For those owners unhappy with drop in maximum charged range

[techmaven]

And it doesn't matter to me if it is a software or hardware problem. The miles ain't there anymore - that is all that is important.

Definitely Tesla needs to respond to this. I'm definitely curious if the problem is that the BMS is defining 100% for you at lower and lower amounts (software bug). It would seem to me that if they do a centering calculation, the BMS should always define 100% capacity such that a 40 kWh owner never sees any degradation until the 60 kWh pack cannot hold 40 kWh anymore.

I do wonder how many issues the Tesla engineering team is fighting - with so many cars in so many new situations, they may be really stretched right now. It would seem to me that the easiest solution is to give you a temporary 60kWh upgrade until they can sort their software out. Or at the very least, bump a software rev that redefines the 40 kWh as say, 50 kWh for a bit and then later sort out the BMS.
:smile:

 

[hans]

I feel like the range on my 60 didn't really start "degrading" until I started to baby the pack by only charging to 67% each day. Basically I limited my 60 to the normal behavior of a 40 that charges to 100% and it appears I ended up with the same result because my 100% charge is now 191 rated miles instead of 207. I still believe that the range is not really gone and that the pack is just out of balance. However I am unable to get the pack back into balance and I have tried several ways to get that done. For example, running the battery low and then charging all the way back to 100%. I have tried trickle charging on 110VAC. I have tried charging to 90% every day for several days in row. I refuse to try to charge it to 100% and leave it there for a long period of time because that would not be good for the pack and the whole point of me "babying" it in the first place was to increase the longevity of my battery. Anyway, my car is in the service center and this "degradation" issue was one of the items I asked them to address. It will be another week before I get the car back because I am out of the country buy it will be interesting to see what they say. I do believe that they will be giving us some new firmware that does a better job of keeping the pack in balance and then all the range will be restored. Fortunately I don't need the last few missing miles at the moment but I can see how this would be a major inconvenience for anyone that does.

 

[stopcrazypp]

I refuse to try to charge it to 100% and leave it there for a long period of time because that would not be good for the pack and the whole point of me "babying" it in the first place was to increase the longevity of my battery.

If you refuse to do this, your pack will never be balanced. The balancing cycle happens after your car is fully charged and sits plugged in at 100% (at least for a couple of hours). Trickle charging, charging to 100% and then unplugging, and charging to 90% does not balance the Model S pack. It might have worked on the Roadster pack, but it doesn't appear to work with the Model S (haven't seen any reports of people successfully balancing their pack without leaving the car plugged after a 100% charge).

Since it appears to worry you a lot, I suggest you do this once just to get confirmation it works.

 

[NeedToDrive]

markb,

How long have you had your car? This doesn't sound universal. Although I am concerned about a drop in charge, my 40kwh has dropped to 136 rated miles when I do a full charge -- which is very infrequent. Normally I have the slider set so it only charges to ~95 since my daily commute is ~10 miles. I have a little over 3000 miles and have had it almost one year (I think I was among the first to get one). In that time I've only been close to less than 15 rated miles two, maybe three times -- mostly I've been above 70 rated miles.

My concern really lies in how the software limits the battery to 40kwh. At one point I was told that 1/3 of the battery was cut off. I knew that couldn't be the case since my SW limitation actually happened with a new update (That's right I had the benefit of a 60kwh for a week). Later this was clarified that the computer calculates a maximum percent of the SOC. In any case, obviously SW is the key. If Tesla wanted to, when the slider is at max, they could just have the SW charge to a fixed rated range (say 140 miles).

 

[hans]

If you refuse to do this, your pack will never be balanced. The balancing cycle happens after your car is fully charged and sits plugged in at 100% (at least for a couple of hours). Trickle charging, charging to 100% and then unplugging, and charging to 90% does not balance the Model S pack. It might have worked on the Roadster pack, but it doesn't appear to work with the Model S (haven't seen any reports of people successfully balancing their pack without leaving the car plugged after a 100% charge).

Since it appears to worry you a lot, I suggest you do this once just to get confirmation it works.

I do charge to 100% and let it go until 'Charge Complete'. The balancing is supposed to happen during the long period at 99-100% After that I drive. No reason to let it sit. If the car is not charging its not balancing correct?

 

[jerry33]

I do charge to 100% and let it go until 'Charge Complete'. The balancing is supposed to happen during the long period at 99-100% After that I drive. No reason to let it sit. If the car is not charging its not balancing correct?

Maybe. It could also be that the majority of the balancing is done at the 1 minute left mark but balancing continues as long as the LEDs are green. I don't know this for a fact, just suggesting that it's a possibility as some have reported seeing 1 amp at this time.

 

[dhrivnak]

If the car is not charging its not balancing correct?

Not true in a Roadster. Balancing takes time and you have to let the car sit at a high state of charge for the balancing to occur. It looks at the voltage of each brick and equalizes the pack and you do not need to be plugged in for this to happen. If you start driving the voltage will drop and the bricks never have time to equalize.

 

[stopcrazypp]

I do charge to 100% and let it go until 'Charge Complete'. The balancing is supposed to happen during the long period at 99-100% After that I drive. No reason to let it sit.

The balancing happens AFTER 100% charge. Here's the part describing a successful balance:
http://www.teslamotorsclub.com/show...ed-range/page6?p=386370&viewfull=1#post386370

Basically it seems the car is charged until the charge port stops blinking (which usually indicates charging is finished). However, if you leave it plugged in, it keeps charging (over an hour) and this is when balancing happens. I'm not sure if the 99-100% period you are talking about coincides with this. He also did it with a 110V, but I think it only matters near the end (example used 240 volt up to standard charge and then 110V to range change).

If the car is not charging its not balancing correct?

Depends on what you describe as charging. The car might not indicate it is "charging," but it should still be pulling current from the charge port (unless there's active balancing where energy is moved from the strong cells to weak cells rather than bled off, or as dhrivnak says, it just equalizes the cells rather than getting all of them fully charged). The thing to note though is that it's been confirmed the Roadster can still balance the pack without being charged to 100%. I haven't seen any case where the Model S can balance without being charged to 100%.

Balancing in layman's terms is after reaching "100% SOC," you have to bleed off the energy in the strongest cells and continue to charge the weakest cells in the pack. Depending on how out of balance your pack is, it may take a while.

Regardless, letting the pack sit plugged in a couple hours at 100% just as a trial doesn't really hurt it much. You should see an increase in your range number (from your previous peak, which you indicate as 191 miles) as this is happening if the balancing is working.

 

[aaron0k]

Same issue and concern, you can add me. I'll PM you my email.

I went from 140 to 125 on my 40 kwh. Tesla rep told me the car has just been adjusting to my driving habits. I mentioned it only went lower with recent updates.

 

[markb]

markb,

How long have you had your car? This doesn't sound universal. Although I am concerned about a drop in charge, my 40kwh has dropped to 136 rated miles when I do a full charge -- which is very infrequent. Normally I have the slider set so it only charges to ~95 since my daily commute is ~10 miles. I have a little over 3000 miles and have had it almost one year (I think I was among the first to get one). In that time I've only been close to less than 15 rated miles two, maybe three times -- mostly I've been above 70 rated miles.

My concern really lies in how the software limits the battery to 40kwh. At one point I was told that 1/3 of the battery was cut off. I knew that couldn't be the case since my SW limitation actually happened with a new update (That's right I had the benefit of a 60kwh for a week). Later this was clarified that the computer calculates a maximum percent of the SOC. In any case, obviously SW is the key. If Tesla wanted to, when the slider is at max, they could just have the SW charge to a fixed rated range (say 140 miles).

If you have only 3000 miles on your car, that may be why you haven't seen much reduction in range. I have over 9000 miles - my first drop in range also brought me to around 136, as I recall. The fact that you are still at 136 and others below 120 kind of negates the theory that the reduction is due to software changes, a very popular theme on the official Tesla forums.

I put a deposit on my car in 2010 - I took delivery in May, also one of the first to do so.

- - - Updated - - -

I feel like the range on my 60 didn't really start "degrading" until I started to baby the pack by only charging to 67% each day. Basically I limited my 60 to the normal behavior of a 40 that charges to 100% and it appears I ended up with the same result because my 100% charge is now 191 rated miles instead of 207 .

That is interesting and really does imply that the loss is due to consistent, partial charging.

 

[hans]

I monitor my car very closely using the REST API and some logging programs. I do not believe I have ever seen the car draw shore power after entering 'charge complete' state except for HVAC. If the pack is balancing without pulling shore power then it shouldn't need to be plugged in, but it would need to sit unused. I know I have done a complete charge and let it sit an hour once, but only ever once. It wasn't enough to increase my estimated range but others have reported needing to do this several times to have a n effect

 

[qwk]

I do charge to 100% and let it go until 'Charge Complete'. The balancing is supposed to happen during the long period at 99-100% After that I drive. No reason to let it sit. If the car is not charging its not balancing correct?

It's easier to leave your car unlocked(while charging), in order to understand this better. Monitoring with the app leaves a bunch of info out. When the car is charging(regardless of mode), the charge port pulses, and the dash is on. When the car finishes the charge, and is balancing, the charge port stops pulsing, but is still on, and so is the dash(voltmeter on dash pulses, meaning the battery is being balanced). When the balancing is done(takes 5-90 minutes), the car goes dark.

 

[dhrivnak]

On the Roadster you do not need to be plugged in to balance but you do need to let the car sit at full charge. Also you may be seeing the "winter" effect. Below if a graph of ideal miles from my Roadster. Notice that my "range" drops to about 172 in the winter but is about 178 in the summer fall. I have seen this now for 3 seasons. So I would wait for summer before getting too worked up.

 

[NeedToDrive]

and others below 120 kind of negates the theory that the reduction is due to software changes, a very popular theme on the official Tesla forums.

To be clear, I'm not suggesting that subsequent SW changes are the cause. It's the original implementation that I'm fingering. Recall that this had to be implemented very quickly and I don't think anyone had much time to really think it through. Reading about your experience does make me worry that something fundamental is going on. I wonder, can you plot your maximum achieved charge over time? Is it smooth or does it move around a lot (with a general decreasing value)? When do you look at the final number? Is it just after charging is complete or some time later (i.e. the next morning)? I have my car set to start charging at 2:00 AM and notice that there is a reduction by the time I get to the car in the morning (but nothing near 16 miles).

One of my worries is how the 40kwh algorithm tests when the charge is complete. If it is measuring the SOC and comparing to some fixed allowable (as one service person explained to me), then that measurement is key. I rather suspect that this measurement is hard to make and not perfectly accurate. In fact, it may be just the opposite - a somewhat noisy measurement. Though, again, your experience is too large a deviation to be explained by this.

Since this is happening to many folks I recommend that the SW for the 40kwh be updated to use the calculated rated range while charging and compare that to a fixed allowable of 136. This wouldn't be hard to implement and would certainly fix the problem. It would also have the effect of counteracting problems due to an inability to load balance (I didn't know that one needed to be at full charge for that to occur). Of course, it would also have the added benefit of hiding any degradation of the battery.

 

[Ocelot]

This thread makes me support batter swapping even more. While I seem to be in the deep minority here on TMC, i much rather not deal with any of this stuff. I want to buy the car and lease the battery. I do not want to baby it, worry about it or experience real or imagined issues. i do not want to spend hours planning a trip around superchargers, and buying multiple coffees until it is finished.

In the OP's first post a battery swap would mean, just leaving Tesla with the battery to balance...configure whatever, and him driving off happy after 2 minutes.

 

[markb]

I wonder, can you plot your maximum achieved charge over time? Is it smooth or does it move around a lot (with a general decreasing value)? When do you look at the final number? Is it just after charging is complete or some time later (i.e. the next morning)? I have my car set to start charging at 2:00 AM and notice that there is a reduction by the time I get to the car in the morning (but nothing near 16 miles).
.

No, can't plot my max charge over time - haven't been keeping those kind of records. It seems to drift down and then to plateau for a while - as I recall, my first plateau was at 136 or so. And I have been checking my range immediately after charging completes.

 

[eAdopter]

I've been reading about these concerns for a while, but wanted to gather data before posting.
My 40 began life June 3, 2013 with 144 Rated miles. In July the battery failed and was replaced. The new battery charged to 147 Rated miles.


I've been tracking Rated and Ideal miles since June. Both have been on a steady, almost linear decline.


Today, Rated is at 125. However, that doesn't tell the whole story. Drivable miles are worse than that:


In late August, the Rated miles were 142 and I tested the car. I drove it 141.5 miles - all the way to zero plus an extra half-mile to get home. This test demonstrated that the Rated calculations were very accurate for real-world driving. Note that the test was all highway driving at a near-steady 62 mph.


Today I tested the car again. The Rated 125 only provided 102 (!) miles, again driving all highway miles at a near-steady 62 mph. Same route as before.



I recognize these two tests are different. In August the A/C was on with Temp set to 68 (a hot day). Today the heater was on with Temp set to 74. I'm not sure which one (heat or A/C) uses more energy in my Model S, but in my ICE vehicle the A/C uses more. Also, I assume in summer that the battery requires some cooling. In winter, not as much. For now I'll assume conditions to be "similar" until I learn otherwise.


In summary, like markb, my 40 has experienced significant range reduction from 142 to 102 drivable miles. I'm concerned. However, I also recognize this is a very easy situation for TM to remedy due to the extra/unused capacity of a 40. My hope is that TM will make it right. We'll see.

 

[huntjo]

I've been reading about these concerns for a while, but wanted to gather data before posting.
My 40 began life June 3, 2013 with 144 Rated miles. In July the battery failed and was replaced. The new battery charged to 147 Rated miles.


I've been tracking Rated and Ideal miles since June. Both have been on a steady, almost linear decline.


Today, Rated is at 125. However, that doesn't tell the whole story. Drivable miles are worse than that:


In late August, the Rated miles were 142 and I tested the car. I drove it 141.5 miles - all the way to zero plus an extra half-mile to get home. This test demonstrated that the Rated calculations were very accurate for real-world driving. Note that the test was all highway driving at a near-steady 62 mph.


Today I tested the car again. The Rated 125 only provided 102 (!) miles, again driving all highway miles at a near-steady 62 mph. Same route as before.



I recognize these two tests are different. In August the A/C was on with Temp set to 68 (a hot day). Today the heater was on with Temp set to 74. I'm not sure which one (heat or A/C) uses more energy in my Model S, but in my ICE vehicle the A/C uses more. Also, I assume in summer that the battery requires some cooling. In winter, not as much. For now I'll assume conditions to be "similar" until I learn otherwise.


In summary, like markb, my 40 has experienced significant range reduction from 142 to 102 drivable miles. I'm concerned. However, I also recognize this is a very easy situation for TM to remedy due to the extra/unused capacity of a 40. My hope is that TM will make it right. We'll see.

In your ICE car the heat uses less energy cuz it takes advantage of the waste heat from the IC engine. In Model S, cold weather affects range way more do to both the heater uses as well as battery pack warming to keep it in the "sweet spot" temperature for charging/ discharging.

 

[stopcrazypp]

In late August, the Rated miles were 142 and I tested the car. I drove it 141.5 miles - all the way to zero plus an extra half-mile to get home. This test demonstrated that the Rated calculations were very accurate for real-world driving. Note that the test was all highway driving at a near-steady 62 mph.

You can't do a linear mapping of rated miles to miles you get because the miles under zero are not factored in. There was a long thread discussing the right formula to use. You also have to monitor your actual Wh/mi usage in order to get a decent estimate.

I recognize these two tests are different. In August the A/C was on with Temp set to 68 (a hot day). Today the heater was on with Temp set to 74. I'm not sure which one (heat or A/C) uses more energy in my Model S, but in my ICE vehicle the A/C uses more. Also, I assume in summer that the battery requires some cooling. In winter, not as much. For now I'll assume conditions to be "similar" until I learn otherwise.

The heater uses more energy in an EV because there is little to no waste heat from the motor (unlike an ICE, which has plenty of waste heat). The battery doesn't need to be cooled in the winter, but it needs to be heated. Also a cold battery has less apparent capacity than a warm one. And depending on how cold the temp is, the resistive part to the heater might turn on (which is 3x less efficient in providing heat/cold air than the heat pump heater and general AC).

Air resistance and rolling resistance also increases in cold temperatures which will drop your car's efficiency even if you don't use the heater (and also if none of the above effects applied).

 

[markb]

@eadopter, have you found the calculation of projected range has changed? Before 5.8, my projected matched rated at approx. 305 wh/mile. Now, my wh/mile needs to drop to 280 for them to match. So while my rated and ideal range has dropped significantly, my projected range has dropped even faster and further