Tesla cars allowing batteries to become fully discharged?

[Sub_Umbra]

Ten years to start meaningful production even in the face of demand and limited supply?

Yup. It turns out that Rare Earth Minerals is a very poor term for minerals that are scattered very thinly throughout the entire world. Searching will turn up a big effort in (I think) Kansas. They are dumping boucoup bucks into this and according to the news reports it will be at least ten years before any significant production is reached.

By all means, look it up and correct me if I've got it wrong.

 

[Wrend]

...

Please don't mistake my post for a conversational "debate." I'm just offering my point of view, not trying to change your beliefs.

 

[Sub_Umbra]

No worries there.

 

[hellokitty[hk]]

AFAIK, the 18650s are A123 LiFe chemistry.

 

[StarHalo]

It's a toy; people who spend this much on toys have no problem with the ridiculous maintenance budget. And it's essentially half the price of the cheapest Ferrari.

The version I can afford is in Forza 4 for XBox. It's a unique challenge to hustle around the track, since there's no gear to select for each specific turn (and no way to downshift if you blow it), and no engine sound to tell you what the motor is doing..

 

[jasonck08]

Not only did Tesla forget to install a Low voltage cutoff, they also made a mistake in choosing to use cells rated for ~300 cycles.

The car gets 200 miles max per charge and the cells in the pack are good for 300 cycles tops. So that means that if you exclude the fact that the battery discharges significantly on its own, and you do the math 200x300, that means the car is good for 60K miles max before needing a new battery @ $40K+.

So assuming there is no additional maintenance besides tires and brakes in the first 60K miles, you are still paying likely around ~45K in maintenance for driving 60K miles. Not only that but the fact that it discharges ~25Kwhrs per week. 25Kwhrs is going to cost around the price of a gallon of gas. And thats the price for just storing the vehicle! The only green I see in the tesla is the stack of money you hand over to buy and maintain one of these cars.

 

[Wrend]

Which cells did they use that only get 300 cycles?

AFAIK, the 18650s are A123 LiFe chemistry.

If this is the case, then more fully discharging, and cycle life shouldn't be much of an issue.

 

[jayflash]

Electricity was once feared and banned in some places. Getting to the moon was considered folly. It remains possible that affordable, reliable, electrical storage may become available in acceptable size/weight limits. I won't be holding my breath, but, who knows? Plug the car in during off-peak periods and existing AC sources may be sufficient.

Too bad electric cars aren't yet practical because motors are superior to ICE's and the torque at stall would make them a blast to drive.

 

[AnAppleSnail]

Too bad electric cars aren't yet practical because motors are superior to ICE's and the torque at stall would make them a blast to drive.

It depends on how your motor is built - but of course if you do it right there is potential for great fun. I wouldn't mind a diesel/electric (Well-tuned diesel generator powering motors and/or battery storage) powered car with high-torque hub motors. Trains and tugboats use these for 100% torque at zero rpm to begin moving. With a generator and some buffer power source, it would be delicious to smoothly press the accelerator to the floor and silently (or not) reach speed.

 

[StarHalo]

the torque at stall would make them a blast to drive.

The Tesla modulates the amount of power you get from a stop as a sort of launch control; you don't get 100% of the motor until roughly 45 mph. Flooring it from a stop, the tires barely chirp, and you can watch the power gauge climb as more power is delivered at more speed, giving you a nicely controlled launch. You can somewhat circumvent it by brake torqueing (depress brake and accelerator, release brake), or drifting/donuting so the motor is already pegged going into a low speed, but if you really want the wall-of-smoke burnout, do it in reverse - the short gearing combined with unmodulated, almost instantaneous 100% power leaves the wheels spinning until ~50 mph..

 

[shadowjk]

Amusingly in colder climates the grid would be able to handle it better, as people already plug in their internal combustion engine powered cars to the grid before leaving to or from work, in order to preheat the engine to reduce wear&tear, and cheat the windows to reduce the ice thickness on them, but on the other hand the amount of power you'd need for onboard heating would drop range somewhat

 

[jasonck08]

Which cells did they use that only get 300 cycles?



If this is the case, then more fully discharging, and cycle life shouldn't be much of an issue.

Panasonic NCR18650A.

 

[Wrend]

Yes, the spec sheet on those cells doesn't look all that good. Could probably get better cumulative lifetime capacity (and of course cycle life) if the cells aren't as fully discharged.

http://www.panasonic.com/industrial/includes/pdf/NCR18650A 3.1Ah data sheet.rev1.pdf

 

[StarHalo]

Amusingly in colder climates the grid would be able to handle it better

I'd definitely prefer the Leaf for cold weather duty; the Tesla's rather tail-happy rear wheel drive setup is very Corvette-like, precisely not what you'd want for inclement weather. The pedestrian Nissan with its skinny tire front wheel drive is vastly preferable for snow and ice.

 

[psychbeat]

a guy in a Tesla pulled up next to me and we admired each others cars today.
Im driving a beat 1986 Corolla GTS with a drift set up
Ive got only 1 Panasonic NCR18650a in my car tho...
in my glovebox light :naughty:

I think Tesla is a cool company even if there are some problems with the cars
we still benefit from the attempt to see whats possible no matter if it fails to
save the polar bears or make $$$ :thumbsup:

 

[itguy07]

Did you know that you could charge a battery powered electric car with a relatively cheap gas powered generator and still get better gas mileage and pollute less?

Outdoor Power Equipment makes a LOT of pollution. We're talking an hour of mowing is something like driving your car 300 miles. And not to mention you'd upset your neighbors running an open frame 5.5KW+ generator every night to recharge your electric car.

We've got a cheap 5.5kw Harbor Freight unit for power outages. It's a great generator. Will blow through 5 gallons of gas in 8 hours running at 1/2 - 3/4 capacity. We got to test that out during the Halloween snowstorm in the Northeast. So I drive my car 100 miles on 5 gallons of gas. That's, what 20 MPG? I get better than that in mixed city/highway driving in my 360hp car. On straight highway I can get up near 25MPG. And that's an AWD car that weighs about 4000 lbs.

Oh, and Natural gas generators are about the same as the fuel contains less energy than gasoline.

A Diesel generator would be the way to go but you have to feed it somehow and it still doesn't get around the fuel and sound needs/issues.

Electric cars would be great if the infrastructure was there but it's not.

 

[cue003]

Not only did Tesla forget to install a Low voltage cutoff, they also made a mistake in choosing to use cells rated for ~300 cycles.

The car gets 200 miles max per charge and the cells in the pack are good for 300 cycles tops. So that means that if you exclude the fact that the battery discharges significantly on its own, and you do the math 200x300, that means the car is good for 60K miles max before needing a new battery @ $40K+.

So assuming there is no additional maintenance besides tires and brakes in the first 60K miles, you are still paying likely around ~45K in maintenance for driving 60K miles. Not only that but the fact that it discharges ~25Kwhrs per week. 25Kwhrs is going to cost around the price of a gallon of gas. And thats the price for just storing the vehicle! The only green I see in the tesla is the stack of money you hand over to buy and maintain one of these cars.

Interesting. Same thoughts I have been having with this vehicle. I have been looking into the Model X that was just announced and my concern are the costs after purchase.

 

[Wrend]

...

The fuel gas generator would need to be optimized for the task, but what I said is definitely doable. Maybe not with your setup as is, of course.

 

[jtr1962]

Putting aside protection circuitry, using 6831(?!) 18650s instead of maybe about 120 of these is just a brain-dead decision. Same amount of energy, less than 1/50 the number of cells to assemble into a pack, 2000 cycles instead of only 300, safer chemistry, costs about the same. OK, the pack would be a few hundred pounds heavier, but with regen braking weight doesn't significantly impact range. Their engineer must have been asleep at the wheel.

And the grid is plenty ready for EVs now. We're not going from zero to 100 million EVs overnight. We could beef up the grid where and when needed as we go along. I suspect also that solar power will become mainstream in the same time frame as EVs, and lots of people will be charging their EVs off solar power, making the whole grid issue moot. An interesting factoid is that petroleum refining is the single biggest user of electricity in the US. As you go to EVs, more and more of that power will be freed up for charging.

 

[LEDninja]

I learned a new word today.

In the last 2 years I BRICKED some of my lithium-ion flashlights.
When recharging my Li-ion cells I always check the voltages first. The thing that surprises me is the voltage of the cells gone bad are at 0.0V to 0.08V. I expected to see some at ~2V or so. Nope.
The last one the protection circuit tripped and I was unable to untrip it. Won't charge, won't discharge, voltage measures above 3.6V.
I have tossed over half a dozen cells so far. (18650, P18650, 14500, P14500, 10440) No big deal - mostly DX types. Luckily I do not have to spend $40,000 to replace them.