40 kWh dilemma

[Rifleman]

I have always planned on getting the 40 kWh. My daily drive is 65 miles round trip, with one day a week being about 90 miles. A car with 160 miles range seemed perfect for me (especially as I will still have a second car)

Now that some new estimates of range and battery degradation are starting to become available, I am starting to have doubts about the long term viability of the 40 kWh pack. This is how I figure it :

the 85 KW Model S gets 265 EPA range. 85/40 = 2.125 and 265/2.125 = 124.7 miles. So lets guesstimate that the EPA range will be 125 miles for the 40 kWh battery. I am assuming that the EPA estimate is in range mode, so lets take 125 *.8 to estimate the normal mode range. This give us a solid 100 miles of normal mode, real world range (not bad compared to the competition)

This would be just fine for me, leaving 10 miles extra on the longest drive of the week (plus an extra 12 miles in reserve if I change the car to range mode). The problem begins when the pack starts to degrade. I drive about 15,000 miles a year, so after 3-4 years, my battery pack will not have the capacity that it did when it was new. Let's say it looses 25% capacity. Now I only have 75 miles real world range, and I am being forced to drive my trail blazer one day a week, and have to think about how far away lunch is if I choose to go out for lunch one any of the other days.

The way I look at it, I have 2 real options :

1. Pay the 10K extra and get the 60 kWh battery. This may mean adding an extra year to the loan, or deferring when my number comes up so that I have more time to save up to pay the difference as part of the deposit.
2. Buy the 40 kWh battery, and just start saving, knowing that in 3-4 I have going to need to buy a new battery. Doing this is betting on a replacement 1, being available, and 2, costing $10,000 or less.

What does the hive mind think, is my drive to long for the 40, or should I stay the course, and hope for the best down the road?

[bonnie1194]

I'd put some effort into ensuring a charge point at your destination, effectively cutting your need for range in half.

[Teslawisher]

Something else to consider... charge points at the workplace.

If there is one - would that factor into your decision or alleviate some anxiety here?

If there isn't one - maybe you have time to discuss with your employer and get one installed before your car is delivered. Anyone else at your company have have plug-in EV or hybrid vehicles? Group with them to form a larger negotiating group.

I'm in the same boat. 100 miles real world driving would be fine for me too, but I would have less anxiety about range degradation as you as my typical round trip is about 40 miles.

[Teslawisher]

lol Great minds??

[vfx]

a 2% a year range loss. What about buying a new longer range battery with that $10,000 in 10 years?

[epley]

Also depends upon the driving conditions. If it's mostly freeway vs. in-town, as this will affect the range as well. Since the Tesla can charge anywhere, you can recharge a bit while at work so you don't have to worry about driving somewhere for lunch, etc. Having a 240/40 level charger would be even better. If the finances are doable, you won't regret the longer range of a bigger battery, but I don't think you have anything to worry about!

[ElSupreme]

My driving (right now) is pretty much the same as yours. Four days I travel about 60 miles, the final day I travel ~75-80 miles.

I am not using the 85kWh / 40kWh ratio when calculating my numbers. Rather I am using the 300miles / 160miles published numbers Tesla provided. I am not sure this is good or not. Anyway the ratios are different and you get slightly better numbers if you consider the ranges Tesla has published.This would give you about 142 miles per range charge and 114 miles for a standard charge. I am using 96 miles as my alert range in my spreadsheet. This accounts for some 80mph highway speeds.

I am dealing with degradation with two assumptions. The first is I can always drive a bit slower on the days where I need to travel further. Second as I become more familiar with the car, I will become more comfortable running it to the very end of the battery. Third in the future I will gain charging opportunities. And finally I am also accepting that I will need to purchase another battery; hopefully this is after 150,000 miles / 8 years, but I am planning on 100,000 miles and 5 years (conveniently after my loan is paid off). I am also alerting in my spreadsheet if I come within 16 miles of my standard mode charge range.

Also are you sure your driving habits will be the same in 5 years. Will you have the same job? Will you live at the same house? Will your current office move? A lot can change in 5 years.

EDIT: And as much as Tesla won't like it I have no problem charging in range mode once or twice a week. It helps that I am already planning on buying a new battery.

[Teslawisher]

If the finances are doable, you won't regret the longer range of a bigger battery, but I don't think you have anything to worry about!

You're definitely right here. If you get the bigger battery, you WILL use it, so it won't be for naught.

[Rifleman]

I actually already have the ok to install a 14-50 outlet at the fire station where I volunteer (and spend one night a week). Getting my actual job to install a charger is proving to be a much more difficult proposition, and I am not optimistic about getting a charger installed in the next decade or so.

[AndyM]

Rifelman -
You're right to do the math up front. Yet, you will have plenty of time to wait to hear from Model S actual owners with in-field experience before you have to make the decision.
I view the EPA 5-cycle numbers as closer to worst-case... they are a calculation of driving behaviors anywhere between "hypermiler" and "leadfoot". Tesla's own range estimates have been exceeded on the Roadster, and I expect that trend to continue. So I would use Tesla's range estimates as conservative.
2% decrease in range per year to accommodate battery degradation seems right to me.
As for charging at the workplace: I am designing my charge habits so that the car charges when and where I sleep. Road trips can be an exception to that rule. But not my office.

See if you can afford the bigger battery, to be flexible if you get laid off, or if other plans change in your life. Be prepared. Replacing it when you need it later will be more expensive than selecting one you might need today. I might be too risk-averse; I am not going to bet on prices that might go down in battery tech - yet.