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There's an interesting thread from the Tesla Motors club, with lots of input from actual Tesla owners: http://www.teslamotorsclub.com/showthread.php/13633-NYT-

by iyulaev 14y ago

There's an interesting thread from the Tesla Motors club, with lots of input from actual Tesla owners: http://www.teslamotorsclub.com/showthread.php/13633-NYT-article-Stalled-on-the-EV-Highway/page1 http://www.teslamotorsclub.com/showthread.php/13633-NYT-arti... From actual Tesla owners, the performance seen by the NYT reporter appears to be par for the course. To date most all-electric vehicles have struggled in the cold. The Nissan Leaf has a terrible time of it, with the range decreased significantly. I was honestly excited to see how Tesla S card would fare in cold weather, and how the Tesla engineers got around this problem. Disappointingly it looks like they didn't, and (anecdotally) the problem may be even worse on the Tesla S than on the roadster or even the Leaf. Bummer. To everyone comparing the cold weather performance of the Tesla to an ICE: yes, ICEs do get harder to start and less efficient in the cold. But for an ICE, that kind of cold is significantly under 0 farenheit - most of the U.S. is at a low enough latitude that temperatures like this are rarely seen and modern ICE cars will start happily without the need for block heaters and other measures. The reporter had significant trouble at temperatures around 30F which even an air-cooled car from decades ago will shrug off. We're talking about maybe 10% of the population having to take special measures during especially cold times of the year (block heaters for temps < 0F) vs >50% of the population (plugging in overnight, every day, for temperatures <= 30F). HUGE difference Another blog post which sounds a bit more horrific than the NYT experience, although the Tesla owner really takes it with a good attitude: http://andwediditourway.blogspot.co.uk/2013/02/the-not-so-ev-life.html http://andwediditourway.blogspot.co.uk/2013/02/the-not-so-ev... Other interesting information gleaned from the thread - 120V is useless for electric cars, you really have to have a dedicated circuit for them. And did I mention they hate the cold? I'm rooting for Tesla and for electric cars. But I do wish they were rated to perform at lower temperatures, and that everyone (Tesla and reporters alike) was more transparent about this. I'd rather see a few people turned off on electric cars and the rest informed and trained with the care and feeding of the cars during winter, than to see people stranded out in the cold because they weren't aware of their cars' performance envelopes.

deleted 14y ago
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insaneirish 14y ago
To be pedantic, it is not that 120 V is not enough. It's that the amount of current you need at that voltage is prohibitive because of wire sizing, which is needed to minimize resistive voltage loss and dangerous wire overheating.
- iyulaev 14y ago
  Absolutely right. I was using 120V as shorthand for "the 120V/20A circuit that we're all used to."
  - zanny 14y ago
    I don't think saying "120v isn't enough, you need to rewire your entire house" is really accurate either. Most water heaters, stoves, and some central heaters run off a merged breaker for 240v. You can easily use one of those lines for the car if you don't plan on taxing the thing the entire time (though I figure if you have 50k for a car you have 1k to add an extra circuit and wire your garage up for it). Also, 240v cars makes so much more sense in a world where 99% of people use 240v outlets, and in the US you can just oscillate two 120v's and get a usually-good-enough 240v signal.
  - iyulaev 14y ago
    I don't think saying "120v isn't enough, you need to rewire your entire house" is really accurate either. Most water heaters, stoves, and some central heaters run off a merged breaker for 240v. You can easily use one of those lines for the car if you don't plan on taxing the thing the entire time (though I figure if you have 50k for a car you have 1k to add an extra circuit and wire your garage up for it). Yes, although at least in my view part of the selling point is that we have plugs everywhere, so you have electricity anywhere right? Well, hunting around for a 240V plug is a big harder than 120V. Also, even though 99% (???) of the world is on 240V, I think the current rating on those circuits still limits power to around 2kW sustained.
    - stephen_g 14y ago
      I'm in Australia, and our power supply is 230V AC (+/- 6%) (240V was the standard before 2000, but is still within the acceptable limits). Most power outlets are 10A (max ~2300W) but I also have two 15A sockets in my house for the air conditioners (3450W - I also use one to power my coffee machine, which pulls 3200W when warming up!), and could theoretically get a 20A socket (4600W) installed. With an industrial outlet, you can get single phase power of up to 32A (7360W), but I doubt most electricians would install that for you at a house.
revelation 14y ago
ICEs are significantly less efficient at startup and until they get up to their normal operating temperatures. That's not so much a problem for long range trips, but taking multiple single-digit mile trips spaced apart in the time dimension. EVs have no problem "starting" in low temperatures. You might not be able to draw as much power for the drive train as the pack is heating up, but it's not a primordial "fuel-air-mix won't explode" problem. There is no "problem" to get around; you either risk your battery pack getting damaged or you have an active battery management system that regulates the packs temperature. That will consume power, no way around it. Now there are some conflating issues we have to consider. Tesla recently disabled in a patch the sleeping modes of some onboard components, and this vampire load might be contributing greatly to the large loss of energy reported overnight. The other is the drivers mentality; you don't drive it to the point of 5% remaining and then fuel up, thats how you do it with ICEs. Instead, you just simply plug it in whereever you can. And frankly, if you are going to keep it outside overnight at very very low temperatures (thereby forcing the battery management system to expend energy for heating), plug it into a 120V. They can (contra to your statement) get enough power from even from a 120V to keep the battery pack (and your range) at least at the same level, if not adding range. --- A side remark: I very much think this is a complete non-issue. 90% of driving is commuting, it is decidedly not long-range trips. And then this is mostly an issue of infrastructure; if there were at least 120V plugs at every parking lot, you wouldn't ever have to worry about these vampire loads. Infrastructure, since we are at it, is of course a much much bigger problem for gasoline cars; think of all the steps necessary to refine oil into gasoline and make it available at gas stations. Driving an ICE across states at the time of their advent would not have been a particularly enjoyable experience due to the general unavailability of fuel.
- majormajor 14y ago
  It's blown out of proportion for the normal use case, but I still think it was a very interesting review. I didn't expect them to be great road-tripping vehicles at this point, but was a bit disappointed by how the weather affected things. Even Musk's comments so far don't change my impression of that: so it's fine for a road trip if you make sure you don't get stuck in traffic, and make sure you never ever miss a chance to get it fully charged up, especially if the weather is cold? That's just not going to be competitive convenience-wise for long trips right now, no matter how much spin you want to put on it. The open question to me is just how fast the driver was going on the highway (90+ would make me raise an eyebrow or too), I'm not really sympathetic to the rest of Musk's claims at all. And unless he can provide some conclusive log evidence, collaborated by outside evidence, that's far more damning than what his comments so far describe, it reflects pretty poorly on the company to me. Much more poorly than the original review, since I expected that to be pretty much a worst-case scenario—and was very interested in just how well it would handle that kind of stress test. Edit: the thing that really bugs me about the response is that it's empty so far. If you've got conclusive evidence, show the evidence. Don't go all he-said-she-said in the meantime.
refurb 14y ago
The reviews from Tesla owners who have their own experience with the car in cold weather is interesting. Can anyone tell me why the car discharges when plugged into a 120V supply? It's mentioned in one of the links above and in the NYT article. I'm aware that you can't supply much current with a standard 120V supply, but why would it discharge? I would imagine at a minimum you'd have a very slow charge rate, but from these two anecdotes, it appears in cold weather it still slowly loses charge when plugged into 120V. Is the car constantly heating the battery? I could see that being the issue as engine block heaters draw a ton of current and they take a long time to heat up an engine block. I'm assuming the battery has a lot more thermal mass than a 300 lb engine block.
- ooorrr 14y ago
  It's not discharging because it's plugged into 120V. It's discharging faster from the cold than the 120V is charging, so there's a net loss.
  - lsaferite 14y ago
    I thought the cold caused batteries to slow down on discharge rate. The LiPo batteries I use for RC planes keep a charge much longer if they are refrigerated. They have a horrible discharge rate when cold though.
- hatcravat 14y ago
  I speculate that it is a interaction of several things: 1) The current firmware assumes there is "unlimited" energy available when charging, so it can keep the battery warm with little impact on charging rate (this is not a bad assumption for everything other than 120V/15A charging). 2) The current firmware assumes that the battery needs to be kept warm when charging (this is not a bad assumption for everything other than 120V/15A charging, but may not be correct for low-power charging). 3) The power required to keep the battery warm in near-zero (Fahrenheit) temperatures is nearly the same as the maximum continuous power available from a 120V/15A outlet (1.44kW, because the maximum continuous load is only 80% of the maximum load), at least initially. The firmware probably needs to be tweaked for cold-weather, low-power charging. The firmware needs to know how to estimate state of charge when the battery is colder than normal. It could probably prioritize charging ahead of heating until the battery reaches a higher state of charge.
deleted 14y ago
[deleted]
Tloewald 14y ago
Great thread. Thank you for linking it. My recurring thought as i read through it was of the iPhone first and second generation when battery life was pretty awful and you tended to carry a charger and nurse your phone through the day (much as with my first GSM cellphone). The iphone 4 had battery life to the point where you just didnt need to care any more (like my motorola razr). Problem is, Tesla doesn't have moore's law to make the car run faster on the same charge or allow more empty space for bigger batteries, so the only real solution is more charging stations and faster charging.

by iyulaev 14y ago

deleted 14y ago

[deleted]

insaneirish 14y ago

To be pedantic, it is not that 120 V is not enough. It's that the amount of current you need at that voltage is prohibitive because of wire sizing, which is needed to minimize resistive voltage loss and dangerous wire overheating.

iyulaev 14y ago
Absolutely right. I was using 120V as shorthand for "the 120V/20A circuit that we're all used to."
- zanny 14y ago
  I don't think saying "120v isn't enough, you need to rewire your entire house" is really accurate either. Most water heaters, stoves, and some central heaters run off a merged breaker for 240v. You can easily use one of those lines for the car if you don't plan on taxing the thing the entire time (though I figure if you have 50k for a car you have 1k to add an extra circuit and wire your garage up for it). Also, 240v cars makes so much more sense in a world where 99% of people use 240v outlets, and in the US you can just oscillate two 120v's and get a usually-good-enough 240v signal.
- iyulaev 14y ago
  I don't think saying "120v isn't enough, you need to rewire your entire house" is really accurate either. Most water heaters, stoves, and some central heaters run off a merged breaker for 240v. You can easily use one of those lines for the car if you don't plan on taxing the thing the entire time (though I figure if you have 50k for a car you have 1k to add an extra circuit and wire your garage up for it). Yes, although at least in my view part of the selling point is that we have plugs everywhere, so you have electricity anywhere right? Well, hunting around for a 240V plug is a big harder than 120V. Also, even though 99% (???) of the world is on 240V, I think the current rating on those circuits still limits power to around 2kW sustained.
  - stephen_g 14y ago
    I'm in Australia, and our power supply is 230V AC (+/- 6%) (240V was the standard before 2000, but is still within the acceptable limits). Most power outlets are 10A (max ~2300W) but I also have two 15A sockets in my house for the air conditioners (3450W - I also use one to power my coffee machine, which pulls 3200W when warming up!), and could theoretically get a 20A socket (4600W) installed. With an industrial outlet, you can get single phase power of up to 32A (7360W), but I doubt most electricians would install that for you at a house.

revelation 14y ago

ICEs are significantly less efficient at startup and until they get up to their normal operating temperatures. That's not so much a problem for long range trips, but taking multiple single-digit mile trips spaced apart in the time dimension. EVs have no problem "starting" in low temperatures. You might not be able to draw as much power for the drive train as the pack is heating up, but it's not a primordial "fuel-air-mix won't explode" problem. There is no "problem" to get around; you either risk your battery pack getting damaged or you have an active battery management system that regulates the packs temperature. That will consume power, no way around it. Now there are some conflating issues we have to consider. Tesla recently disabled in a patch the sleeping modes of some onboard components, and this vampire load might be contributing greatly to the large loss of energy reported overnight. The other is the drivers mentality; you don't drive it to the point of 5% remaining and then fuel up, thats how you do it with ICEs. Instead, you just simply plug it in whereever you can. And frankly, if you are going to keep it outside overnight at very very low temperatures (thereby forcing the battery management system to expend energy for heating), plug it into a 120V. They can (contra to your statement) get enough power from even from a 120V to keep the battery pack (and your range) at least at the same level, if not adding range. --- A side remark: I very much think this is a complete non-issue. 90% of driving is commuting, it is decidedly not long-range trips. And then this is mostly an issue of infrastructure; if there were at least 120V plugs at every parking lot, you wouldn't ever have to worry about these vampire loads. Infrastructure, since we are at it, is of course a much much bigger problem for gasoline cars; think of all the steps necessary to refine oil into gasoline and make it available at gas stations. Driving an ICE across states at the time of their advent would not have been a particularly enjoyable experience due to the general unavailability of fuel.

majormajor 14y ago
It's blown out of proportion for the normal use case, but I still think it was a very interesting review. I didn't expect them to be great road-tripping vehicles at this point, but was a bit disappointed by how the weather affected things. Even Musk's comments so far don't change my impression of that: so it's fine for a road trip if you make sure you don't get stuck in traffic, and make sure you never ever miss a chance to get it fully charged up, especially if the weather is cold? That's just not going to be competitive convenience-wise for long trips right now, no matter how much spin you want to put on it. The open question to me is just how fast the driver was going on the highway (90+ would make me raise an eyebrow or too), I'm not really sympathetic to the rest of Musk's claims at all. And unless he can provide some conclusive log evidence, collaborated by outside evidence, that's far more damning than what his comments so far describe, it reflects pretty poorly on the company to me. Much more poorly than the original review, since I expected that to be pretty much a worst-case scenario—and was very interested in just how well it would handle that kind of stress test. Edit: the thing that really bugs me about the response is that it's empty so far. If you've got conclusive evidence, show the evidence. Don't go all he-said-she-said in the meantime.

refurb 14y ago

The reviews from Tesla owners who have their own experience with the car in cold weather is interesting. Can anyone tell me why the car discharges when plugged into a 120V supply? It's mentioned in one of the links above and in the NYT article. I'm aware that you can't supply much current with a standard 120V supply, but why would it discharge? I would imagine at a minimum you'd have a very slow charge rate, but from these two anecdotes, it appears in cold weather it still slowly loses charge when plugged into 120V. Is the car constantly heating the battery? I could see that being the issue as engine block heaters draw a ton of current and they take a long time to heat up an engine block. I'm assuming the battery has a lot more thermal mass than a 300 lb engine block.

ooorrr 14y ago
It's not discharging because it's plugged into 120V. It's discharging faster from the cold than the 120V is charging, so there's a net loss.
- lsaferite 14y ago
  I thought the cold caused batteries to slow down on discharge rate. The LiPo batteries I use for RC planes keep a charge much longer if they are refrigerated. They have a horrible discharge rate when cold though.
hatcravat 14y ago
I speculate that it is a interaction of several things: 1) The current firmware assumes there is "unlimited" energy available when charging, so it can keep the battery warm with little impact on charging rate (this is not a bad assumption for everything other than 120V/15A charging). 2) The current firmware assumes that the battery needs to be kept warm when charging (this is not a bad assumption for everything other than 120V/15A charging, but may not be correct for low-power charging). 3) The power required to keep the battery warm in near-zero (Fahrenheit) temperatures is nearly the same as the maximum continuous power available from a 120V/15A outlet (1.44kW, because the maximum continuous load is only 80% of the maximum load), at least initially. The firmware probably needs to be tweaked for cold-weather, low-power charging. The firmware needs to know how to estimate state of charge when the battery is colder than normal. It could probably prioritize charging ahead of heating until the battery reaches a higher state of charge.

deleted 14y ago

[deleted]

Tloewald 14y ago

Great thread. Thank you for linking it. My recurring thought as i read through it was of the iPhone first and second generation when battery life was pretty awful and you tended to carry a charger and nurse your phone through the day (much as with my first GSM cellphone). The iphone 4 had battery life to the point where you just didnt need to care any more (like my motorola razr). Problem is, Tesla doesn't have moore's law to make the car run faster on the same charge or allow more empty space for bigger batteries, so the only real solution is more charging stations and faster charging.