Battery runs like 60kw instead of 75kw

[Ninetenjack]

So I normally charge my battery to 90% and recharge at 20%, I figured that @70% (90% les 20%) I should be receiving 52.5kw (75kw times 70%) usable capacity. Except that I never show more than 42kw used.....consistently. Today I check again and at 80% so 10% used it was showing 6% consumed instead of 7.5%. At this rate if 70% is 42kw it would mean that at 100% it would be only 60kw.

Anyone else having this problem?

 

[Zoomit]

That energy usage indication only includes energy used while in Drive/Reverse. So it doesn't include any phantom losses, preheating, etc.

 

[jsmay311]

(First off, you're hurting the feelings of the "h" in "kWh". )

My first suspect here would be vampire drain, which many owners have observed can be significantly higher than the 1%/day mentioned in the manual, particularly in colder temps.

So... How many days do you generally go in between recharges? And do you have any settings turned on that increase vampire drain, like Cabin Overheat Protection or Sentry Mode?

And do you ever do you ever precondition the cabin or run the heater when the car is in Park? Any energy used while the car isn't "in gear" is excluded from the "kWh" number shown in the trip meter, so that could also contribute to what you're seeing.

 

[Ninetenjack]

That energy usage indication only includes energy used while in Drive/Reverse. So it doesn't include any phantom losses, preheating, etc.

I understand that and get the losses from pre-heating and the vampire drain but I doubt that accounts for me being over 10kw short on each cycle.

 

[Ninetenjack]

My first suspect here would be vampire drain, which many people of observed in this winter's cold temps can be way higher than the 1%/day mentioned in the manual.

How many days do you generally go between recharges? And do you have any settings turned on that increase vampire drain, like Cabin Overheat or Sentry Mode?

Also, any energy used while the car isn't "in gear" is excluded from the "kWh" number shown in the trip meter. Principally, this would include any energy used during remote start/preconditioning and climate control while in Park.

As I mentioned I get the fact that there is vampire drain etc. but a 20% lost......consistently?

 

[AlanSubie4Life]

I understand that and get the losses from pre-heating and the vampire drain but I doubt that accounts for me being over 10kw short on each cycle.

The “h” is so lonely. Left out in the cold. 10kWh is quite easy to burn through if you are exposed to these sources of loss.

You can “doubt that,” and you may be right, but the only way to determine whether you have an issue is to do a controlled experiment which eliminates/reduces the proposed sources of error. It is not difficult to do via tracking rated miles and looking at more drive-dominated charging cycles.

 

[MP3Mike]

The trip meter also isn't 100% accurate. You can't use the number it reports to determine the size of your battery.

 

[fbitz777]

I was going to post the. same issue for my 75XD (34k miles, 222 miles rated at 100%)

I NEVER have gotten more than 65Kwh even on a NONSTOP trip from 100 to 0% and that was on a warm day driving close to rated.

The most I am getting these last few months has been around 61Kwh (again single day trips) but it was colder.

If I let the car sit a day I get sometimes only 55Kwh.

AND my dedicated electric meter shows that I put about 77Kwh in each time I tried to test.

There is definitely something not accounted for in the 75XD model because when I look at people tests on the Model 3 they get 73Kwh on a battery of similar size (75? 80?)

 

[AlanSubie4Life]

The trip meter also isn't 100% accurate. You can't use the number it reports to determine the size of your battery.

Yes, I have found that it can be up to 3-4% off (based on amount of energy put back in the battery, extrapolation to 100% discharge, etc. - it's hard to determine the precise amount of error because there are a lot of moving parts). The exact error quantity and when the error is largest, I don't know.

 

[fbitz777]

Yes, I have found that it can be up to 3-4% off (based on amount of energy put back in the battery, extrapolation to 100% discharge, etc. - it's hard to determine the precise amount of error because there are a lot of moving parts). The exact error quantity and when the error is largest, I don't know.

Well maybe but ALL my tests have been 100 percent to 0 percent and back.

 

[AlanSubie4Life]

I NEVER have gotten more than 65Kwh even on a NONSTOP trip from 100 to 0% and that was on a warm day driving close to rated.

there is definitely something not accounted for in the 75XD model because when I look at people tests on the Model 3 they get 73Kwh on a battery of similar size (75? 80?)

Yeah, probably not valid to compare between Model S & Model 3. The accuracy of the meters may not be the same for whatever reason.

The one time I did a valid test on a Model 3, my full discharge extrapolated to 73kWh (this was a ~59.5kWh draw for a 91%-10% discharge). Don't remember the exact numbers but I have a picture somewhere.

Obviously there is room for error in the extrapolation due to voltage non-linearities in the SoC tracking, etc. It can only be so good.

In the end it's a meter and it may not reflect the actual use of energy. In the end, of course, it may mean that it makes your efficiency look better. The only thing that actually matters is how many miles you can go, of course. And that may well be a problem as well.

For you, since you're putting in 77kWh per full charge, your battery certainly does not have 75kWh of capacity. (Probably more like 67kWh if the charging efficiency is the same as the Model 3.)

 

[Dr. J]

There's also the matter of battery degradation which could shave off 5% or a little more on a less-than-new car compared to a brand new car.

 

[fbitz777]

In the end it's a meter and it may not reflect the actual use of energy. In the end, of course, it may mean that it makes your efficiency look better. The only thing that actually matters is how many miles you can go, of course. And that may well be a problem as well.

For you, since you're putting in 77kWh per full charge, your battery certainly does not have 75kWh of capacity. (Probably more like 67kWh if the charging efficiency is the same as the Model 3.)

You are right my car has degraded over two years from 237 to 222 now (7%) so close to 70KWh.

Also note that there is a 5% bottom buffer built in...many times I am able to run 12 miles past zero (I run these tests so I am never far from the charger and look for the energy graph carefully)

 

[fbitz777]

OOPS sorry guys I thought we were talking about the X75 car and noticed this is a model 3 thread ....I thought the Model 3 LR battery size was never revealed but should be closer to 80KWh?

As an example my Bolt is a 65KWh battery and I routinely get 61KWh.

 

[jsmay311]

As I mentioned I get the fact that there is vampire drain etc. but a 20% lost......consistently?

You didn’t answer any of the questions that would help assess this.

Regardless, the few instances where I’ve noted kWh usage after driving a long distance starting with a full charge, the kWh used number and the percent remaining on the battery gauge extrapolated out to 68-70kWh of usable battery capacity. So idk why we wouldn’t see higher kWh figures.

 

[Dan123]

I understand that and get the losses from pre-heating and the vampire drain but I doubt that accounts for me being over 10kw short on each cycle.

How many days in between your charges? You are going to be losing 500wh - 1kwh daily.

 

[Ninetenjack]

How many days in between your charges? You are going to be losing 500wh - 1kwh daily.

Sometimes its 3 days and sometimes its 1 day between charges, my issue is not with the lost but the consistency of always being roughly 10 kWh short....

 

[diamond.g]

You guys need this (I plan on ordering one myself, just to have). EVTV Motor Verks Store: Tesla Model 3 CAN Monitor, OEM Electric Vehicle Items, TeslaModel3CANKit
Basically Jack R says that the car lies to you and that if you really want to know the capacity you have to ask the BMS.

 

[AlanSubie4Life]

Sometimes its 3 days and sometimes its 1 day between charges, my issue is not with the lost but the consistency of always being roughly 10 kWh short....

Again, hard to say, but breaks down as:

• Driving use (may be inaccurately metered by a few %)
• Use while in Park, or just with car door open and not in car, or preheating (not counted on the meter) -> Preheating can easily use ~1kWh in 10 minutes
• Vampire drain - will be 750Wh to 1kWh per day

So you can do a trial experiment IMMEDIATELY after a charge and do a reasonable length drive (say 40 miles or more), and do:

(Starting rated mi - Ending rated mi ) * 242Wh/mi (if you have RWD with latest firmware you may want to use a smaller number like 230Wh/mi - I am not sure what the situation is there though!)

• Starting rated mi -> recorded immediately after putting car in drive
• Ending rated mi -> recorded immediately before putting the car in park at destination.

And then compare this result to the trip meter Wh/mi * miles, for the same trip, recorded immediately after putting car in park.

Be sure not to spend any time in park during the journey.

Then see how far off that is. I'd expect within 5% (which would be 3.5kWh error for a full discharge).

 

[jsmay311]

(Starting rated mi - Ending rated mi ) * 242Wh/mi (if you have RWD with latest firmware you may want to use a smaller number like 230Wh/mi - I am not sure what the situation is there though!)

The “rated” line on the energy graph in my RWD LR was unchanged before/after the latest software update that increased the displayed range. It was 239 Wh/mi before and after.