August 22, 2007
Future Old Car Batteries To Power Houses?

An article by Chris Vernon at The Oil Drum notes we are close to the era of electric cars and that suggests to me we are close to the era of battery usage to store and provide home electricity.

The A123 Systems battery can charge to 90% capacity after approximately 2300 charges (86% after 3800) according to this graph.

These numbers are revolutionary. Even if your car has a small battery pack (plugin hybrid with 40 mile range) and you only drive it in town as an electric vehicle your battery is going to last 40x2300 miles (an amazing 86,000 miles on PHEV power alone) and the car will still go to 90% of the distance it could on a charge when new (36 miles instead of 40)! It seems the battery will outlast the life of the typical car on the road today. If your car is an electric car (with more batteries) and you can do 150 miles a charge it will be 90% as good-as-new after an astounding 345,000 miles! 2300 charges at one charge a day is also more than 6 years. The Phoenix SUT uses Altair Nano's battery and is expected to last 250,000 miles / 12+ years.

I see old PHEV car batteries eventually getting reallocated for use to store electricity for homes. Electricity collected when the wind blows or the sun shines will go into lithium ion car batteries that might have lost 30% or even 40% of their original charge capacity. But the remaining capacity will make a substantial difference to enable people to shift electric power from when it is cheap to generate to when they want to use it.

Suppose we see major volumes of pluggable hybrid electric vehicles onsale within 4 years. Seems plausible. GM is aiming for 2010 with their Volt car. Suppose it takes them till 2011. A Volt might go 20 years before its too old and its batteries at that point will still be in pretty good shape. If the Volt can go 40 miles on a charge and uses 250 watt-hours per mile (pretty close to what it will use) then the Volt might originally have 10 kwh of capacity. Well, even if it degrades 80% it will still have 8 kwh of capacity. For a house that uses 20 kwh per day the 8 kwh of storage capacity from old car lithium nanophosphate batteries would allow shifting of a substantial chunk of solar power from day time to night. Or it would allow shifting of nuclear electric power from night to day.

A big PHEV SUV will come with twice the battery capacity as a compact to drive the same difference. So the electric SUV might start with 20 kwh of battery capacity and end up with 16 kwh of capacity by the end of vehicle life. Such a battery could operate a house for a day after a power outage if the occupants became frugal with their electric usage. Throw in a second SUV and the house could go two days on the power of the old batteries.

But we don't need to wait for the cars to wear out to start using their batteries to save and use electric power. If you know you are staying home for a few days then why not plug the car into the house and use the car battery to let you grab electricity and store it in your car when it is cheap and use it from your car when the price of electricity goes up in late in the afternoon and early evening?

Share |      Randall Parker, 2007 August 22 11:14 PM  Energy Batteries

Innovation Catalyst said at August 23, 2007 9:24 AM:

I would love to live in one of those areas with time of day metering. My power is one rate, deregulated, high cost 24-7.

Greg said at August 23, 2007 12:50 PM:

"why not plug the car into the house and use the car battery to let you grab electricity and store it in your car when it is cheap and use it from your car when the price of electricity goes up in late in the afternoon and early evening?"

Because charge/discharge cycle degrades your car battery. It degrades it slighty, maybe 1/2300 or 1/3800 of its capacity, but if the entire battery pack costs $10000, it is $3-$4. So your electricity savings must be higher than that, and they aren't.

Brian Wang said at August 23, 2007 4:51 PM:

Some energy future related items.

It seems likely that a climate change bill is going to get voted on and passed with the 110th congress.
I have some info on my website about it.
The Lieberman-McCain Climate stewardship and innovation act of 2007 is quite favorable to nuclear power. A study by the Energy information administration of the DOE shows that nuclear power would almost triple to 1900 billion kwh by 2030 if this is passed. Anything like it with strong costs and caps on coal with reasonable support for nuclear means a faster move to nuclear power.

Also, the bussard fusion reactor demo seems to have finally been funded. This seems confirmed by insiders. If they make a new demo system which in 2 years confirms the big results from the last demo, then the $100-200 million for the full system could get funded. They estimate 5 years for that second project. So perhaps by 2014-2015 this could be working.

Another point is for electric vehicles. The 450 million bicycles in China are being converted to electric bicycles and electric scooters. 60 million by the end of 2007. 350 million possibly by 2011-2013. The number of scooters to cars in Taiwan is about 20 million to 5 million. So the electric scooter in China could lower the number of cars that China ends up using by 75%. China would still end up with a lot of cars, but the electric scooter could slow the move to cars, and it would be helped the inability to make efficient roads and parking for all those cars. Hopefully this will also take off in India instead of the $2000-4000 cars for India.

Pete said at August 23, 2007 4:56 PM:

Nothing wrong with the idea of giving an ol' battery some new purpose.
But with lithium it wont happen.
Firstly, lithium is way to scarce to power a significant amount of the world's cars.

It probably would be scarce enough to make it more feasible to recycle the lithium into new batteries to regain their maximum energy storage capacity. You don't let stuff linger around if it can be recycled into something more desirable.

As the world will adopt another battery chemistry for its nearly one billion cars, like zinc air for example the issue of running houses on spent batteries will be moot due to the reduced cycle life of these chemistries.

Randall Parker said at August 23, 2007 5:50 PM:


It takes 3800 charges to degrade 10%. So 380 charges to degrade 1%. So if it costs $10000 it would degrade $100 worth from 380 charges. That's about the number of days in a year. I calculate that as 26 cents per day.

Actually, it would be cost inefficient not to use it for that purpose. You've got $10000 sitting there not earning you any interest. Up your capital utilization rate.

Would you save money? It depends on two questions:

A) Will you have solar panels by then.

B) Or will you have dynamically priced electricity by then.

If you have dynamically priced electricity that costs 2.5 cents at late night and 12.5 cents per day then each shifted kwh saves almost a dime (some heat loss there). Seems like a good deal. You just have to shift 4 kwh and you've equalled your battery depreciation cost. Shift more kwh (since your battery will be higher capacity than that) and you start to make a profit.

Greg said at August 24, 2007 6:39 AM:


I calculate it differently. It takes 3800 charges to degrade 10%, and, say, 6000 charges to degrade 20% after which the battery becomes unusable as a battery for electric car, and requires a costly ($10000) replacement. That means that each additional discharge/charge cycle brings you 1/6000 closer to that unfortunate moment, i.e. at least $1.66.
I have dynamically priced electricity at $0.07 off-peak vs. $0.13 peak. So, in my case it doesn't make sense to use car battery as energy storage.
What I'd like to know about energy storage relates to Zinc-Air batteries. These are far superior to Li-Ion with respect to energy density and have a discharge rate that's good enough. But, instead of recharging, they require chemical re-processing. It is not feasible for electric transport (other than buses, garbage trucks and the like which have their parking facilities that can double as battery re-processing plants), but for utility companies it might be a good fit. Is there any activity in that area?
I also wonder why we don't hear of "quick replacement" approach to car batteries vs. recharging. One can do it the oil change style (a ramp where the batteries are pulled from underneath a car and quickly replaced with a fresh pack), or with trailer style (just carry your extra pack on a trailer and re-hook). The trailer can also provide a surface for solar cells.

Nick said at August 24, 2007 9:48 AM:

It's important to remember that battery deterioration is non-linear. If you kept the Depth of Discharge between, say, 40% and 80% you'd probably get 20,000 cycles, i.e., essentially unlimited.

Randall Parker said at August 24, 2007 5:20 PM:


A few points:

1) The original $10k battery does not become worthless once it can no longer be used in the car it came with. If it is useful for housing it will have a resale value based on the value it can be for home owners or commercial building owners or solar photovoltaic farm owners or wind farm owners.

2) 5 years after the first lithium iron nanophosphate batteries get sold they will have lower new battery prices than when they first went on sale. So replacements for original priced $10k batteries will be less than $10k. Plus, other batteries will come along such as ones built with nanotubes.

3) Especially for people who drive lower miles they might as well get better capital asset utilization by making their $10k investment do double time in terms creating value for them via saved energy costs.

4) The trade-off heavily depends on the gap between your peak vs off-peak electric prices. The gap ought to be far wider than it is now (most have no gap at all). I've come across reports where economics calculated off-peak prices in some areas below 3 cents per kwh. Regulatory reforms can make a big difference here.

5) Cheaper wind and solar should make the gap between peak and off-peak wider.

6) Zinc-air: So far I've only come across reports of its use for buses. I've come across (and did a post about) NaS for utility batteries for shifting supplies to peak hours. Some US utilities are starting to install it using a Japanese supplier.


Do we know that lithium nanophosphate is non-linear the way some other batteries are in terms of deterioration?

pete said at August 25, 2007 12:04 AM:


you ask about ways of recharging automotive zinc air.
Pull up this

and search for "quick recharge" inside the document.

While everyone seems to get hyped by the prospect of running the world's automotive fleet on lithium chemistry - some even think in future there might be enough "spare" lithium floating around in the form of old batteries...
I have to ask you guys here, do we really want to shift from one dwindling resource to another resource which is already scarce, i.e. from oil to lithium?

There is plenty of research going on in the EU, Israel, China already has the technology on the road.... Zinc air has major advantages over LiIon.
Higher energy density, they pack more energy per weight. Greater abundancy, cheaper to produce. Zinc air batts can be short circuited without detrimental effects (don't ever try this with LiIon!). Zinc air batts have built in filters which bind atmospheric CO2 during discharge. There are several options of recharging. The main ingredient zinc can be smeltered exclusively by solar thermal energy, and probably just as easily recycled the same way - do a search on SOLZINC.
As you can see, there are compelling reasons why zinc air is superior over lithium.

And yet the US hypes itself and the world on LiIon.
Indeed, a US based company which did excellent research on air zinc was sent broke a few years ago.
The major Lithium deposits are in the Andes (Chile/Argentina).
The chairman of A123 recently said at a meeting with President Bush:
"In the meantime, introducing the American public to the dramatic efficiency potential of the battery progress we have already made could kick start our national energy savings while providing invaluable experience and data for accelerating the essential transition from foreign oil to an ever cleaner electricity grid," Vieau noted.

Note the "transistion from foreign oil to an ever cleaner....."
And the lithium which'll necessarily have to come out of the Andes (there are only insignificant reserves on US soil)will not be called foreign lithium?

Someone please explain.

Anon said at August 25, 2007 4:29 PM:

Lithium is actually a very abundant element on earth. While there are certain limited preferred mineral deposits that are cheapest to use, my understanding is that the next best sources are not orders of magnitude more expensive in the long run to obtain lithium from. Dramatically higher usages of lithium that would be required by switching to either PHEVs or EV is likely to be constrained only in the long run by energy, labor, and capital equipment - sort of like Aluminum. However, in the short run (it takes 15 years or so to open up new mines), very quick widespread adoption of lithium batteries certainly seems problematic.

Nick said at August 29, 2007 2:09 PM:

"Do we know that lithium nanophosphate is non-linear the way some other batteries are in terms of deterioration?"

The effect seems to be much weaker, but it appears to still be there. Depth of Discharge of 80% gives about 2x as many cycles as DOD of 100%. GM is planning to limit DOD in the Volt to 70%, and maintain a narrow band of dischage level during vehicle operation, perhaps between 30% and 50% state of charge.

political forum said at August 30, 2007 4:29 PM:

I highly doubt that car batteries will have enough electricity to power a home. A better idea would be solar panels, then the home could power the car.


okashira said at August 31, 2007 11:41 PM:

Wrong. those "car batteries" will have more then enough power for a home. actually a 40-mile nanophosphate pack could power like 5-10 homes. Your car uses alot more power then a house.

typical power load is 2kw for a house. mabye 10-20kw if your really working some appliances. that's nothing for an EV battery pack. tesla pack can handle ~200kw.

Brian said at October 3, 2007 8:37 AM:

This is the cheapest form of energy that is only being applied in two ways. This technology is here now and very abundant. Used in conjunction with batteries, there would be an endless supply of cheap energy. For instance it could be used as a replacement for coal. Look here -->

Mark Bates said at October 11, 2007 10:44 AM:

Thought #1- I predict a lot of battery thefts for this new $10,000 batery, Why bother with the whole car? Just steat the battery ! The underground market for stolen $10,000 batteries with serial numbers filed off or faked and tracking devices removed will be roaring ! The dealers of these $10,000 batteries will have to be wary of the battery police !

Thought #2- By the time they get this $10,000 to market, will the average person make $10,000 a week ?

Thought #3- After this $10,000 batery up and running for a few years, will the cost drop to $500 ?

Thought #4- By the time they get this battery in the market, will I be too old to drive anyway so why should I care ?

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