90D Range slowly declining

[msnow]

Good question. It's complicated. A new battery will lose capacity the quickest. So some of it is the battery "settling" which will resolve itself in a few months. If it continues to drop at the same rate, something's wrong.

It also depends on how the pack is cycled. Plenty of evidence shows that charging to 60 or 70% daily will cause the range also to "lose sight of 100%" and it will err on the conservative side and underestimate capacity.

Day to day variations should not be large. In my experience, it is accurate to +- 1 rated mile.

Makes sense, thanks.

 

[Joe Harsanyi]

My p85d is 7 months old with 12k miles. Rate at 90% shows 226 and at 100 shows 253.

Those were the numbers I had up to about 3500 miles.........do you think your driving/charging behavior is keeping you in this like new state, or are you just fortunate?

 

[gimmi80]

I've got my 70D in May with 234 miles @100%
It has been stable around that value for the first 3-4 months.

I frequently do 100% charges (at least once a week) but I used to time it so that it was done right at the time I was leaving for the commute.
Lately I became more lazy and I just plug it in in the evening and let it sit @100% for a good 6-8 hours, until the morning.
And I've noticed that... the 100% charge went up to 238 miles
I assume battery pack needed to balance itself.

I do at least a 100% charge each week (for a long commute) Supercharge at least twice a week (same long commute).

 

[Panoz]

Geez Louise...I was hoping my dry sense of humor was evident. I'm the guy that said he was going to sell his car because I had 2 miles less at 90% charge.

I am NOT selling my car! I was poking fun at folks that are what I call "clock watchers". A watched pot will never boil, and a Tesla battery, if checked daily for range, will never satisfy the owner.

I love my car. Range will vary every day due to a host of factors, not the least of which is a software update. Enjoy your cars and take my comments with a grain of salt. I'm a funny guy!

 

[sorka]

Those were the numbers I had up to about 3500 miles.........do you think your driving/charging behavior is keeping you in this like new state, or are you just fortunate?

It's hard to say. At 80% and 90% I'm 1 mile down from what I was when it was new and this only just changed about 2K miles ago.

Most of my driving commuting which is 130 miles each way. I generally range from 85% down to 33% or 90% down to 38%.

So I was expecting a larger than average decline and I guess at this point it's clear that it's less.

Still, the loss that the 90 batteries are experiencing seems higher than what the 85 batteries did.

I've been warning about what LiIon silicon anode chemstry has typically meant in the industry since they first annoucned the 90 battery:

I'm not sure how you're supporting your conclusions and I won't came right out and tell you that you're wrong without you first backing it up.

Silicon in LiIon battery anodes increases capacity at the expense of decreasing maximum C rate because Si increases internal resistance. Hobbyists know this because when they pick cells that have higher capacity due to Si, the maximum rate of discharge is lower. In addition, the cycle life with Si anodes is lower as well. These are the tradeoffs and you pick the cell that suits the application.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120012917.pdf

"Impedancespectroscopy measurements further demonstrate that the cell with the Si anode has a higher initial resistance than the cell with the graphite anode, and the SEI formation results in an increase in the cell internal resistance for both the Si and graphite anodes. "

This doesn't mean that the new cells haven't had this problem solved or that there was some other magical additive that to solve this issue, but with what we know now we can't assume that the performance of the battery cells are improved. It could just as well be that the 2/0 copper spine in the battery which already wasn't sufficient to handle 1300 amps was upgraded to a larger size conductor but that component of the battery is not accessible for replacing.

That was a rumor. Also additives like silicon that increase how many Lithium Ions that anode can absorb tend to increase impedance. The price for increased capacity is often decreased maximum current. So if they didn't manage to increase the impedance of the new cells with Silicon, they must have discovered something revolutionary to get around it which is quite possible.

Both batteries weigh the same. The only change was very tiny amount of silicon used in place of some of the graphite in the graphite anode which allows the anode to suck up more lithium ions.

That said, silicon is know to reduce cycle life of Lithium Ion batteries. The maximum current shouldn't be any more on the 90 as that's not an advantage of silicon, but we don't know that they didn't make any other changes and even if both pull the same maximum current at 100% SOC, the voltage will be higher on the 90 battery after both have traveled x miles since the 90 will have a higher SOC than the 85. So it's fair to say that all being equal, the 90 will put more power down than the 85 after both have traveled 50 miles...as an example.

 

[fieldalias]

Mine started out with 251 at 90% and now is about 250. I drive aggressively
90D as well.

 

[rjcbox]

My guess is due to algorithm calc/pack balancing, rather than true accelerated degradation. Time will tell. In the meanwhile, hope you enjoy the heck out of it. I certainly am

 

[rawn77]

So I started this thread, complaining that my 90D's 90% was at 251, down from 257 when delivered at end of September.
This morning I'm at 250; seems to be degrading at the same curve; about 1% per 6 days.
Not very happy to say the least.
Ron

 

[Panoz]

Mine is down a few miles, too. If you're really concerned (I'm not), charge to 95% today, 80% tomorrow, then back up to 90% and take a reading.

 

[apacheguy]

So I started this thread, complaining that my 90D's 90% was at 251, down from 257 when delivered at end of September.
This morning I'm at 250; seems to be degrading at the same curve; about 1% per 6 days.
Not very happy to say the least.
Ron

What's your daily DOD (depth of discharge)?

Have you ever 100% charged?

 

[msnow]

If DOD is the difference between the range rate before and after 90% charge. Mine started at 257 on day after delivery and is now 252, about 5 miles loss in a month.
I have charged to 100% once 2 weeks ago.

 

[rawn77]

What's your daily DOD (depth of discharge)?

Have you ever 100% charged?

I usually drive about 75 miles per day and yes I've charged to 100% about 5 times; all when taking a long trip

 

[apacheguy]

I think there are enough threads on this issue to merit a blog post response. Tesla must have mounds of data collected both internally as well as through the fleet of cars. A simple chart breaking down capacity v # of cycles by geographical region and battery pack type would go a long way toward reducing owners' degradation anxiety.

 

[SkinnyWeasel]

So here is a question for the group! I am experiencing same as original poster but I started much lower. P90D delivered September 29th with 90% charge of 241. I am at 235 in a month. Still, I started much lower than these other P90D owners. Anybody know what the acceptable variation is and whether I should have had another 10 or 11 miles of rated range to start? Live in Chicago and drive very few miles. Some days zero, some days 30. Done one supercharge and one charge to 95% for road trip. Any thoughts? Should I call service? Never really thought about it until I was all the posts with 85 owners with similar range as me and 90s with higher range. Thanks!

 

[msnow]

So here is a question for the group! I am experiencing same as original poster but I started much lower. P90D delivered September 29th with 90% charge of 241. I am at 235 in a month. Still, I started much lower than these other P90D owners. Anybody know what the acceptable variation is and whether I should have had another 10 or 11 miles of rated range to start? Live in Chicago and drive very few miles. Some days zero, some days 30. Done one supercharge and one charge to 95% for road trip. Any thoughts? Should I call service? Never really thought about it until I was all the posts with 85 owners with similar range as me and 90s with higher range. Thanks!

I understood these responses to be mostly 90D cars (I could be wrong) which have a higher range than P90D but I think the same logic would apply.

 

[Max*]

So here is a question for the group! I am experiencing same as original poster but I started much lower. P90D delivered September 29th with 90% charge of 241. I am at 235 in a month. Still, I started much lower than these other P90D owners. Anybody know what the acceptable variation is and whether I should have had another 10 or 11 miles of rated range to start? Live in Chicago and drive very few miles. Some days zero, some days 30. Done one supercharge and one charge to 95% for road trip. Any thoughts? Should I call service? Never really thought about it until I was all the posts with 85 owners with similar range as me and 90s with higher range. Thanks!

TM advertises the P85D as 253RM on a 100% charge. They also advertise the 90kwh battery to be 6% more range than the 85kwh battery. So 253*1.06*90%=241RM. So you're rated miles at delivery is valid.

 

[SkinnyWeasel]

TM advertises the P85D as 253RM on a 100% charge. They also advertise the 90kwh battery to be 6% more range than the 85kwh battery. So 253*1.06*90%=241RM. So you're rated miles at delivery is valid.

I understood these responses to be mostly 90D cars (I could be wrong) which have a higher range than P90D but I think the same logic would apply.

Thanks to both. Of course. Now I feel totally stupid. Totally forgot about the 90 vs. P90. Makes perfect sense and math works. So only remaining question is why the degradation over less than one month of ownership. May just call Tesla service to ask. I know a lot of folks say it is normal/driving influences rated miles etc. Just surprised to see those range miles tickin away in one month.

 

[TexasEV]

Thanks to both. Of course. Now I feel totally stupid. Totally forgot about the 90 vs. P90. Makes perfect sense and math works. So only remaining question is why the degradation over less than one month of ownership. May just call Tesla service to ask. I know a lot of folks say it is normal/driving influences rated miles etc. Just surprised to see those range miles tickin away in one month.

Driving does NOT influence rated miles. Rated miles are based on the EPA testing cycle. YOUR mileage varies based on how you drive, just like in an ICE, but your driving doesn't influence the EPA rating.

Your range miles are not ticking away. It's an estimate and the estimate becomes less reliable over time unless your battery is fully charged and fully depleted, which is bad for the battery. So don't sweat a few miles on the display and just enjoy the car.

 

[msnow]

Understood and I'm using the EPA estimate just as a baseline however people paid $3k for a few extra miles that seems to be going away each day. The extended range option was supposed to be roughly 6% more miles and it's slowly eating away at that benefit or at least so it seems. I'll keep track of mine and if it continues to drop will bring it to the attention of Tesla service.

 

[Pete90D]

Can someone with a 90D or P90D try charging to 100% to balance?

Shortly after I had my car I was unable to charge to 100% and my range dropped by a set percentage at both 90% and 99%. And when I say wouldn't charge to 100% I don't mean that I didn't let it sit, I mean that it shut off charging at 99%. I haven't had time to go to the service center to have them check it.