September 2022 European Model 3 RWD Delivered cars have a 7.5kwh buffer instead of 2.5kwh, Reducing the 100% - 0% range by 10% over previous 22 cars

[reni10]

I recently purchased a new 2022 Model 3 RWD with the understanding that it had about a 60.5kwh nominal battery with approx 58kwh usable with a 2.5kwh buffer as this was what was delivered on all RWD models since the start of 2022.

I noticed shortly after pickup of my car that I could never get more than 52kwh used from 100% to 0% according to the trip meter in the car.

This seemed very strange to me as I would have thought that without using the HVAC I would be seeing closer to 57kwh used but after multiple charges to 100% and discharge back down to 0% I am still only seeing a maximum of 52kwh used!

I then came across the video from Telsabjorn showing the actual buffer in a recently delivered car and it is as I am seeing in my car:

A massive 7.5kwh buffer and no way to make this smaller therefore once I get to 0% I actually have another 10% but no way of knowing how accurate this is!

This is very poor from Tesla and they refuse to see it as a problem even though their advertisement for my car gave a WLTP range of 491km but this is only achievable using their figures if there is a 60kwh pack with 2.5kwh buffer and is not achievable with only a 52.5kwn pack available as seems to be the case so I would call this false advertising and I want them to lower this buffer on my car so has anyone else noticed this and also been in contact with Tesla about it?

 

[Randy-12]

Where does Tesla list the buffer on their web site? Also where do they list the Pack size?

 

[KenC]

Maybe, it's a bug in the software.

Bjorn went another 56km and used about 6.84kWh after 0% SOC. Seems like it's there, and with more testing, you may be able to calculate a safe cushion.

 

[reni10]

Where does Tesla list the buffer on their web site? Also where do they list the Pack size?

Tesla don't list buffer or pack size but what they do list very clearly is the WLTP range and the figures they use to calculate that range which is 118Wh/100km and this equals 491km but this is only possible if you have a 58kwh usable battery and is not possible with a 52kwh usable battery so it is false to advertise that but that is exactly what they advertised for my car before, during and after I bought it but it is not possible using the figures they themselves clearly state!

 

[reni10]

Maybe, it's a bug in the software.

Bjorn went another 56km and used about 6.84kWh after 0% SOC. Seems like it's there, and with more testing, you may be able to calculate a safe cushion.

It is there alright but why would Tesla not just make it available on the actual percentage in the car so I don't have to "guess" how much is left and I know that 0% is pretty much 0% and not that 0% is actually 10% left!
It makes no sense at all to me why Tesla would do that....

 

[AlanSubie4Life]

I recently purchased a new 2022 Model 3 RWD with the understanding that it had about a 60.5kwh nominal battery with approx 58kwh usable with a 2.5kwh buffer as this was what was delivered on all RWD models since the start of 2022.

I noticed shortly after pickup of my car that I could never get more than 52kwh used from 100% to 0% according to the trip meter in the car.

This seemed very strange to me as I would have thought that without using the HVAC I would be seeing closer to 57kwh used but after multiple charges to 100% and discharge back down to 0% I am still only seeing a maximum of 52kwh used!

I then came across the video from Telsabjorn showing the actual buffer in a recently delivered car and it is as I am seeing in my car:

A massive 7.5kwh buffer and no way to make this smaller therefore once I get to 0% I actually have another 10% but no way of knowing how accurate this is!

This is very poor from Tesla and they refuse to see it as a problem even though their advertisement for my car gave a WLTP range of 491km but this is only achievable using their figures if there is a 60kwh pack with 2.5kwh buffer and is not achievable with only a 52.5kwn pack available as seems to be the case so I would call this false advertising and I want them to lower this buffer on my car so has anyone else noticed this and also been in contact with Tesla about it?

This is a (potential) feature of the RWD with LFP where the buffer can expand to up to 11% or so to avoid problems with the estimate. It is dynamic and it was to avoid problems with the LFP not being charged to 100% all the time (BMS loses track of capacity). This has been well documented here with SMT captures showing the behavior.

However, I am not convinced this is what you were seeing. How did you measure the 52kWh? This needs to be done in a single trip without stopping; you cannot spend any time in park. And you must start from 100% in the case of an LFP. And you must state your car’s rated range when charged to 100%. Then we can analyze.

Absolutely rigorous attention to detail is required to get this right.

I expect for 100% to 0% for no buffer expansion (I think default is still 4.5%) you should see 60.5kWh*0.955*0.99 = 57kWh maximum on trip meter. Again, no parking. Charge to 100% and drive continuously to 0%.

If you use “since last charge” over a period of more than 3-4 hours or so, that is completely invalid; the car does not show energy use while in Park.

 

[JOL1]

Points on rigidly following the testing (to replicate in as much as possible the WLTP laboratory type testing regime) are well made.

It does seem (in my opinion) that Tesla have chosen to adopt a prudent approach to the size of the buffer, for a variety of reasons, not least that for accurate range calculations the car's BMS requires calibration data taken from the battery, across the spectrum of stages of charge (100%, 80%,50% 10% etc) and for these to be taken when the car is "asleep" for a few hours not even using Sentry. This requires a certain pattern of charging which is user determined and not controllable by Tesla. As a result rather than the cars BMS giving inaccurate readings which could cause vehicles to come to stop, with associated dangers a more prudent...some would say "too prudent" approach is taken. Can you imagine the outcry that would result from cars dying because the range calculation was not accurate?

I had not understood that the % buffer was Dynamic "up to 11%" so my take on this is that with the right charging routine, which provides BMS with what it wants (sourcing readings at various charge % while car is left sleeping for a few hours ) the buffer may be sized more realistically.

To see this dynamic in action we would need readings from SMT over time on the same car to determine if the charging regime impacts size of buffer.

None of the above is to suggest that Tesla miscalculates the published WLTP which is a separate matter. A lot of users have the expectation that the quoted WLTP is what they should be getting in the real world . The reality is that it is complex to calculate range dynamically and also the other external variables, temperature, wind, speed, driver style, gradient ...all of which impact .

 

[AlanSubie4Life]

I had not understood that the % buffer was Dynamic "up to 11%" so my take on this is that with the right charging routine,

Specific to LFP vehicles only. And I think to some extent an emergency patch - may not stay this way.

To see this dynamic in action we would need readings from SMT over time on the same car to determine if the charging regime impacts size of buffer.

There are some SMT captures around here showing this if you search for them.

None of the above is to suggest that Tesla miscalculates the published WLTP which is a separate matter.

Yes. The tested vehicles have a BMS with the correct capacity estimate. And are charged to 100% beforehand.

The issue is apparently for a vehicle kept in the mid-range it will get several kWh off in estimate and then you can just run out of energy unexpectedly. Doesn’t change the tested range.