What questions should I ask Tesla Motors?

<div class='quotetop'>QUOTE(daniel @ Mar 5 2007, 10:42 PM) [snapback]400670[/snapback]</div>

I'd pin them down on the batteries a bit more. If wikipedia has the specs right, this vehicle is 1000 lbs of li-ion batteries with a car wrapped around it -- 40% of the mass of the vehicle is the battery.

Based on the RAV4 EV and on the proposed Prius PHEV conversions, I'd guess the battery pack for this car is going to cost on the order of $20K to $25K. So that's an expensive half-ton disposable, and I'd get more information on that.

First, what's the guarantee on the batteries? Do they guarantee 5 years of life, for each cell so to speak, or is that just average life expectancy, and the guarantee (if any) is something else? If the batteries lose capacity as they age, under what specific conditions would they replace all or part of the battery pack for free or for a reduced price? In other words, what, exactly, to they guarantee about the battery pack?

The other factor I came across while researching a PHEV Prius is that current production li-ion batteries simply age, no matter what, so that at some point you are limited by the lesser of number of charge cycles or calendar age. So it's no like you can make the batteries last just by taking the car out on weekends.

Ask them which it is that sets their 5 year expected life -- does that reflect number of charge cycles or calendar aging of the li-ion batteries. If it's the calendar, then there's nothing you can do except keep the batteries cooler. And realistically that probably won't help much. If it's charge cycles, then if you use it more gently, it'll last longer. (There's also a question of how they got that 5 year number, given that the batteries probably haven't been in production 5 years -- it's probably an extrapolation from an accelerated aging test.)

The tesla site says 100,000 miles of peak performance, followed by gradual decline. To me, that suggests that calendar time is the limiting factor. I saw that in another battery I was researching -- the charge cycles data looked great -- looked like the life of the vehicle -- until somebody pointed out the calendar time aging issue. So, if you want to use up the battery, drive it a lot -- if I have guessed right, that's the takeaway. If you leave it in the garage and drive it on weekends, the battery will still be dead in 5 years -- if I have guessed right that calendar aging is the limiting factor in their five-year estimate.

And, I've read conflicting advice on the "charge cycles" portion of that. Some people say that constant shallow charging of li-ion batteries shortens usable lifetime output relative to deep discharge - charge cycles (within the safety limits of the battery). That is, it extends battery life literally to keep the number of charge cycles (regardless of depth) to a minimum. So don't charge until the battery is nearly dead. Others say no, the limitation on charge cycles is in effect a limit on the total lifetime current that passes throught he battery -- so charge whenever you want it makes no difference. Maybe all of that is bunk.

The Tesla site says charge whenever you want to. Actually, that portion of the site has a lot of biased and misleading information on it. Says that electric vehicles were limited to 60 miles before the Tesla, that batteries had memory problems, and so on. All of which was true, for some cars and some batteries. But the range of the Tesla is a reasonable gain over the best prior production cars available, not quite the quantum leap the website would suggest.

Finally, everything I read suggests that five years from now, you ought to be able to buy a much better, longer lived battery pack than you'll get today. So, with any luck, this would be a one-time hassle over the life of the vehicle.

I assume they've fully addressed the fire hazard issue, but I'd still ask them what would happen in a bad rear-end crash if the battery casing is breached by a piece of sheet metal? Presumably they wouldn't be allow the market this unless they'd solved it, but I'd definitely get a written explanation of why their batteries are safe from spontaneous combustion even under extreme circumstances.

 

Wow! Thats great that you are ordering a roadster! please tell us how it drives when you get it (i'm sure it will be a blast!)

In regards to the battery, lithium ion batteries usualy have a callender life of around 5 years before their molecular structure degrades and they begin to gradualy loose their energy and power density. However, i believe that this will not be a major issue. This is because of the extremily fast evolution of the battery technology. I mean, just think. 5 years ago we had EVs that used nimh and went 100-120 miles per charge. Now, we have a car that uses li-ion and goes 250 miles per charge! imagine the capibilities of a lithium based battery 5 years from now!

Also, i believe that Tesla actualy pays you to recycle the battery.

On another note, YAY MY FIRST POST! XD ! I'm a long time lurker and am happy to be a part of the priuschat communty!

 

<div class='quotetop'>QUOTE(daniel @ Mar 10 2007, 12:00 PM) [snapback]403457[/snapback]</div>

Thats a good idea. i myself am trying to influence the reslt of my family to consider getting a WhiteStar when they come out ( i cant buy it all by myself ). My main motive is the projected 4 dollars a gallon that is Supposed to happen this summer . And... Oh! Thanks for the welcome .

 

Yes welcome Clay (and howdy again!)

Buy the EV to save the planet (Tom Hank's words) but look brilliant to others when you don't have to buy the $4 gas.

Every time I hear people saying they want an EV *because* of expensive gas, it just makes me want gas to be more expensive sooner. And that doesn't win me many friends. But if that's what it takes, let's remove the oil subsidies and see how attractive EVs really are.

 

<div class='quotetop'>QUOTE(darelldd @ Mar 13 2007, 02:38 AM) [snapback]404694[/snapback]</div>

Yeah I was just saying that to ALL my friends too and they were like this <_<

I can't help it cause I know it's going to get people thinking about other types of vehicles. I hope the crap shots up to $5 gallon.

I'm hoping the rising of the gas prices at least helps me sell my Pruis!!

 

Most adults don't understand why I seek out the most expensive gas stations when I fill up the gas car. My six-year-old has it all figured out though. "You do it because you want people to stop using so much gas, right?" Was what she asked just yesterday, actually.

 

<div class='quotetop'>QUOTE(daniel @ Mar 14 2007, 08:29 AM) [snapback]405407[/snapback]</div>

You and I are certainly NOT in the majority here! You can see Prius interest (as well has SUV interest) come and go with gas price fluctuations. US drivers are a fickle bunch! Honestly - my neighbors thought I was some wacko when I got my first EV. Just a curiousity. When gas hit $3, I was suddenly the smartest guy in town. Go figure.

Again... not caring about the price of gas puts you in the minority here! Just look at the rash of posts on PC every time the price changes by 10c. I know very few folks who don't seek out the cheapest gasoline (unless they also have a brand affinity).

I have confidence that I can explaing this since I have practice with my daughter:

We first have to stipulate that people will burn more gas if it is cheap, and will burn less gas if it is expensive. In general, I think this is a safe bet. And then...

If every customer tries to buy the lowest cost product (gas or whatever), everybody who sells that product must find ways of keeping the price as lower or lower then the competition. If a block has four gas stations on it, the cheapest station is likely to get more business than the more expensive ones. If the expensive stations don't get enough customers, they must lower their price.

My job is to frequent the expensive stations to keep the price high, wich allows the lower-price stations to go a bit higher while still being lower, blah, blah.

Sure it is insignificant - but I try to do my part.

 

<div class='quotetop'>QUOTE(daniel @ Mar 15 2007, 04:22 AM) [snapback]405973[/snapback]</div>

Oh, I fully agree that my efforts are insignificant - much like us driving an EV for which I generate power on my roof. One guy can't change anything. But just imagine if LOTS of people started to realize it was possible? Yikes.

Expensive gas seem to be the ONLY reason compelling enough for the general driving public to consider something other than a GIANT, overpowered petrol vehicle. If this weren't the case, I'd be all for cheap gas prices! Regardless, I don't think we should be keeping prices artificially low just to make it appear that this form of energy is cheap.