P85D - 310 wh/mi not good enough to make rated any more?

[Peter Lucas]

Agreed. I never chime in on those threads where people worry about not getting actual real-world rated miles. Too many variables. Just using the baseline reported 100% gives you at least an indication of relative battery health compared to others. In your case, your battery is “healthier” than mine by a decent amount.

The point is that the cars display of range is not any indication of battery health.

 

[ran349]

BTW, I was wrong saying my "nominal full pack" rating was 72-73kwh. That reads 77.8kwh. My usable full pack is 73.8kwh. From there I could calculate my degradation as about 5.5%. This is pretty darn close to the "error" read on projected vs. actual consumption.

I am thinking a normal 85kwh pack would be 77.8kwh as mine says, but I could be wrong. I am curious what other people have for a usable full pack. My lifetime (just over 4k miles) consumption is 347wh/mi, though that is mostly cool/cold weather. Wheel/tire choice also has a noticeable impact. I have 19" cyclones and MXM4s which are pretty good from an efficiency standpoint.

I believe that is correct. In your case, a new 85 pack would be 253 x .310 = 78.43 kWh. So your case of 77.8 is consistent with your 251 rated miles, meaning very little degradation.

 

[David99]

Tesla is cheating. They include the buffer into the rated range when at 100% and as you discharge the battery it is gradually taken out. With the buffer the rated range consumption would add up.

I posted about it here
This is why you can't get 'rated range'

 

[beatle]

Ah ha, that's a good thread. I honestly did not read most of the megathreads when I started here, but that looks like a good one to dig into. I find it interesting that your 295wh/mi is actually higher than my 292, though we are comparing 85 and P85D cars.

 

[ran349]

Ah ha, that's a good thread. I honestly did not read most of the megathreads when I started here, but that looks like a good one to dig into. I find it interesting that your 295wh/mi is actually higher than my 292, though we are comparing 85 and P85D cars.

Per Jason Hughes, the equivalent comparison would be 295 for the RWD 85 vs. your 310 for P85D:

• All RWD Cars (non-Performance and Performance): 295 Wh/Rated Mile
• All Pre-refresh Model S Dual Motor, non-Performance: 290 Wh/Rated Mile
• Refresh Model S Dual Motor, non-Performance under 100 kWh: 285 Wh/Rated Mile
• Model X Dual Motor, non-Performance under 100 kWh: 320 Wh/Rated Mile
• Model S Dual Motor, Performance under 100 kWh: 310 Wh/Rated Mile
• Model X Dual Motor, Performance under 100 kWh: 333 Wh/Rated Mile
• Model X Dual Motor, Performance 100 kWh: 342 Wh/Rated Mile

 

[sorka]

Tesla is cheating. They include the buffer into the rated range when at 100% and as you discharge the battery it is gradually taken out. With the buffer the rated range consumption would add up.

I posted about it here
This is why you can't get 'rated range'

You can see this on the CANBUS as the displayed SOC diverges from the scanned SOC. That said the car won't die until the scanned SOC hits 0% provided that the BMS doesn't shut down the car because a module went below the minimum safe voltage. A battery in good condition and balance can and will use that buffer for travel.

Unfortunately, a slightly imperfect battery with a little too much throttle near the end and a the BMS will shut you down even before you hit a displayed 0%...in the worse cases.

But there is another source of wh / mile used / remaining capacity left discrepancy that is not mention anywhere near enough. The wh / mile used since say last charge includes regenerative breaking which is not 100% efficient. The more regen you do, the less efficient the charge use will have been.

My lifetime average is 303 wh/mile in my P85DL. If I drive a long distance without any regen, say I'm on a perfectly flat highway for a few hours where and I don't use any regen to slow down but instead coast down if I need to reduce speed say for traffic, my use ends up being 99.something % efficient when calculating my wh / mile usage against the remaining scanned capacity of the battery(We already know the displayed SOC diverges up to the buffer amount).

That said, my lifetime average is 303 wh / mile because it includes city driving and ludicrous launches. My highway travel is far better than that. At 70 mph, I typically get 260 to 295 wh / mile on my 260 round trip commute which includes a major mountain pass. It's closer to 260 in the summer and closer to 300 in the winter.

 

[David99]

@sorka you are making some good points. Having driven many road trips where I have driven continuously from charging to 'empty' I have also noticed that the amount of energy one can take out of the battery varies. Fast driving with high energy consumption, lots of hard acceleration makes less energy available. 'Gentle' driving will allow more energy to be available. I was able to see that in two ways. #1 when the battery drops down to say 10% at the end of a 2 hour drive, the battery voltage seems to be a little higher when the car was driven carefully compared to when I was driving very fast or with lots of sprints.
The other, more obvious way to see the difference is measuring the amount of energy taken out during a longer drive. If I start with 50 kWh remaining in the battery, the amount of energy I am able to get out is usually between 49.6 and 49.1 depending on how I drive. Driving with high power causes higher losses inside the battery.

 

[sorka]

There is one more very tiny source of difference. The wh/m odometer counts hvac but doesn't count lights, stereo, etc. So there's still a small discrepancy there but it's usually a fraction of 1%.

Also, if you you sit overnight on the same charge, the wh/m odometer doesn't include vampire drain which can be considerable.

 

[aerodyne]

@sorka you are making some good points. Having driven many road trips where I have driven continuously from charging to 'empty' I have also noticed that the amount of energy one can take out of the battery varies. Fast driving with high energy consumption, lots of hard acceleration makes less energy available. 'Gentle' driving will allow more energy to be available. I was able to see that in two ways. #1 when the battery drops down to say 10% at the end of a 2 hour drive, the battery voltage seems to be a little higher when the car was driven carefully compared to when I was driving very fast or with lots of sprints.
The other, more obvious way to see the difference is measuring the amount of energy taken out during a longer drive. If I start with 50 kWh remaining in the battery, the amount of energy I am able to get out is usually between 49.6 and 49.1 depending on how I drive. Driving with high power causes higher losses inside the battery.

I thought that more aggressive driving would primarily increase consumption because of increased Regen. However it occurred to me that whenever high power is demanded from the pack, energy is lost due to pack resistance, and resistance in the motors and perhaps slightly in the conductors, which is lost as heat.

So it makes sense to apply min power and min Regen use to increase range.

 

[joltheadq]

That's not very helpful. Most of what I've read has been a specific cut to the rated range. Mine remains pretty high. Has anyone else seen a reduction in the wh/mi needed to make rated range?

Helpful to ask the v8 guys that aren’t limited.

 

[aerodyne]

Helpful to ask the v8 guys that aren’t limited.

I am no longer on V8, but looking at my records when I was on V8, circa fall 2018, my rated range was near new, 269/270.

However, even then, the rated range was based on nominal full pack, not usable full pack.

As others have noted, the consumption needed to make the rated range drops as you drive down to the buffer. So, if you really want to drive say from 90% to 10%, reduce the RR by about 6%, to about 275 Wh/mi. I am averaging 298 since I bought the car, so I just reduce my expectation of maximum range by 10% or 240.

Also as others have noted, this "Trick" of using the buffer also hides degradation.

Car says I have 259/270 RR, but I really have 77.5/71.3 KwH usable.

Sorry if this info has been posted before, still trying to get my head around this behavior...