Actual range of the 160 mile model S

[Robert.Boston]

"Upgrading" the ESS raises other questions: What does one do with a second hand battery pack? Is it worth anything? Will Tesla give me a trade-in value on it?

A little sideways to the topic, but ... these used battery packs should be very valuable on the bulk power system. Adding highly flexible storage will greatly assist with integrating large amounts of variable energy (e.g. wind, wave, and solar). I doubt that Tesla will go into this business, but companies like my client AES Energy Storage are already there.

 

[AnOutsider]

A little sideways to the topic, but ... these used battery packs should be very valuable on the bulk power system. Adding highly flexible storage will greatly assist with integrating large amounts of variable energy (e.g. wind, wave, and solar). I doubt that Tesla will go into this business, but companies like my client AES Energy Storage are already there.

Maybe they'll offer us a discount and then resell the used packs.

 

[Bearman]

A little sideways to the topic, but ... these used battery packs should be very valuable on the bulk power system. Adding highly flexible storage will greatly assist with integrating large amounts of variable energy (e.g. wind, wave, and solar). I doubt that Tesla will go into this business, but companies like my client AES Energy Storage are already there.

There should be some value in the old packs even if just for recycling, current lithium prices are in the range of $4,500 to $5,500 per tonne. But i agree that there should be more value in them as batteries with some capacity left.

 

[brianman]

@VolkerP - Great post. Deep, informative, on point.

 

[richkae]

Hi Rifleman,

A data sheet with Panasonic cell properties was posted here:


Tesla probably uses the CGR-18650CH cell with ~2200mAh for the 40kWh pack. See page 4. The cycle diagram in the lower right corner shows that the cell degrades to 1700mAh after 500 full cycles, that's 77%. Your daily commute of 80 miles would be half a cycle. Two half cycles still are better for battery life than a full cycle. But with 200 work days you rack up 1600 half cycles and 128k miles in 8 years. You pass the battery warranty mile limit at 6.25 years. If you find your battery is at 75% of original capacity then, Tesla would refute a warranty claim by you. If you charge at work, you still can do your commute for many years to come, though.

This datasheet needs more detailed caveats. Those charts show the worst case for battery life. Tesla does not charge the cells as full, nor does it discharge them as deeply. They do this so that you get better battery life than is represented on those charts. How much better is it? We do not know. Tesla tells you that frequent use of range mode ( which does not charge as high as the paramaters of those charts ) hurts the battery life.
It is probably a good idea to look at those charts and use that as a worst case - because it is the only hard data we have, but not to expect that will be the actual performance of the batteries.

I would really love to see the data from a test where the batteries are charged to Tesla's standard charge voltage and then discharged down about 30% 2500 times and compare.

 

[richkae]

You're a Roadster owner, what did they tell you that you could expect when you bought the car?

They were selling Roadster owners replacement battery packs. In order to sell the replacement you would have to tell a customer when and why you would need to replace the battery!? I don't think anyone would buy a replacement battery pack nor do I think Tesla would offer it, if there was only a 1% loss of range after 5, 8 or 10 years.

They set my expectations with what I believe was a worst case ( 30% degradation after 7 years ). I think it is possible that I will need to replace the battery in 7 years and have planned accordingly.
However they provide guidance and say don't use range mode and performance mode too much, don't leave the battery near empty nor near full. I have taken their advice and I only use range mode when I need it, I don't let the battery sit empty or full. It hasn't taken any effort or hardship to do these things that I think will extend my battery life. The evidence so far shows that I am not on a linear path to 30% degradation after 5,7,8,10 years.
Obviously it may not be linear, but at this time it seems likely that it will be significantly better than the worst case.

I'm just trying to say that it is a worst case. Clearly if you need to plan, you should plan for the worst case. We will know more in another 4 years.

 

[dsm363]

I'm just trying to say that it is a worst case. Clearly if you need to plan, you should plan for the worst case. We will know more in another 4 years.

Exactly. For people planning on keeping the car longer than 8 years on the warranty, pick whatever Tesla says is the worst case for the battery degradation and factor that into what battery pack you need for now and the future.

 

[WhiteKnight]

I'm just trying to say that it is a worst case. Clearly if you need to plan, you should plan for the worst case. We will know more in another 4 years.

And to build on what you're saying, Tesla (in factoring in warranty coverage) is definitely going to plan for the worst case and only guarantee 70% after 8 years.

I am glad to hear that your real world experience has been much better than the worst case.

Let's hope we all do much better (although I will be the one stomping it at every stop light :biggrin.

 

[VolkerP]

I agree that the cell cycle diagram is a worst case scenario WRT cycle depth. OTOH Tesla guarantees the 40kWh for 70% after 100k miles, which equals to 625 full cycles. The BMS protects the battery from deep cycling, so Tesla can go a little bit beyond 500 equivalent cycles.

BUT - did you read the "CHARGE / DISCHARGE REST TIME: 20min" in the life diagram (to the right)? In automotive use, these 20 minutes cannot be guaranteed at all! Imagine stop-and-go traffic with quick alteration of acceleration and regen. Or plugging in right after you arrive at a charge point. The BMS can do very little here to protect the battery and still satisfy user experience. Then there is the point of 4C discharges when flooring the goose pedal - though Roadster owners report no impact on the pack so we are lucky here :biggrin:

 

[gg_got_a_tesla]

My situation is very similar to Rifleman's:

- 55 mile daily commute (much less than his 80 miles)
- 40 miles at 60-80 mph (with occasional jackrabbit driving) and 15 miles at 25-40 mph
- no charger at work and our Facilities guys have firmly said no to multiple Leaf owners :frown:
- car in enclosed garage at home at night
- car would be in a parking structure at work though (not completely exposed to the elements) and it doesn't get too cold in NorCal
- will have 2 average adults and 1 child carpooling back and forth on weekdays
- will need to do fairly periodic 100-120 mile weekend trips

I can't see "sponsoring" a charger at work as changing employers is always on the cards.

I wouldn't want to change my driving habits (the 60-80 mph + jackrabbit part! :biggrin significantly; after all, that was the whole point of a Tesla over a Leaf, right?! Electric and fun at the same time.

Nor would I want to make compromises with AC consumption etc. Do I need an electric drive so bad that I give up on basic creature comforts that I'd take for granted in a gasser?!

Given all this (and the possible degradation over the years, worst case or otherwise), I had long resigned myself to going for the 60 kWh battery pack even though I may not really "need" it initially. $10K for some peace of mind really. This was even before the recent stepchild treatment given to the 40 kWh pack by Tesla...