Running costs / longevity

T@oo · Mar 30, 2010

From ICE cars, a BEV will have much reduced running costs. Basicly it's tires and washer fluid. Brake pads and disc will last much longer thanks to regen braking. The AC motor is made to last forever. The battery is the biggest factor. The 100k miles figure for down to 80% capacity makes it a five years thing for me. But considering the degration curve will flatten (is it?) would it be save to assume that at 200k miles will be at, lets say, 70%? What do you think?

What about fluid pumps / hoses? Fans? How long is the PEM supposed to last? Are there any reports on dying PEMs?

TEG · Mar 30, 2010

I think things tend to get progressively worse... Pack replacement starts to become desirable due to not only loss of capacity but reduced performance due to increased internal resistance.

GNOME Power Manager Manual

Figure 13. This graph shows the capacity of a typical lithium ion battery over a few hundred charge-discharge cycles.

Range mode charging (to higher voltage) hurts pack life:

Note, the above charts are general representations, NOT specifically meant to indicate what will happen with a Roadster pack.

T@oo · Mar 30, 2010

Ah well, that's bad new for me I'd guess. So I definitely need to put the replacement costs of the battery in my calc.

Let's hope that the battery for the Model S has some improvements regarding discharge cycles.

Todd Burch · Mar 30, 2010

Not to mention that, due to the increasing internal resistance, it's going to be less and less efficient to charge as the battery degrades.

I see it like this: Even 70% of a 250 mile battery would get you on the order of 150 miles (roughly). That's still plenty for most of my driving, and the longer I can put off getting a new battery pack, the better the next battery pack will be. Who knows...maybe your second Model S battery pack will have 1000 miles range!

Cobos · Mar 30, 2010

My idea has been to continue the car payments after the loan is payed back and use that to build up a nice little battery-replacement-fund. That should be enough for a new battery.

Cobos

dpeilow · Mar 30, 2010

Question: What's the MTBF of the Tesla motor in typical stop-start operation?

TEG · Mar 30, 2010

AC motors are usually one of the more reliable parts of a system like this.

Random examples:
AC Drive features MTBF of 28 years., Yaskawa Electric America, Inc.

AC Drive features MTBF of 28 years.

AC Motor Drives Data Sheets from Eaton's Cutler-Hammer Drives

Robust design - 500,000 hours MTBF

Aside from usual consumables (tires, brake pads, etc.) my concerns would be:

#1: Batteries wearing out from cycling.
#2: Batteries wearing out from old age.
#3: Batteries wearing out from improper charging (e.g.: Left off charge too long, left at full charge in extreme heat, etc.)
#4: Auxiliary DC motor components wearing out - water pumps, cooling fans, etc.
#5: Some component in the PEM wearing out (e.g.: capacitors). Possibly due to environmental conditions like moisture or static discharge. <-- (Since inception, I bet this is where they have made more advancement than anywhere else. )

vfx · Mar 30, 2010

TEG said:
#1: Batteries wearing out from cycling.
#2: Batteries wearing out from old age.
#3: Batteries wearing out from improper charging (e.g.: Left off charge too long, left at full charge in extreme heat, etc.)

All reasons that I would be terrified to buy a Leased or Rental Electric car. Am I right? Can you even test for this at purchase?

T@oo · Mar 30, 2010

All reasons that I would be terrified to buy a Leased or Rental Electric car. Am I right? Can you even test for this at purchase?

My understanding is, that at least for the battery Tesla records any events. They'd need those for warranty issues anyway. So you should be able to phone up Tesla with the VIN and they'll be able to tell you.

dpeilow · Mar 30, 2010

TEG said:
AC motors are usually one of the more reliable parts of a system like this.

Random examples:
AC Drive features MTBF of 28 years., Yaskawa Electric America, Inc.

AC Motor Drives Data Sheets from Eaton's Cutler-Hammer Drives

Aren't those both power electronics for driving the motors, rather than the motors themselves? Or am I missing something?

T@oo · Mar 31, 2010

OTOH I found this

If we take the standard fairly abusive battery charge cycles the battery manufacturers carry out, that implies driving say 200 miles in one stretch before recharging each time and that works out at 100,000 miles of life. And that’s with that rather unrealistic implied usage pattern. In reality, the battery should be good for more than 100,000 miles.

here.

But it also mentions five years calender live. So even if I would put it in "holiday" mode for five years it'll be worn out?

TEG · Mar 31, 2010

T@oo said:
But it also mentions five years calender live. So even if I would put it in "holiday" mode for five years it'll be worn out?

Yes, batteries tend to have a "shelf life" and will degrade over time even if you aren't cycling them. Some cell formulations last longer than others. I can't really say how a Roadster would behave if you just put a new one in a museum for 10 years, but I suspect it would be not as good as new.

vfx · Mar 31, 2010

T@oo said:
My understanding is, that at least for the battery Tesla records any events. They'd need those for warranty issues anyway. So you should be able to phone up Tesla with the VIN and they'll be able to tell you.

AHH but will they? Privacy issues ya know...

stopcrazypp · Mar 31, 2010

T@oo said:
OTOH I found this
here.
But it also mentions five years calender live. So even if I would put it in "holiday" mode for five years it'll be worn out?

I should probably mention that the calendar life will depend on what charge level and temperature you are storing the battery pack at. The "storage" mode on the Roadster optimizes this.

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Running costs / longevity

T@oo

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TEG

Teslafanatic

T@oo

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Todd Burch

14-Year Member

Cobos

Model S owner since 2013

dpeilow

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TEG

Teslafanatic

vfx

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T@oo

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dpeilow

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T@oo

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TEG

Teslafanatic

vfx

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stopcrazypp

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