The Zebra battery has it's own problems, poor efficiency from high power usage to keep it in a molten state, and worse energy density than most lithium last I knew.Originally Posted by eledille
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I own an EV and know that I must keep it charged
I own an EV but it wasn't made clear to me that I must keep it from being discharged
I don't own an EV but knew that you had to keep the battery from going flat
I don't own an EV and didn't know that you needed to keep them charged
The Zebra battery has it's own problems, poor efficiency from high power usage to keep it in a molten state, and worse energy density than most lithium last I knew.
The Zebra is very different from lithium-ion, but may make a lot of sense in certain applications. It's currently not power dense, but that's not surprising given the amount of research that has gone into it it vs. lithium ion. I think it might be improved a lot. It is relatively energy dense, though. The Think City Zebra pack is approximately as energy dense as the Roadster's complete battery pack at 28.3 kWh/250 kg = 113 Wh/kg versus 53 kWh/450 kg = 118 Wh/kg. Efficiency is very poor if the car spends a lot of time standing still, but losses during use becomes heat which is contained inside the pack, so the battery does not need to expend extra power to stay hot if it is used often. It degrades much more slowly with time and cycles than the Roadster battery. I agree that lithium-ion is more promising, however.
What I'm trying to say is just that different battery chemistries behave differently. Some don't mind being stored at 0 volts while this instantly destroys others. Some have low self discharge, others high. Some need to be hot, others like to be cool, and so on. They are simply different. Even different versions of a single chemistry can behave very differently, Altairnano being one example.
As an EV owner you really want to keep your particular variant happy, so reading the manual is a must
Yes, he took advantage of the unfortunate use of the word "leave" by Elon, and neither person actually mentioned the phrase "memory effect," although it's clear from Jay's comments that's what he was talking about.
Going forward, does it even matter?
The world loves to be deceived.
Ignoring that the Model S addresses this problem.
This sounds like one of those, What If I want to drive to my great gramma's house?" questions. The answers are as easy as "rent a car" or Have someone check on your car.
I mean, if an EV owner is in a horrible accident and is in a coma for a year maybe they have a dead EV in the garage. Meanwhile they might have lost the house, wife and job. Stuff happens. Electric cars are not perfect, just more perfect than gasoline cars.
Last edited by vfx; 02-29-2012 at 10:18 AM.
The world loves to be deceived.
Then, when the car gets to 5% SoC you get a call (or an email?) from Tesla. You phone (or email) a neighbor or friend and ask them to check on it. I always leave a spare key with a trusted neighbor.
If you are in a coma for two months, you have much more serious problems than the car. But if there is someone who checks your messages (your wife?) they'd get the message and be able to deal with it. If you are hospitalized but conscious, you get the message one way or another.
The trade-off is that Tesla uses a battery type with greater energy density by both weight and price, but the "cost" is that it requires more care, and therefore more power, than other battery types (some of which weren't even available when the Roadster was designed). With LiFePO4 the Roadster pack would have needed less care, and could have been designed to endure years (?) without being plugged in. But the car would have cost more and had less range. Trade-offs.
The relatively shorter safe no-plug time is the "price" of getting the most range and keeping the cost down.
BTW and FWIW, I took a long vacation, left the car plugged in in Storage mode, and IIRC the pack was at about 20% when I returned home. This was plenty to do some shopping immediately, and the next morning the pack was at a "full" Standard charge. (I had no reason to charge it immediately, so let it wait for its usual midnight start time.
A related question: How much money do you want to spend to reduce the likelihood of an event which is already extremely unlikely? If a different design would have enabled to car to sit unplugged for a year but would have raised its price by $10,000, would it be worth it to protect the car against the event that you are in a coma for two months AND your circuit-breaker trips AND you have nobody checking messages who can deal with the car when Tesla tries to notify you? I think it's a case of dreaming up extremely unlikely scenarios to justify adding a possibly expensive additional fail-safe. The guy who started all this simply neglected to plug in his car. The lesson for the rest of us: Plug in your car.
But, OTOH, if a simple software update can extend the safe unplugged time without making a different fail route more likely, then I'm all for it.
It doesn't. I was just wondering if people with a car before #340 signed the agreement then that would make his already weak argument even weaker because his source (business partner and friend) would have signed it too.
Well said. There really is only so much you and Tesla can do to prevent the battery from becoming ruined from lack of charge. Plugging it in is of course the first step. Anyone can imagine worst case scenarios where 5 events would need to happen for your car to lose power but as you said, at what cost? You could give your neighbor $20 to check your car once a week to make sure if was still plugged in an charging if that assurance was enough for you. There are low tech solutions to the problem if the power grid, charger, car and planet alignment all are off that day.
Last edited by dsm363; 02-29-2012 at 10:31 AM.
Or have a 700 mile range or charge in 2 minutes or carry a sheet of plywood build a guestroom or stockpile for the coming apocalypse ?A related question: How much money do you want to spend to reduce the likelihood of an event which is already extremely unlikely? If a different design would have enabled to car to sit unplugged for a year but would have raised its price by $10,000, would it be worth it
The world loves to be deceived.
I just see this as an issue of relative risk. There appears to be a tiny risk of bricking it if I'm stupid enough, but I get withdrawal after just a couple of days if I haven't driven it, so the idea I'd neglect it for months on end is preposterous. I'm not remotely afraid of this happening.
A far more likely scenario is my Roadster gets written off by a lamp post or driven into by some idiot. Now that's a risk I spend effort worrying about. Next issue please.
Speaking of which - that is a real scenario - a wrecked car sitting in a salvage or repair lot with the battery/pack heading toward oblivion.
Hopefully someone (Tesla themselves?) is able to go rescue packs of otherwise disabled cars. Lets say for instance that the charge port got damaged in an accident.
Neglect and/or forgetting is one thing, but what about those rare situations where you are unable to charge even if you wanted to?
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