Decreasing rated range.

[ACDriveMotor]

Two month old car, I see a consistent 232 on a 90% charge.

I know this has been discussed elsewhere, but when does re-balancing happen? Does a standard charge to 90% cause re-balancing? I am trying to decide whether to charge 50, 70 or 90 on a daily basis. Worried about imbalance if I live too long in the 50 range - and unsure how to re-balance.

I use about 10 - 20 KWh on a normal day.

 

[tdiggity]

Two month old car, I see a consistent 232 on a 90% charge.

I know this has been discussed elsewhere, but when does re-balancing happen? Does a standard charge to 90% cause re-balancing? I am trying to decide whether to charge 50, 70 or 90 on a daily basis. Worried about imbalance if I live too long in the 50 range - and unsure how to re-balance.

I use about 10 - 20 KWh on a normal day.

Rebalance happens when you do a 100% charge. What you'll see happening is that at the very end, it takes a long time to "top off".

 

[ACDriveMotor]

Darn. I had thought that I heard that re-balance happened at Standard Charge and above. I think I heard that about the Roadster.

I am reluctant to do a Range charge just to re-balance. I guess there is no harm in re-balancing just as a side effect of Range charging when needed - kill two birds with one stone. Or am I thinking about it incorrectly?

 

[djp]

Darn. I had thought that I heard that re-balance happened at Standard Charge and above. I think I heard that about the Roadster.

I am reluctant to do a Range charge just to re-balance. I guess there is no harm in re-balancing just as a side effect of Range charging when needed - kill two birds with one stone. Or am I thinking about it incorrectly?

The Model S is supposed to balance after a standard charge, but based on the experience in this thread it doesn't seem to do a very good job of it! I think Tesla still has work to do on their balancing algorithm, it performs much better on the Roadster.

I agree it's best to do the balancing when you actually need the range. If you're going to let the pack sit at 100%, do it in the winter. Cold temperatures will help protect the cells when they're at high SOC.

 

[apacheguy]

I have changed my view on this whole thing and I believe others are indeed correct that the pack is only balanced on a max range charge. This is evident by anyone who collects remote telemetry from charge sessions. Normally I charge to 80% and the car very quickly enters sleep mode upon charge completion. However, as others have pointed out, the car remains awake and reports "1 min remaining" for quite some time while doing a max range charge even though it has attained 100% SOC.

I don't understand the logic behind this. Why can't the BMS balance the pack at any other SOC? Why must it be set at 100%?

 

[bluetinc]

Perhaps the latest sleep mode has broken this, it's been too cold for me to be doing yard work while the car charges up so I can watch it. In the past, it did balance at other SOC's.

Peter

I have changed my view on this whole thing and I believe others are indeed correct that the pack is only balanced on a max range charge. This is evident by anyone who collects remote telemetry from charge sessions. Normally I charge to 80% and the car very quickly enters sleep mode upon charge completion. However, as others have pointed out, the car remains awake and reports "1 min remaining" for quite some time while doing a max range charge even though it has attained 100% SOC.

I don't understand the logic behind this. Why can't the BMS balance the pack at any other SOC? Why must it be set at 100%?

 

[araxara]

I don't understand the logic behind this. Why can't the BMS balance the pack at any other SOC? Why must it be set at 100%?

I don't know how sophisticated the Model S BMS is, but off-the-shelf BMS systems are often set up to start bypassing a cell when it reaches a predefined voltage. In the case of the Model S battery pack, that voltage would be set to the maximum cell voltage and thus at 100%.

 

[djp]

I don't understand the logic behind this. Why can't the BMS balance the pack at any other SOC? Why must it be set at 100%?

There is no reason the Model S can't balance on a lower SOC.

On the Roadster the BMS charges until the highest brick reaches a target SOC (about 87% for a Standard charge and 95% for a Range charge). It then bleeds off the highest bricks. Balancing happens faster after a Range charge, but it still happens after a Standard charge too.

My take is that the charge slider or sleep mode broke balancing on the Model S, and fixing it is low on Tesla's priority list. I expect a future firmware release will improve the balancing algorithm and help restore range for owners who are seeing a drop in their capacity estimates.

 

[qwk]

My take is that the charge slider or sleep mode broke balancing on the Model S, and fixing it is low on Tesla's priority list. I expect a future firmware release will improve the balancing algorithm and help restore range for owners who are seeing a drop in their capacity estimates.

Bingo. Just like the Roadster gets out of balance if you charge and drive in storage mode, the Model S seems to do a similar thing.

 

[Gear]

My take is that the charge slider or sleep mode broke balancing on the Model S, and fixing it is low on Tesla's priority list. I expect a future firmware release will improve the balancing algorithm and help restore range for owners who are seeing a drop in their capacity estimates.

I really hope you're right, and I believe that you probably are. Range charging from home is pretty useless to me as I live in the mountains, so I'm going downhill as soon as I leave my house. That means I'd have to actually use brakes to keep my speed down and wouldn't be getting the free electricity. In addition, it just means I'd be sitting at a high SOC for that much longer as I arrive at my normal destinations with only slightly less charge than I left home with.

 

[brianman]

I expect a future firmware release will improve the balancing algorithm and help restore range for owners who are seeing a drop in their capacity estimates.

Prediction: This will be called 6.1 and owners will rejoice. And then a day later some owner will discover that 6.1 disables something like cruise control or air conditioning. (Poison pill update syndrome.)

 

[Zextraterrestrial]

Prediction: This will be called 6.1 and owners will rejoice. And then a day later some owner will discover that 6.1 disables something like cruise control or air conditioning. (Poison pill update syndrome.)

maybe it will add fake engine noises :tongue:

 

[ACDriveMotor]

Prediction: This will be called 6.1 and owners will rejoice. And then a day later some owner will discover that 6.1 disables something like cruise control or air conditioning. (Poison pill update syndrome.)

Wow, where is the more positive BrianMan? I remember when I was initially pretty down on the air suspension (and rumored regen/accel nerfs) of 5.8. You were a positive or at least objectively reasoned voice. That helped me choose to take a longer term view even as a new owner. Though I am still not happy air suspension was ~2% of my purchase price. Not happy about some of the short-term tactical moves by TM but still love my car.

Now you sound pretty...well jaded. What happened?

 

[qwk]

Wow, where is the more positive BrianMan? I remember when I was initially pretty down on the air suspension (and rumored regen/accel nerfs) of 5.8. You were a positive or at least objectively reasoned voice. That helped me choose to take a longer term view even as a new owner. Though I am still not happy air suspension was ~2% of my purchase price. Not happy about some of the short-term tactical moves by TM but still love my car.

Now you sound pretty...well jaded. What happened?

I think the "A" pack fallout killed a lot of love for Tesla among the Sig crowd.

 

[smartypnz]

Coming up on nine months - 19, 000 miles - range gets 255 - 90% gets 220. 'A' battery end of April delivery.

 

[apacheguy]

I think the "A" pack fallout killed a lot of love for Tesla among the Sig crowd.

Indeed. Obviously I'd still buy a Tesla again, but definitely not a Sig and probably not even an early production model. This whole A pack debacle served as a reality check for me.

 

[FlasherZ]

Prediction: This will be called 6.1 and owners will rejoice. And then a day later some owner will discover that 6.1 disables something like cruise control or air conditioning. (Poison pill update syndrome.)

You must live somewhere near a big software company that tends to do these things. Surprised you didn't say it would be called 8.1 instead.

Did a group of full range charges the other day - delivery 11/26/12, 18000 miles, range charge hits 257. 'A' pack. 90% charge hits 228/229. Charging rate is nearly always 80A.

 

[brianman]

Now you sound pretty...well jaded. What happened?

I think the "A" pack fallout killed a lot of love for Tesla among the Sig crowd.

It's a litany of things. It's difficult to see Tesla as the company that believes that it can and will solve the impossible these days. It has me a bit bummed because basically there's no other game in town, and I know how good the car can be (and future cars) -- but the company is stumbling on stuff that's completely avoidable. Unforced errors are not something you can afford when the deck is stacked against you in so many ways. And if Tesla makes a critical misstep (or a set of them that amount to the same damage) to the point of "game over" for the company, it might be game over for the EV experiment for another decade or two. That makes me disgruntled because I don't want to wait until I'm 90+ to buy a car better than a Model S.

I've been planning to write a "catalog of things that should have gone differently." email and send it to Jerome and Elon but haven't had the time. Not just could but should. Much of the missteps don't take "rocket science" to handle better than they did.

- - - Updated - - -

Surprised you didn't say it would be called 8.1 instead.

I already made that joke about renaming the X in another thread.

 

[dcopperfield]

Indeed. Obviously I'd still buy a Tesla again, but definitely not a Sig and probably not even an early production model. This whole A pack debacle served as a reality check for me.

Yep... 100% agree.

 

[brianman]

Indeed. Obviously I'd still buy a Tesla again, but definitely not a Sig and probably not even an early production model. This whole A pack debacle served as a reality check for me.

Do you mean from a "trust in Tesla" perspective, or from a "dealing with beta/early products generally" perspective?