Decreasing rated range.

[magnet]

I am certainly aware of the cell degradation curve with respect to cell voltage. Being at 100% charge or a 0% charge gives the most cell degradation with respect to time, so yes you are correct in that you don't want to leave your battery like this for any longer than you need to. The times when you need to do this is when you need the range and when you want to balance the battery to maximize potential range. I wish I could fully balance the battery without having to do the 100% charge, but its what it is. I have had success doing "short" balances, just going to 100% then quickly bring it back down. But in my experience the most effective balancing was done as an "overnight" or at least an hours long session at 100%. Especially if the battery is way out of balance. Also keep in mind 100% charge is probably only around 4.1 Volts to 4.15 volts at the cell. I believe Tesla doesn't ever go to a true 100% 4.2 volts during charging (it may get that high during regen after doing a range charge). The only other thing I will say is I have been doing many range charges and long balancing sessions. I have over 30K miles on my original battery. I still get 209 miles rated range.

Edit: I will also mention that high temperature + high cell voltage is extra bad. So when I do the "overnight range charge" session I make sure I do it on a cold battery. My car in my garage sits at a stable 63 F (garage is built into the basement of the house), so this helps.

I wonder if Tesla is changing the reserve capacity over time? They wouldn't do that would not do that would they? Like sell you a bigger pack but only give you access to some of it? What if 0 miles means 10 kWh on a new pack but they next year it means 9kWH. To the user they would see "no degradation"

NCA cells degrade to 75% after a few years and then take another 20 years to get to 70%. Now what if we only ever had access to 85% of the pack? Shoot after 8 years I might still be at 90% of my original range....We know a range charge is a military charge at 4.15v per cell but do we really know what 0 miles means?

 

[ACDriveMotor]

My first thought is that I would applaud extra hidden capacity to minimize (or eliminate) my observable degradation.

 

[InTheShadows]

20k miles.
267 rated miles at a supercharger. (I had 268 two days before at our house when we charged for our trip)
9 months of ownership
Software 5.11
D battery pack

 

[johnmodels]

I'm with you guys. I have 31,000 miles, latest firmware, max range charge is about 250 miles. I haven't balanced the pack ever. A pack.

Thoughts on this anyone???
John

I'm at 25k and 18 months and I think it was 252 last time I range charged. I suppose that about within expectation if I should expect 80% capacity after 100,000 miles.

 

[apacheguy]

Has anyone with any mileage on a D battery seen less than 250 on a range charge? My guess is not, but I would love to be proved wrong.

250 rated. 36,000 miles. A pack.

 

[Super Gizmo]

A pack. Until about 14K miles I used to get around 245 miles for max Daily and around 265 for max Range and then it dropped to 213-214 for max Daily and 245 max Range. After a firmware upgrade the max Daily went up to 225 and max Range to 250 but recently the maxDaily has dropped back down to 220. I haven't done a Range charge in a while. I usually charge in the middle of the Daily range. this is very disappointing because Tesla tells me this is normal. The car now has about 23K miles. How can it be normal when some people get 265 miles with the sam number of miles on their car while others get 245 - 250.

 

[glhs272]

A pack. Until about 14K miles I used to get around 245 miles for max Daily and around 265 for max Range and then it dropped to 213-214 for max Daily and 245 max Range. After a firmware upgrade the max Daily went up to 225 and max Range to 250 but recently the maxDaily has dropped back down to 220. I haven't done a Range charge in a while. I usually charge in the middle of the Daily range. this is very disappointing because Tesla tells me this is normal. The car now has about 23K miles. How can it be normal when some people get 265 miles with the sam number of miles on their car while others get 245 - 250.

My guess is the variability of a max range charge from one car to another is due to usage conditions and possibly battery version (A vs. D packs). I am guessing the Rev D packs might have slightly better chemistry and/or BMS that keeps the range higher for longer. Also, the cars that see more frequent range charges and complete battery draw downs end up having their batteries better balanced. This means they will likely see higher rated range when they do a max charge. However I suspect these same cars will likely see real degradation faster than the cars doing shallow charge cycles and less frequent range charges. These cars are most likely showing steep degradation only due to battery imbalance. But in order to see a true long term difference between these usage cases we need to see a lot of cars with over 100,000 miles.

In my case I am combining semi-frequent range charges and deep charge cycles (monthly road trips) with mostly shallow depth of charge and an 80% charge setpoint (daily driving). This seems to work well for showing a high rated range for a long time with lots of miles on my car.

You could prove me wrong by doing some battery balancing and seeing no benefit. But if you haven't been doing any balancing and doing a lot of sub 90% charging, then your range issue will likely see improvement with balancing.

 

[InTheShadows]

I usually do at least one range charge per week, sometimes two or three because of how far I have to drive per day. Our car is never set below 90%.

I almost always get back with at least 50-70 miles left. I'm thinking about not doing a range charge for one of my long days this week so I run the pack down to the sub 30's. The last time our car was below 30 miles of range was early February.

 

[Denarius]

I just broke 30,000 miles and my last range charge was 254. B Pack.

 

[dirkhh]

21k miles. 204 mikes on a range charge this morning (obviously a 60)

 

[qwk]

When you guys report these range charge numbers, is the car in range or standard mode? FYI, there is a 2-3 rated mile difference.

 

[David99]

Just a reminder that you can't use the number of miles shown to determine battery degradation or capacity. I had situations where I, after finished charging, drove for 5 miles (not downhill) before the number started dropping at all. I had situation where I started driving after charging and it dropped 4 miles right away. These numbers are based on a mathematical model that tries to consider a lot of factors. It is not an actual gauge for how much energy can be stored in the battery.

A better, even though not perfect method, is to charge the car to 100%, then drive it down to 0 and look at the trip meter to see how much energy has been used. On my almost new S85 I got 76.5 kWh. Which is, interestingly enough, exactly 90% of the total capacity. The car will allow you to keep driving to go down another 5% then shuts down and keeps the last 5% as 'brick protection'.
This method doesn't work if you drive it like crazy, though. The discharge rate is important for the total capacity. The faster you discharge, the more losses inside the battery which gives you a lower total energy output.

 

[DriverOne]

21k miles. 204 mikes on a range charge this morning (obviously a 60)

Fantastic. I've got 18K miles and I doubt I'd reach 200.

 

[mknox]

FWIW, I am now getting 214 miles @ 90% (85 kWh A pack) with about 32,000 miles.

 

[donv]

My S85 still shows 232 when charged to 90%, with 15,000 miles (delivered end of June, 2013).

 

[AmpedRealtor]

In March, at about 8,000 miles my ideal range at 100% charge was 301 miles. Today, at about 13,000 miles my ideal range at 100% charge is 289 miles. Service advised that this variation is normal and not representative of any change in the battery's condition. I am one of those who rarely goes to the extremes and typically use my battery in the 30%-70% range.

Oh well.

 

[FlasherZ]

Roughly 15,000 miles on my replacement/refurb rev. D pack (previous mileage prior to refurb unknown). Car charges to 266 trip mode, 239 at the 90% "divot" in the charge bar.

 

[ckessel]

Roughly 15,000 miles on my replacement/refurb rev. D pack (previous mileage prior to refurb unknown). Car charges to 266 trip mode, 239 at the 90% "divot" in the charge bar.

Man, I'm really started to feel earlier buyers got shafted on degradation....

 

[AmpedRealtor]

Man, I'm really started to feel earlier buyers got shafted on degradation....

I don't think this is necessarily true. For instance, there is no way that I experienced 4% degradation 5 months and 7,000 miles after doing my first 100% charge in March. I have a B pack. When I max charged a few days ago, the display showed 289 miles but the car continued charging for a good 30-40 minutes after it hit 100%. That current went into the pack even though the miles didn't increase beyond 289, so there is more charged capacity than the display is showing. The first time I max charged in March, I could drive 11 freeway miles before the display dropped by 1 mile. After max charging a few days ago, I immediately lost range as soon as I started driving.

The algorithm seems to be pretty wonky and unreliable when it comes to determining actual pack capacity.

 

[Cottonwood]

At 24,000 miles and 2 years, on the original A pack, I get 255 range miles on a 100% charge. If I do a few 100% charge, more than 50% discharge cycles on a trip, I can occasionally see 256 range miles.