It seems like it's an inherent in this sort of battery. I'm not sure what Tesla could do to offset this. Computer makers mostly don't offer warranties in the case of negligence or intentional damage. The same seems to apply here.
Rather than brick the battery, if it is parked and below a certain level, release a normally open relay that completely disconnects the BMS from the cells. Recovering from this state would require special charging and recalibrating of the BMS (possibly done at a shop) but it would be better than bricking the pack.
Rather than brick the battery, if it is parked and below a certain level, release a normally open relay that completely disconnects the BMS from the cells. Recovering from this state would require special charging and recalibrating of the BMS (possibly done at a shop) but it would be better than bricking the pack.
Disconnecting the BMS does not eliminate self-discharge, only the parasitic load. Draining your batteries to the point of being functionally dead, and then leaving them in that state for an extended period, will still "brick" them just as badly.
Switch does not solve the problem, "backup battery"? You're just delaying the inevitable, why not just demand that they make the batteries bigger in the first place?
What good does a "mini engine" do? You can't turn it on automatically, that's an enormous safety risk and would never make it past insurers or the government, and it can only last as long as its fuel holds out, again you're just delaying the inevitable. Solar panels don't help if you're parked in a garage, which is where most people park their fancy roadsters, and they'd have to be huge to maintain the charge anyway.
And absolutely none of this contradicts my original point: It's a technological limitation. This is how batteries work. You're not proposing a solution, you're proposing unworkable band-aids.
It's a bug in the same sense that internal combustion engines will begin to have problems if their motor oil is not changed. It's inherent to this kind of battery.
It's inherent to any lithium ion battery design which is why every laptop, iphone, etc that uses a lithium ion battery has circuitry that cuts power when the batter reaches 1% to 5% it can occur in your laptop if you discharge the battery entirely and then leave your battery uncharged for months (or less if stored cold).
Some kind of chemical change occurs in Li batteries when completely discharged.
Good answer. In case anyone wants more detail, wikipedia is a little vague, but has the basic idea right:
"Overdischarge supersaturates lithium cobalt oxide, leading to the production of lithium oxide...deep discharge may short-circuit the cell, in which case recharging would be unsafe."
and
"Overcharge up to 5.2 Volts leads to the synthesis of cobalt(IV) oxide...if overheated or overcharged, Li-ion batteries may suffer thermal runaway and cell rupture. In extreme cases this can lead to combustion."
The possibilitiy of thermal runaway or fire from overcharging is actually fairly likely with Li+ ions, since they will react with any non-inert substance.
The short circuit caused by undercharging can affect other cells in the pack, leading to overheating and combustion.
maximum lifetime is obtained when you store them at around 66% charge at 4C, which is the temperature of your fridge, take them out ever few months and charge them, you can get less than 1% capacity degradation a year.
Every laptop that uses a lithium ion battery should have this problem. Oddly enough every laptop manufacture has included circuitry that cuts battery power when it reaches 5% (when the OS reports 0% it's actually ~1-5%). Tesla should have no problem fixing this, the onboard electronics will die anyway when the battery dies so why not have them die a few hours earlier and allow 'recovery' by charging the vehicle.
Yes. If you completely discharge your laptop and then stick it in a closet for a couple of months without charging it, the battery will likely be completely unrecoverable. The exact amount of time it takes will depend on the battery of course (and the ambient temperature).
Yes, and I've done that. Took longer than a couple of weeks though. Brand new battery in a MacBook that discharged then went in storage for a while (a half-year I think). The next time I opened it the battery was completely dead and wouldn't hold a charge.
I left my MacBook on but the lid closed and went on a weeks holiday (not sure how much charge the battery had) when I come back it was dead and now will not take a charge.
As its £90 for a new one, I just leave it plugged into the wall now.
Yes, I've bricked my old Macbook by doing that (for several months).
I bought a new laptop, so closed down my old Macbook, and stuck it away.
A few months later, I found I wanted to grab file from the old macbook, and noticed it wouldn't run from battery. It'll work fine plugged in, but the battery is registered as full discharged, and the Apple page says "Buy a new battery".
Which is what the Nissan Leaf does(pretty nifty idea, I'd say). But its not really a solution in the sense that it wouldn't work for cars parked inside.
Could this really not be prevented by a $10 microcontroller and a big-ass relay to just disconnect the battery if it reaches a certain discharge state?
Even my iPhone can turn turtle to protect its battery when it gets too low.
Also how much power does it take to keep the damn thing plugged in? The article indicates that a 100 foot extension cord isn't enough just to break even and the car discharges even when plugged in. A 100 foot cord of cheap 16 gauge wire can still supply almost 900 watts before the voltage drops below 100v. So it uses a kilowatt just to stand-by without even charging? That's one hell of a power vampire.
I think maybe they should spend a bit more time on the fundamentals and a bit less time on fancy bird-wing doors if they want to have a real product. The real car of the future is just a big dumb tray full of indestructible nickle-iron batteries and 4 wheel-hub motors bolted to the corners.
The account of the Tesla discharging while plugged in to a 100-foot extension cord strikes me as suspect. It's anecdotal at best. Have a look at the Tesla Roadster "Charging" page:
Using 120V @ 15A, you get a charge rate of +5 miles (of range) per hour. Obviously not the optimal solution, but not a net negative either. Adding a 100 foot extension cord isn't going to diminish the available current enough to result in a net negative, so either the owner had additional electrical issues, or simply failed to plug it in and is making up excuses.
Totally Agree. There are no names, only anecdotes and the science is suspect. This article is 100% B.S. and I wouldn't be surprised if it was planted by a competitor.
The bigger an industry is, the harder they fight for their existence. Elon Musk is not just taking on the second biggest industry, the auto industry. He's also taking on the biggest industry: oil.
It looks like they switched from ignore/mock to attack. He's getting somewhere.
First they ignore you, then they laugh at you, then they fight you, then you win. --Gandhi
120v @ 15A is 1800 watts. As I said, I was able to measure the wattage being delivered at the end of my 100 foot 16 gauge "home depot" orange extension cord connected to a space heater and found less than 900 watts being delivered to a load that normally pulls 1750. The voltage had also dropped below 100 volts.
Its possible that the Tesla simply won't charge at all if the current or voltage on the line becomes too low. In this case, it would be "plugged in" but not charging.
Edit: Lets figure it out: Range=244mi. Battery capacity=58kWh. So: 5 miles takes 1.086kWh. 10% is lost in chemical conversion so we really need 1.207kWh for those miles. We pull at a rate of 1.8kWh/h from the plug. So 600 watts or so is lost elsewhere. We know the "always on" battery cooling system alone takes around 150 watts. Its not that far fetched.
Edit: I deleted my comment below where I calculated the cost of keeping the car on standby because I don't think I made clear enough (and didn't want to type it all twice) the difference between the actual discharge rate of the battery and the amount of power required at the charger to stop it. It just seems to take a lot of power at the charge port before any gets to the battery. The battery seems to discharge at an average rate of just 30 watts, but it seems to take a much, much greater amount of power input to prevent this and failing to provide this power has dire consequences. Why?
The pack is 53kWh according to wikipedia and discharges in 11 weeks from full according to the article. Unless I botched a decimal place, that is a 29 watt idle load. (53000 watt hours / (11 weeks * 7 days/week * 24 hours/day) ). In perspective, that is about the same as 4 night lights.
Clearly there is about 20 times that much power available at the end of a 100 foot extension cord in a standard household outlet.
Failure modes available:
• Was not actually plugged in.
• Was unplugged then plugged back in much later, possibly unbeknownst to owner. (Someone in my household unplugs my DVR to use an outlet. Grr.)
• Was on a switched outlet. (I once bought a new drill over that. Who knew one of the duplex outlets was switched and the other not? But the new drill wasn't $40k.)
• The Tesla charger could have a cutoff where it stops charging if unable to pull X amps where X is somewhere between 7 and 15. This could be either intentional or unintentional. Brown out protection circuitry, if needed by the design, could do this. They also might fear they are setting your house on fire by dropping 800+ watts somewhere in a wall and shut off.
A roadster that is plugged in, is not really "off". It will provide power for heating or cooling of the battery pack if the temps get too high or too cold. This would be much more than a small idle load.
That's because a 16 gauge extension cord isn't supposed to supply 120v @ 15A. A 16 gauge cord is only good for around 10 amps.
Which means you have a point. If the owner in question plugged the Tesla supplied 120v cord in to an additional 100-foot, 16 gauge cord, they might have a net loss situation on their hands.
Er, no, this is probably wrong. The voltage drop is due to resistive losses in the long (and skinny) cable, and the resistive losses depend on current flowing. So, unless there are some weird effects due to the car's electronics, you cannot stop the charging, only slow it down.
So the charger sees the 120 V, decides to begin charging, current flows, and the voltage drops. If the voltage drops out of range, the charger aborts because it's out of design spec and/or there's a significant amount of power being dissipated, probably by resistive heating (i.e., risk of fire).
A little OT, but I've found that it's better to make your own extension cables. I have a 1kW tank heater that is about 100' from the closest outlet. The cost of 100' of 12gauge house wiring and a plug, socket and outdoor outlet was much less than even a cheap 100' extension cord and has much less voltage drop.
That depends on your application. Extension cords are more expensive because they are made of stranded wire that remains flexible and resists breaking. Household wire is solid and not meant to be rolled and unrolled repeatedly. It will get kinks and weak spots. But if your application is for a relatively static run, left in place for a long time, the household wire is better.
The charge circuitry probably turns on at a high charge rate, senses the line voltage drop below 100v, and shuts down for a few seconds. Stuck in this loop, it might never deliver much charge.
Could this really not be prevented by a $10 microcontroller and a big-ass relay to just disconnect the battery if it reaches a certain discharge state?
Not necessarily. This might help, but the battery will also have self-discharge, meaning that it can lose charge without being connected to any load at all. If you get the charge down low enough, and then wait long enough, then even a full disconnect from the system won't help.
You could add a $100 mobile phone, which auto-calls a service center. If 1% of cars get "bricked", that's $10,000 per car saved, not including intervention costs. Even with some false positives, it would be worth it. Of course, that cost is carried by Tesla, not the customer.
"The Tesla manager called me to warn that my car was in trouble" is a much better customer experience than "my Tesla broke down, and cost $40k to fix".
Cars used to have the same problems with oil changes. This got better, as customers were educated (at the cost of a lot of cooked engines), and cars were able to warn their owners, and run for longer without oil.
That's exactly what Tesla do, even once having gone so far as tracking the car down via GPS and charging it themselves when the owner was unresponsive.
As a Model S reservation holder, it pegs my pocketbook meter. If I'm about to lose $40K on my car because of a battery, I have no problem with them showing up in my driveway to charge the vehicle if necessary.
Creepy? I'm more worried about the app-of-the-day sucking down my iPhone contacts. THAT I find to be more personal than my vehicle location.
IMO they're both creepy, and using one to justify the other isn't helpful. Apple has already come out and admitted that was a mistake and they will be rectifying it, so it doesn't really help your case much.
In both cases though it's not the action so much as it is the fact that you weren't able to opt out of it, or in many cases you aren't even aware of the possibility of it happening.
It's the same violation, and in both cases it's equally creepy. Apple got called out and did something about it. What will Tesla do?
Small portable gadgets using LiPoly batteries (which I assume the Tesla is using) can be left for months or years without charging, and then nursed back to life. If sufficient charge is left in them, and the circuitry is smart enough to recognise that the battery's about to die, the time before complete discharge could be extended to a much larger period of time.
The solution could even be a one-time use fuse, isolating the battery completely. Given the option, I think most owners would rather have to replace a fuse than a $40k battery.
Yes you woudl have though that this is not exactly rocket science. Or have a mechanical switch to isolate the batery coudl this be conected to the Parking Brake.
Jermy Clarkson must be pissing himself laughing over this
LiIon cells have virtually zero self-discharge. It is the battery management system that contributes nearly all of the self-discharge to a LiIon battery. You could have such a relay, but it would require some additional tools to recover from such a state (needs to get the BMS in a happy state, or the BMS itself must have the ability to charge the battery from an unknown state).
This all would seem to make sense to install though, it's far better to have a pack that needs a reset in the shop then a brick, esp. as the battery pack in the model S will make up nearly all of the resale value of the vehicle.
Perhaps the most straightforward fix would be to simply refrain from drawing any current at all from the vehicle's main battery while parked. The alarm and any other standby processes should run from a 12-volt motorcycle battery or something, which is recharged during driving, and can be jumped like any other car battery if allowed to go dead.
That wouldn't fix the Li-ion self-discharge problem completely, but it could provide as much as a few months' worth of margin.
In any case it's batshit insane to leave early adopters stuck with a $40,000 bill for your lack of engineering foresight. That was the real surprise in the article.
"In at least one case, Tesla went even further. The Tesla service manager admitted that, unable to contact an owner by phone, Tesla remotely activated a dying vehicle’s GPS to determine its location and then dispatched Tesla staff to go there. It is not clear if Tesla had obtained this owner’s consent to allow this tracking5, or if the owner is even aware that his vehicle had been tracked. Further, the service manager acknowledged that this use of tracking was not something they generally tell customers about."
--
That screams class-action to me if Tesla can really track without knowledge of the owner AND will mean that I have absolutely zero interest in purchasing one till this is addressed.
I'm pretty sure they have been open about this. At least I remember reading this somewhere on their website. I think it was part of their 'product testing' program or something, where you would allow Tesla to track everything to gather data for their purposes to make the car better.
Class action my ass; OnStar can kill a car remotely whether you have the service or not. Why would I be shocked my $109K luxury electric sports car can report its location back with the rest of its remote telemetry?
The article explains that it doesn't have power to turn on "tow mode" - so the wheels remain engaged to the now dead electrical system, effectively locking them in place.
Why can't you plug the car in, and switch on tow mode?
Even a laptop with a dead battery works fine when plugged in. I'd venture to say that a tow truck's alternator should be enough to disengage the wheels. Sorry, but this is just crappy engineering.
Unlike a laptop, the Tesla was never designed to be run while plugged in. Combined with the fact that they arent designed to hit zero battery. This is an easy oversight of design, where the laptop can run directly off of wall power not due to fix the problem of a dead battery, but to provide less stress on the battery while being used and plugged in. A usage case that does not exist under normal usage of a tesla.
Additionally. Do we know that it is actually impossible to engage tow mode while plugged in? That still doesn't solve all cases of having to manually move it.
Failing open would be bad, a "unscrew this small panel and pull this switch" would be fine.
My car is old Saab and there are places to move aside bits of trim to manually operate the sunroof and fuel tank cover if the battery is completely gone.
They may have them, I'm not rich enough to buy a brick that big. But from what I've noticed in friends and family, most younger people don't even realize they're there. "Isn't that what P is for?". It makes me feel old driving a manual transmission and knowing what all of those things are for.
It's probably around the same in "normal" cars today. If you just have a car in park it won't move until you move it out of park, the catch is in gas powered cars, even if the battery is dead you should be able to put it in neutral to get it towed. In electric cars when the battery is dead, well that's all you have, so you can't get the gear into neutral to make it at least rollable.
Sounds like a design failure with what little transmission the roadster has, at least with the parking prawl not having some sort of mechanical deactivation.
Towing shouldn't be a problem, tow trucks carry dollies that can be manually inserted under tires. It takes like 5 minutes. I guess there are probably some limits on speed and range.
I would like to see Tesla's response to this. I was going to pre-order a model X, i won't be now, until I know I won't be tracked and the car won't brick itself.
I've bricked a number of MacBook Pro batteries this way but (A) Scale is obviously different - only $100, and (B) Genius Bar came to the rescue - even though it really was my fault, they covered it under warranty.
Yeah, I've been told it falls under the standard AppleCare warranty if this happens to anyone. (Likewise with fraying of charger cords).
Personally, I don't see why it's "your fault". I've seen it happen many times, all you need to do is let your computer drain completely and leave it for a few days (not months as some people have stated in this post). Although I'm sure it says something about it in the manual somewhere, it's hardly common knowledge that this is something you need to be careful of.
I'm much more in favor of hundreds of millions of govt money going towards 50-100MPG+ electric/gas hybrids than all electric at this point.
Limited range, hard to "refuel", and now the very real possibility of bricking. I think we are still a long long ways away from practical all electrics.
I'd prefer the government stay out of it all together. Producing vehicles isn't what the government is for.
Second, using a 2500 pound car to transport a 150 pound person 15-20 miles to work every day is incredibly inefficient any way you look at it. If the government is going to be involved at all, it should be to promote walking, cycling, and public transportation. Researching more efficient cars is like trying to replace arsenic in drinking water with mercury - maybe it's not as bad, but it's still bad.
Third, if people were serious about saving the environment and reducing pollution then they'd start living closer to the places they need to go, and stop driving so much altogether. They're not doing that, so I don't think the interest is there.
We'd be far better off if government weren't subsidizing the automobile at all. Subsidizing mass transit to ameliorate the effects of subsidizing the automobile makes no sense.
I don't think it needs to promote walking either. Most people are perfectly capable of understanding their own situations if we don't hide the costs and if they are allowed to learn from their own mistakes.
It would be proper to tax things that have negative effects that aren't paid for, such as pollution.
The main government subsidy for efficient automakers that I'd like to see is a commitment to purchase certain numbers of vehicles for federal fleets if they meet specific performance goals (including price). Same thing with state/local (possibly with some federal subsidy of local purchases of more efficient vehicles).
Ideally without specifying how to make them more efficient, just overall cost per expected miles/yr (which would probably give natural gas vehicles the best pricing right now).
And I'd be opposed to that. The federal government is so bloated, they probably have enough vehicles for the next ten years if they were to stop doing all the things not authorized by the Constitution.
Efficiency is not the only consideration when buying a vehicle. I, personally, don't want a vehicle that sacrifices safety for efficiency.
The government shouldn't be using pork or other inducements to bias the market towards one consideration. Consumers knows their own needs.
If government wants to promote efficient, it should start by being less wasteful itself. Right now its the worst example in human history.
Elsewhere in the thread I calculate the life support draw at 29 watts from available data (53kWh battery, 11 weeks to idle to empty). I think you can afford the $100 if you have a Tesla.
"The article indicates that a 100 foot cord connected to a standard outlet does not provide enough power to prevent a Tesla car from discharging..."
Pretty sure they say that to make sure people don't just use any old cord. A 24 AWG cord with 66% voltage drop as the low end would change your cost analysis radically.
You probably meant 4 AWG, a 100' of 24 AWG cord has about 2.5 ohms of resistance in it. Since power dissipation is exponential with current pulling even 2 amps through it would have the wire trying to dissipate 10 watts and that would represent 100mW/foot, easily enough to raise the temperature of the copper to the point where it would be too soft and break.
Did you try measuring the power at the wall end of the cord while the heater was running? Most space heaters aren't very smart, and it wouldn't surprise me if the draw varied wildly depending on the power supply and how warmed up the heater is (I know mine will go between 1 and 1.5kW plugged straight into the wall as it warms up).
I'd be surprised if a 100-foot extension always consumed 850 watts.
This is based on a wrong premise, that 900 watts is needed to keep the thing from losing charge, derived from vague anecdotal evidence and not supported in any way by technical fundamentals. If it was true, the 85 kwhr battery pack would last less than 3 days when the car was unplugged.
The actual number is probably more than an order of magnitude smaller.
This is akin to leaving the headlights on when the car is turned off in a regular car. You're asking for trouble. (though not to the tune of $40,000)
When the car is turned off, there should be some kind of indication of how long it will take to brick the thing. If that indication is days rather than weeks, it should yell at you. Loudly. At least that way all owners will know of the threat. The car will educate them. (important, because they probably won't RTFM)
Although I'm sure you could still end up with the odd user who leaves the car with a three week brick time, receives no loud warning because of the significant charge remaining , comes back five weeks later and curses Tesla.
They are comparable in that they both have to do with batteries and something you have to think about when you leave your car. In one case the consequences are much worse, but the general idea is the same. When you leave your car, you could mess up your battery if you aren't thinking.
Yes, true, read it now - I usually always read the comments first to know whether an article is worth reading, but commenting before reading is not smart...
I would point out that both the Model S and X may very well have the circuitry to completely disconnect the cell pack at something below 10% actual charge (not displayed charge). I'm also really wondering how much of this is self discharge, and how much of this is poor load control of the standby electronics.
Kind of crazy that for the price of just a new battery, you could get a lower class Audi or BMW. Really put the overall "electric" technology in perspective for me.
This article didn't sit well with me either. All the examples were completely anecdotal, came from an anonymous source (a "regional service manager"), and there are no citations. Footnote 1 references a "written Tesla report" but that's hardly a citation.
It may be that there is a real issue here, but I would like to see it corroborated by some actual evidence.
The real solution to this problem would be for tesla to setup "anti-brick" charging stations, install google's self-drive system on their cars, and program them to drive themselves to the nearest station and charge themselves if there is a risk of bricking ;P
A lot of people have picked at the "it won't charge through a 100-foot extension cord" statement. While I have no idea if this particular statement is true or not, it certainly wouldn't be unexpected behavior for a power management system.
Modern charging and power conversion systems are designed to operate under specific use cases. When the Tesla charger first sees line voltage, it likely does some quick testing to see what kind of supply it's hooked up to, for example by trying to take 15 Amps and monitoring the line voltage. If the voltage sags too much, then it might back off to 12 Amps; after that, it probably just shuts off. The reason is that all of the AC/DC conversion circuitry is designed to operate with maximum efficiency at a certain input power; if the system can't deliver that power, then it's just going to shut down and assume that there's something wrong with the line.
Note, this does not mean that the battery requires 1kW continuous power to stay charged. In plugged mode, the car will switch the charger on and off every few minutes (if it's at all like a laptop or phone) and draw down the battery ever so slightly in between. This is the most efficient way to operate, and is much better for the battery than constantly stuffing it with a trickle of current.
If you want to see this in action on a consumer electronics scale, try plugging your iPad into the USB extension port on an iMac keyboard -- it will kindly let you know that it's not charging, and it will happily sit there and run its battery down to the cut-off point while plugged in.
This is a good point, but to use the iPad as an example, "not charging" actually does in most cases charge very slowly. It takes what it can and provided its in standby, this is usually enough to ever so slightly charge. In the on position, it will discharge more slowly than battery alone.
The point is "optimal charge" or "complete destruction of the battery without warning" might not be the only two, or best choices available. "The best we can do with 500 watts" might be a better choice.
If you leave a gasoline engine car unattended for a while, it becomes a brick, too -- you need to flush the fuel, replace the seals, etc. True, it takes more than 11 weeks, and you can usually put the transmission in neutral to tow it.
This is a big problem, though. If anyone has a spare Tesla and would like someone to take care of it, I'd be happy to keep your car garaged and energized, and will only drive it 200 miles a week. :)
Don't forget the battery, leave a 'normal' battery through a few months and it's dead. What happens to a normal car once all the fuel is drained? Coolant? Oil?
How did these design flaws make it out of engineering?!
You can comfortably leave a regular car alone for 6 months and when you return at worst the battery will be flat and there'll be some rust on the brake pads. I regularly do this to my poor old diesel SEAT. Even if the battery is flat I can either bump start it, or worst comes to worst, buy a new $50 battery.
Diesels are a fair bit more tolerant, and low end cars are actually much more robust than performance cars. Try leaving a dodge viper unattended for 6mo.
I drove a diesel land cruiser (lm78) which had been sitting on an airfield unused for years. Aside from needing tires and a battery (and wiper blades) no problem. Even the fuel was ok.
Yeah -- probably tires go first, and that still doesn't make it inoperative, just worse performance. And you could buy several new cars for the cost of the Tesla battery pack.
While a lot of this accurate and something to consider, the author of this article fails to mention anything about Tesla's unique service/support model that they plan to roll out with the Model S. Tesla also mentions a "five-minute battery swap" available on their upcoming vehicles as well as "Tesla Rangers" that will come to your vehicle in the event that it dies. It seems to me like this is a small problem that the author is blowing out of proportion.
It seems this would be a small problem if Tesla informed their owners about it clearly (and adding a decent status display to the car to warn when it's not charging enough/how long until full battery depletion). As it seems now, Tesla owners are liable to the tune of $40K for doing something they don't know is bad.
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[ 2.8 ms ] story [ 251 ms ] threadSince you haven't done that, I find it more likely you have no clue what you're talking about.
Rather than brick the battery, if it is parked and below a certain level, release a normally open relay that completely disconnects the BMS from the cells. Recovering from this state would require special charging and recalibrating of the BMS (possibly done at a shop) but it would be better than bricking the pack.
Rather than brick the battery, if it is parked and below a certain level, release a normally open relay that completely disconnects the BMS from the cells. Recovering from this state would require special charging and recalibrating of the BMS (possibly done at a shop) but it would be better than bricking the pack.
What good does a "mini engine" do? You can't turn it on automatically, that's an enormous safety risk and would never make it past insurers or the government, and it can only last as long as its fuel holds out, again you're just delaying the inevitable. Solar panels don't help if you're parked in a garage, which is where most people park their fancy roadsters, and they'd have to be huge to maintain the charge anyway.
And absolutely none of this contradicts my original point: It's a technological limitation. This is how batteries work. You're not proposing a solution, you're proposing unworkable band-aids.
Some kind of chemical change occurs in Li batteries when completely discharged.
"Overdischarge supersaturates lithium cobalt oxide, leading to the production of lithium oxide...deep discharge may short-circuit the cell, in which case recharging would be unsafe."
and
"Overcharge up to 5.2 Volts leads to the synthesis of cobalt(IV) oxide...if overheated or overcharged, Li-ion batteries may suffer thermal runaway and cell rupture. In extreme cases this can lead to combustion."
http://en.wikipedia.org/wiki/Lithium-ion_battery
The possibilitiy of thermal runaway or fire from overcharging is actually fairly likely with Li+ ions, since they will react with any non-inert substance.
The short circuit caused by undercharging can affect other cells in the pack, leading to overheating and combustion.
As its £90 for a new one, I just leave it plugged into the wall now.
Dave
I bought a new laptop, so closed down my old Macbook, and stuck it away.
A few months later, I found I wanted to grab file from the old macbook, and noticed it wouldn't run from battery. It'll work fine plugged in, but the battery is registered as full discharged, and the Apple page says "Buy a new battery".
The other thing to consider is that as the voltage drops, so does the leakage current.
Really, this whole thing could be solved by putting a tiny solar panel on the back dash.
Even my iPhone can turn turtle to protect its battery when it gets too low.
Also how much power does it take to keep the damn thing plugged in? The article indicates that a 100 foot extension cord isn't enough just to break even and the car discharges even when plugged in. A 100 foot cord of cheap 16 gauge wire can still supply almost 900 watts before the voltage drops below 100v. So it uses a kilowatt just to stand-by without even charging? That's one hell of a power vampire.
I think maybe they should spend a bit more time on the fundamentals and a bit less time on fancy bird-wing doors if they want to have a real product. The real car of the future is just a big dumb tray full of indestructible nickle-iron batteries and 4 wheel-hub motors bolted to the corners.
http://www.teslamotors.com/goelectric/charging
Using 120V @ 15A, you get a charge rate of +5 miles (of range) per hour. Obviously not the optimal solution, but not a net negative either. Adding a 100 foot extension cord isn't going to diminish the available current enough to result in a net negative, so either the owner had additional electrical issues, or simply failed to plug it in and is making up excuses.
Additionally they quote it's happened 5 times... by an un-named service manager.
It looks like they switched from ignore/mock to attack. He's getting somewhere.
First they ignore you, then they laugh at you, then they fight you, then you win. --Gandhi
Its possible that the Tesla simply won't charge at all if the current or voltage on the line becomes too low. In this case, it would be "plugged in" but not charging.
Edit: Lets figure it out: Range=244mi. Battery capacity=58kWh. So: 5 miles takes 1.086kWh. 10% is lost in chemical conversion so we really need 1.207kWh for those miles. We pull at a rate of 1.8kWh/h from the plug. So 600 watts or so is lost elsewhere. We know the "always on" battery cooling system alone takes around 150 watts. Its not that far fetched.
Edit: I deleted my comment below where I calculated the cost of keeping the car on standby because I don't think I made clear enough (and didn't want to type it all twice) the difference between the actual discharge rate of the battery and the amount of power required at the charger to stop it. It just seems to take a lot of power at the charge port before any gets to the battery. The battery seems to discharge at an average rate of just 30 watts, but it seems to take a much, much greater amount of power input to prevent this and failing to provide this power has dire consequences. Why?
Clearly there is about 20 times that much power available at the end of a 100 foot extension cord in a standard household outlet.
Failure modes available:
• Was not actually plugged in.
• Was unplugged then plugged back in much later, possibly unbeknownst to owner. (Someone in my household unplugs my DVR to use an outlet. Grr.)
• Was on a switched outlet. (I once bought a new drill over that. Who knew one of the duplex outlets was switched and the other not? But the new drill wasn't $40k.)
• The Tesla charger could have a cutoff where it stops charging if unable to pull X amps where X is somewhere between 7 and 15. This could be either intentional or unintentional. Brown out protection circuitry, if needed by the design, could do this. They also might fear they are setting your house on fire by dropping 800+ watts somewhere in a wall and shut off.
• Broken charger.
• Broken extension cord.
Which means you have a point. If the owner in question plugged the Tesla supplied 120v cord in to an additional 100-foot, 16 gauge cord, they might have a net loss situation on their hands.
This is probably necessary to achieve UL rating.
Not necessarily. This might help, but the battery will also have self-discharge, meaning that it can lose charge without being connected to any load at all. If you get the charge down low enough, and then wait long enough, then even a full disconnect from the system won't help.
"The Tesla manager called me to warn that my car was in trouble" is a much better customer experience than "my Tesla broke down, and cost $40k to fix".
Cars used to have the same problems with oil changes. This got better, as customers were educated (at the cost of a lot of cooked engines), and cars were able to warn their owners, and run for longer without oil.
Creepy? I'm more worried about the app-of-the-day sucking down my iPhone contacts. THAT I find to be more personal than my vehicle location.
In both cases though it's not the action so much as it is the fact that you weren't able to opt out of it, or in many cases you aren't even aware of the possibility of it happening.
It's the same violation, and in both cases it's equally creepy. Apple got called out and did something about it. What will Tesla do?
I don't know anybody in their right mind who would say no to that.
Small portable gadgets using LiPoly batteries (which I assume the Tesla is using) can be left for months or years without charging, and then nursed back to life. If sufficient charge is left in them, and the circuitry is smart enough to recognise that the battery's about to die, the time before complete discharge could be extended to a much larger period of time.
The solution could even be a one-time use fuse, isolating the battery completely. Given the option, I think most owners would rather have to replace a fuse than a $40k battery.
Jermy Clarkson must be pissing himself laughing over this
This all would seem to make sense to install though, it's far better to have a pack that needs a reset in the shop then a brick, esp. as the battery pack in the model S will make up nearly all of the resale value of the vehicle.
That wouldn't fix the Li-ion self-discharge problem completely, but it could provide as much as a few months' worth of margin.
In any case it's batshit insane to leave early adopters stuck with a $40,000 bill for your lack of engineering foresight. That was the real surprise in the article.
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That screams class-action to me if Tesla can really track without knowledge of the owner AND will mean that I have absolutely zero interest in purchasing one till this is addressed.
If a service manager could access the location information I'd imagine quite a few other staff at Tesla could too ...
Additionally. Do we know that it is actually impossible to engage tow mode while plugged in? That still doesn't solve all cases of having to manually move it.
Which is actually an amusing thought. Perhaps they could ship them with really long extension chords, just enough for a city-commute...
Also, it'd be neat if you could attach to the wires for buses that are in many major cities.
My car is old Saab and there are places to move aside bits of trim to manually operate the sunroof and fuel tank cover if the battery is completely gone.
Elon has a bit more work to do.
There are also flatbed trucks.
Personally, I don't see why it's "your fault". I've seen it happen many times, all you need to do is let your computer drain completely and leave it for a few days (not months as some people have stated in this post). Although I'm sure it says something about it in the manual somewhere, it's hardly common knowledge that this is something you need to be careful of.
Limited range, hard to "refuel", and now the very real possibility of bricking. I think we are still a long long ways away from practical all electrics.
Second, using a 2500 pound car to transport a 150 pound person 15-20 miles to work every day is incredibly inefficient any way you look at it. If the government is going to be involved at all, it should be to promote walking, cycling, and public transportation. Researching more efficient cars is like trying to replace arsenic in drinking water with mercury - maybe it's not as bad, but it's still bad.
Third, if people were serious about saving the environment and reducing pollution then they'd start living closer to the places they need to go, and stop driving so much altogether. They're not doing that, so I don't think the interest is there.
I don't think it needs to promote walking either. Most people are perfectly capable of understanding their own situations if we don't hide the costs and if they are allowed to learn from their own mistakes.
It would be proper to tax things that have negative effects that aren't paid for, such as pollution.
Ideally without specifying how to make them more efficient, just overall cost per expected miles/yr (which would probably give natural gas vehicles the best pricing right now).
Efficiency is not the only consideration when buying a vehicle. I, personally, don't want a vehicle that sacrifices safety for efficiency.
The government shouldn't be using pork or other inducements to bias the market towards one consideration. Consumers knows their own needs.
If government wants to promote efficient, it should start by being less wasteful itself. Right now its the worst example in human history.
EDIT: Wow, apparently this is pretty typical and expected as per this calculator: http://www.csgnetwork.com/voltagedropcalc.html
Pretty sure they say that to make sure people don't just use any old cord. A 24 AWG cord with 66% voltage drop as the low end would change your cost analysis radically.
[1] http://www.cirris.com/testing/resistance/wire.html
Minor nitpick: power is proportional to the square of current (e.g. P=I^2), not exponentially proportional (which would be something like P=e^I).
I'd be surprised if a 100-foot extension always consumed 850 watts.
The actual number is probably more than an order of magnitude smaller.
When the car is turned off, there should be some kind of indication of how long it will take to brick the thing. If that indication is days rather than weeks, it should yell at you. Loudly. At least that way all owners will know of the threat. The car will educate them. (important, because they probably won't RTFM)
Although I'm sure you could still end up with the odd user who leaves the car with a three week brick time, receives no loud warning because of the significant charge remaining , comes back five weeks later and curses Tesla.
The two situations are not at all comparable.
With many of these vehicles in California, I shudder to think how many might brick just because the grid gets broken by an earthquake.
But yes, $40k is a lot of money and there are many options--including electric drive.
It may be that there is a real issue here, but I would like to see it corroborated by some actual evidence.
Modern charging and power conversion systems are designed to operate under specific use cases. When the Tesla charger first sees line voltage, it likely does some quick testing to see what kind of supply it's hooked up to, for example by trying to take 15 Amps and monitoring the line voltage. If the voltage sags too much, then it might back off to 12 Amps; after that, it probably just shuts off. The reason is that all of the AC/DC conversion circuitry is designed to operate with maximum efficiency at a certain input power; if the system can't deliver that power, then it's just going to shut down and assume that there's something wrong with the line.
Note, this does not mean that the battery requires 1kW continuous power to stay charged. In plugged mode, the car will switch the charger on and off every few minutes (if it's at all like a laptop or phone) and draw down the battery ever so slightly in between. This is the most efficient way to operate, and is much better for the battery than constantly stuffing it with a trickle of current.
If you want to see this in action on a consumer electronics scale, try plugging your iPad into the USB extension port on an iMac keyboard -- it will kindly let you know that it's not charging, and it will happily sit there and run its battery down to the cut-off point while plugged in.
The point is "optimal charge" or "complete destruction of the battery without warning" might not be the only two, or best choices available. "The best we can do with 500 watts" might be a better choice.
This is a big problem, though. If anyone has a spare Tesla and would like someone to take care of it, I'd be happy to keep your car garaged and energized, and will only drive it 200 miles a week. :)
How did these design flaws make it out of engineering?!
I drove a diesel land cruiser (lm78) which had been sitting on an airfield unused for years. Aside from needing tires and a battery (and wiper blades) no problem. Even the fuel was ok.
Also, a car that smart should be able to alert you in some way.