage is about 5.0KHW (10% = 5KW) , when it goes to 50%, the usage is about 17.3 KWH( 30%=17.3KWH), when it down to 40%, the usage is about 23.6KWH (40%= 23.6KWH), all those figures are telling the total battery pack is about 58,59KWH.

Did I miss something here? Or maybe someone can give some explanation?

Those figures include all power used not only for propulsion.

Only the BMS can tell you a more accurate capacity estimate. Per wk057, I think the current 75kwh pack is a total capacity of 72.4kwh and available capacity of 68.4kwh.

 

[EMC2]

Thanks!
Yes, Around 72,Kwh of total capacity is what I expected.
I was driving when the battery drop from 80%to 70%, So, I basically can assume that the first 5KWH usage was pretty accurate figure . and also was driving from 50% to 40% ( 6kwh this 10%) . Unless, all the traffic lights stops power consumption, aircon power usage during the driving are not included .

 

[whitex]

Those figures include all power used not only for propulsion.

Only the BMS can tell you a more accurate capacity estimate. Per wk057, I think the current 75kwh pack is a total capacity of 72.4kwh and available capacity of 68.4kwh.

Do you have a source of this data? Last I looked, the 72KWh was the usable value, the total with anti brick buffer was 75KWh. 90 was the last battery Tesla was lying about (e.g. battery sold by Tesla as 85KWh was actually 81KWh with 77KWh usable).

 

[croman]

Do you have a source of this data? Last I looked, the 72KWh was the usable value, the total with anti brick buffer was 75KWh. 90 was the last battery Tesla was lying about (e.g. battery sold by Tesla as 85KWh was actually 81KWh with 77KWh usable).

You seem to be right. 75kwh total, 72.6kwh useable. Seems odd the buffer for the 75 pack is only 2.4kwh vs. ~4kwh for other packs.

Tesla, please stop making up specifications... | wk057's SkieNET...

 

[EMC2]

Do you have a source of this data? Last I looked, the 72KWh was the usable value, the total with anti brick buffer was 75KWh. 90 was the last battery Tesla was lying about (e.g. battery sold by Tesla as 85KWh was actually 81KWh with 77KWh usable).

Do you see any problem of the way I did my calculation. What figure (power consumption "since last charge") will you get if your battery drop 20%, say from 80% to 60% ?

 

[whitex]

Do you see any problem of the way I did my calculation. What figure (power consumption "since last charge") will you get if your battery drop 20%, say from 80% to 60% ?

The problem with doing such calculation is that you don't have all the variables. Here as some thing you might not know:

1. What Tesla gives in terms of remaining capacity is an estimate. The algorithm for this estimate has varied in the past between software versions. You might be surprised to find out that while parked and not plugged into any power source, the % state of charge can actually go up. Doesn't happen very often, and usually doesn't go up by more than a mile or rated range, but it does happen. and of course we know the car is not charging from just parking there.
2. The usage that the car shows applies to driving. Last I did this exercise it didn't include things like HVAC, or battery internal loses (batteries have an intrinsic source resistance which uses energy and heats the batteries up, while the cooling system then has to take that heat away), and possibly a few other things, like anything running off the 12V rail which runs from a 12V battery, but that battery is recharged from the large battery since there is not alternator in EV's.
3. The car uses power to keep the battery within desired temperature range, that means cooling or heating, depending on the weather. That can eat up your battery while parked, and the first few miles of driving to bring it to a more narrow temperature range optimal for driving.

Bottom line, you'll drive yourself crazy trying to get all the calculations to line up. I know, I've been there. I once even hooked up a camera to take pictures of the dash every 10 seconds as the car was driving, then what I expected the rated range should be based on reported Wh/mile, and actual rated range showing (see below). Even if you end up with Wh/mile (or km) exactly equal the rated value, you will find you're not going to actually get the rated miles. IIRC correctly, for my S60 I had to add about 500W-1000W constant unaccounted for (in Wh/mile) draw to the equations to make things add up, in addition to parking loses.

Just for laughs, below is one of my least efficient drives between 2 superchargers in a P85D. The rated 259 miles turns into ~150 miles when driving 80-90mph, and this wasn't freezing temperatures either. I actually had to slow down a little towards the end so that I could reach the next supercharger. Sorry, I don't remember what Wh/mile the car showed, but I'm sure it was high.

Summary , don't drive yourself crazy - there is nothing wrong unless there is some really large discrepancy.

 

[E-Ryc]

On my Mar 2017 S75D (41.000km), the diagnostic (scan my tesla) says:
Nominal full pack: 70.2kWh
Usable full pack: 66.2kWh

 

[GSP]

Do you see any problem of the way I did my calculation. What figure (power consumption "since last charge") will you get if your battery drop 20%, say from 80% to 60% ?

You only can get a very rough idea of the available battery capacity by extrapolating 20% use to 100%. The only way to measure useable capacity accurately is to charge to 100% and discharge to near zero. This limits extrapolation to only a few percent.

As others have noted, Tesla reserves some capacity for "anti-bricking" protection, so the useable capacity will be less than 75 kWh, even when new.

GSP

 

[EMC2]

Hi, Whitex Thank you a lot for providing much detailed answer. You had done a lot of home works!
however the 500W-1000W constant unaccounted for (in Wh/mile) sounds not right, are you mean 50-100w ?

 

[EMC2]

On my Mar 2017 S75D (41.000km), the diagnostic (scan my tesla) says:
Nominal full pack: 70.2kWh
Usable full pack: 66.2kWh

Your figures looks OK for me.
It's a good idea to get it checked by Tesla service centre.

 

[E-Ryc]

@EMC2 I put the values here just to show the expected values are nowhere close to 75kWh.

 

[SuisseDriver]

Did I miss something here? Or maybe someone can give some explanation?

Same here. I have a S, 5D from November 2017.
I do quite a long trip where i charge to 100% and can go down until 5-7%.
The extrapolation is giving me a usable ranfe around 65-66kWh.
I never understood that and cannot explain.

Some people are saying that the reported consumption is only the consumption of the motors and not the total consumption, which i find a weird explanation as it means that it should not change much between summer and winter but I definitely see a big increase in winter when using heating or heating the pack so i am pretty sure that the consumption reported DOES include the equipment consumption and is the total consumption.

So i have no clue whqt to do from the 72.6kWh usable that i have never seen..

 

[iCharge]

The problem with doing such calculation is that you don't have all the variables. Here as some thing you might not know:

1. What Tesla gives in terms of remaining capacity is an estimate. The algorithm for this estimate has varied in the past between software versions. You might be surprised to find out that while parked and not plugged into any power source, the % state of charge can actually go up. Doesn't happen very often, and usually doesn't go up by more than a mile or rated range, but it does happen. and of course we know the car is not charging from just parking there.
2. The usage that the car shows applies to driving. Last I did this exercise it didn't include things like HVAC, or battery internal loses (batteries have an intrinsic source resistance which uses energy and heats the batteries up, while the cooling system then has to take that heat away), and possibly a few other things, like anything running off the 12V rail which runs from a 12V battery, but that battery is recharged from the large battery since there is not alternator in EV's.
3. The car uses power to keep the battery within desired temperature range, that means cooling or heating, depending on the weather. That can eat up your battery while parked, and the first few miles of driving to bring it to a more narrow temperature range optimal for driving.

Bottom line, you'll drive yourself crazy trying to get all the calculations to line up. I know, I've been there. I once even hooked up a camera to take pictures of the dash every 10 seconds as the car was driving, then what I expected the rated range should be based on reported Wh/mile, and actual rated range showing (see below). Even if you end up with Wh/mile (or km) exactly equal the rated value, you will find you're not going to actually get the rated miles. IIRC correctly, for my S60 I had to add about 500W-1000W constant unaccounted for (in Wh/mile) draw to the equations to make things add up, in addition to parking loses.

View attachment 348014

Just for laughs, below is one of my least efficient drives between 2 superchargers in a P85D. The rated 259 miles turns into ~150 miles when driving 80-90mph, and this wasn't freezing temperatures either. I actually had to slow down a little towards the end so that I could reach the next supercharger. Sorry, I don't remember what Wh/mile the car showed, but I'm sure it was high.

View attachment 348015


Summary , don't drive yourself crazy - there is nothing wrong unless there is some really large discrepancy.

golden words, right here. Bottom line, you'll drive yourself crazy trying to get all the calculations to line up.
Being the techie nerdy kind, I decided that I wont run any complicated maths / calculations when I got a MS. I use in dash navigation and cruise control [ plus EAP if available ] set and let it do its thing. Check what % will the battery be at my destination and if that is acceptable to me given charging options available at destination.
I always keep a 30 mile buffer when in city and 50 when in boondocks

 

[Jan Fiala]

The usage shows all the power drawn from the pack. The difference is the heat loss in the battery. Higher draw = higher heat loss. i.E. go slowly and you'll get the total consumption very close to the max. usable capacity. Go really fast and you'll see total consumption between 40-50kWh and the pack will be already empty.

 

[EMC2]

I had a separate meter installed by the electricity company which just for the wall charge. I've been monitoring the meter for last a few days. the figures on the meter were totally make sense. ( like the car sucked in 30.5KWH for 40%, which equal to 76.5kwh for 100%) .
So, Whitex was very right, in my case, I had to add about 40Wh/KM constant unaccounted usage for draw to the equations to make figures add up. My average usage is about 210WH/KM ( 336wh/Mil) and add 40wh/km make 250wh/km. and get about 300KM (187Mil) real world range.

 

[keithf]

On my Mar 2017 S75D (41.000km), the diagnostic (scan my tesla) says:
Nominal full pack: 70.2kWh
Usable full pack: 66.2kWh

My JULY BUILD 2017S75D is similar with 70.8 nominal full and 66.8 usable full

 

[Jan Fiala]

I had a separate meter installed by the electricity company which just for the wall charge. I've been monitoring the meter for last a few days. the figures on the meter were totally make sense. ( like the car sucked in 30.5KWH for 40%, which equal to 76.5kwh for 100%) .
So, Whitex was very right, in my case, I had to add about 40Wh/KM constant unaccounted usage for draw to the equations to make figures add up. My average usage is about 210WH/KM ( 336wh/Mil) and add 40wh/km make 250wh/km. and get about 300KM (187Mil) real world range.

The meter is counting AC, battery is charged by DC, there is around 10pct conversion loss. So deduct 10pct from the meter numbers before calculating ...

 

[Chaserr]

Check volts when charged to 100%. If you charge to significantly under 4.2v (like 1.10v, not 1.98+V) you may be a victim of batterygate capping. Sudden Loss Of Range With 2019.16.x Software

There are lots of other reasons to see less capacity or observe fewer miles. Capping is a growing problem but the % is still fairly small compared to how many cars are out there so it's unlikely you are downgraded but checking volts is the only way to be certain.