30% capacity loss is generally considered EOL for battery packs. (And that typically happens at 1000 complete charge-discharge cycles.) The Volt should have gone 1000 * 380 miles = 380K miles before hitting that.
On paper, I wanted a Leaf over a Volt, but the real world difference shows that differing battery technology still matters a lot. I dunno how Nissan built such a bad pack but there you go.
> The Volt should have gone 1000 * 380 miles = 380K miles before hitting that.
And might have if not subjected to worst-case conditions which EV drivers do not subject their cars to. What are the real-world results in terms of battery capacity declining? They don't seem to be anywhere near that.
So again, as I already said in my first comment, I'm not seeing how this is really relevant - much less some sort of fatal proof.
Yes. It's foolish to compare the cost of consumable gas vs consumable electricity.
Much better is consumable gasoline versus battery depreciation. Electricity costs nearly disappear.
This was an old adage among the homebrew EV crowd: buying a battery pack is pre-paying for your fuel for the next N years.
The Powerwall is about 35 cents per KWh, assuming it can handle 1000 full cycles. ($3500 for 10KWh capacity.) A decent EV can get 5 miles out of that, so the battery depreciation is 7 cents a mile. That's a multiple of the electricity cost, which is about 2 cents a mile if you don't try for any time-of-day billing.
 This is just my best comparison of the actual cost of a Tesla battery.
This thread is rapidly entering territory where only a comprehensive comparison of TCO will suffice (not that those won't be biased either way), but the price of the battery is only one part of the price of the car. 70k$ amortized over 300k miles is still 23¢/mile.
I understand Tesla's luxury-first strategy and hope the future part will pan out, but at the present time it is very weird to be making a cost based argument.
If you can amortize the battery cost over the miles driven, electric cars ought to be cheaper than gas cars. Less maintenance (no spark plugs or oil changes), less consumables, and the purchase price is about the same (see my first phrase).
If Better Place had worked out, it would have let people shift the battery ownership elsewhere. But it didn't.
You are planning to charge the thing overnight and use it exclusively during the day, nearly exhausting it each time?
The battery is going to wear out well before 10 years. If you oversize your battery so you are only pulling out half the charge in the battery, you can probably get 1500 cycles out of it. That's still less than 5 years.
(This is a common pattern if you are trying to price-compare an electric car to a gas car. For the electric car, the electricity cost is a rounding error compared to the capital cost of the battery, so you can just about assume electricity is free, and worry instead about how long the battery will last.)
You will get a much bigger bang-for-the-buck by demand-shifting: if the biggest load is cooling your building in the heat of the day, run the A/C overnight to superchill a heat sink that can be accessed during the day. No battery installation needed.
 Toyota did this with the Prius. They purposefully did not use the full range of the battery because they wanted the battery to last 7+ years.
That's a good question, and it makes a big difference.
> That you can still get 20% capacity levels in year 10, or that it will still turn on? This might be considered "normal wear and tear."
Given that you can optionally warranty it for an additional 10 years, I doubt it's nearly that bad. If people are confused as to how they how they hope achieve 10 years reliability, and they are willing to warranty 20 years, they must have something up their sleeves.
> 3000 deep cycles is really pushing what the industry knows to be state of the art
I suspect that the powerwall's true capacity is higher than it's rating, and it uses that reserve so it's not doing deep cycles, similar to another commenter's assertion to how the Prius gets it's 7+ year rating,
> Maybe they are just taking the economic chance that most people won't be deeply cycling these batteries, and planning to do replacements for those who actually put it through its paces.
I think a combination of most users not fully cycling every day, extra reserve capacity to keep it from deep cycling, and some subset of people not using failing warranty conditions may all contribute.
For each person that load-shifts, it slightly reduces the payoff for the next person to load-shift.
In the UK, the peak demand is already in the evening, because solar has eaten the cheap lunch during the day (which it was supposed to do, but it means that each additional solar panel is going to have a harder job paying for itself). And the demand difference between low and high is about 30GW to 40GW.
Great point about marginal benefits of load shifting. I do think we're so far from that reduction being significant at this point that it's worth attempting.
I believe peak demand in most non-industrial areas is already evening, because residential areas tend to have less efficient energy use than commercial spaces due to density, and everyone is home at the same time, often doing energy intensive tasks such as cooking, using the A/C, opening the fridge. I heard from someone at a power company that advertisements during the Super Bowl are a major issue, because everyone opens their fridge and flushes the toilet at the same time, and power supply has to spike for 3 minutes and then return to normal.
When the used batteries start piling up, it's best for tesla if this system is already in place. Entirely possible that this will be new and subsidized batteries initially. They will need to find a use for the old car batteries.
Does your insurance company allow you to keep one liter of gasoline in your garage? It has the same energy content as the Powerwall, is insanely flammable, is frequently implicated is home fires, and regularly causes human deaths.
(Ok, a burning lithium battery will release more energy than its storage capacity, but I'm not finding a nice reference, Tesla knows all about containing cells to prevent chain reactions, and one liter of gasoline is still enough to burn down your whole house.)
Gas fumes are very flammable, but the gasoline itself will flow down and out of my garage, and the fire would be very easy to contain with a simple garden hose.
A gas can also will not light on fire just because it gets hit with a car. It would take malicious use of a gas can -- splashing it on a wall and then lighting it on fire -- to match the default configuration of a Powerwall.
While true for lithium fires, a venting lithium-ion battery is not a typical lithium fire.
According to the MSDS for lithium ion batteries, fires involving them can be extinguished with a typical ABC fire extinguisher.
Lithium batteries (not the rechargeable kind) are the ones that need a class D extinguisher.
> CO extinguishers, halon or copious quantities of water or water-based foam can be used to cool down
burning Li- ion cells and batteries. Do not use for this purpose sand, dry powder or soda ash, graphite powder or fire blankets.
> Extinguishing media Use water or CO2 on burning Li-ion cells or batteries
It's common advice not to leave rags that have gasoline on them sitting in your garage because in enough heat the fumes from the evaporating gasoline will combust. Gasoline is very volatile, we've just gotten fairly good at managing it.
Moderation is pretty weird in this thread. I got voted down for pointing out that the US power grid is likely to experience problems when entire residential neighborhoods full of Tesla owners try to charge their Model S at once.
I don't think many people around here understand (a) just how efficient gasoline really is at storing energy, and (b) just how much energy is used by a typical passenger car.