April 28, 2008
A123Systems Pluggable Hybrid Conversion Kit For Prius

Worried about the coming energy crunch as world oil production starts declining? Here's one way to adapt to it: Spend $10,000 to upgrade a Prius to run 35-40 miles on a battery from A123 Systems.

Beginning this week, a company in the Boston area will be taking orders for what it says is the first mass-produced aftermarket conversion kit. The company, A123 Systems, is starting out with the Toyota Prius, with what it calls a range extender module. The module fits in the well normally occupied by the spare tire, with a charging port installed on the back bumper.

The A123 conversion will allow a Prius driver to substitute electricity, at about 3 cents a mile, for gasoline at three or four times that price.

In the United States electricity sells for an average of 10.64 cents/kwh (see the link for state level electricity costs). So a recharge would cost you about 55 cents (depending on the extent of heat losses). At 40 mpg and $4/gallon the Prius will cost you 10 cents a mile on gasoline.

The Hymotion conversion kit includes a 5000 watt-hours battery (as compared to the 300 watt-hours of the original Prius battery) that replaces the spare tire in a Prius. A123Systems is one of 2 front-runners to supply batteries for GM's forthcoming pluggable hybrid Chevy Volt which is also expected to do about 40 miles on battery.

Before you rush out to upgrade your Prius keep in mind that when using the standard electric motors in a Prius the top speed is either 35 mph or 42 mph (and can someone find an authoritative source on this?). I can't find anything on the A123 Systems web site for the Hymotion conversion kit that suggests they raise the speed limit with their conversion kit. So if you do a highway commute you probably aren't going to be able to cruise on only electric power. The coming pluggable hybrids such as the Chevy Volt probably won't suffer this limitation.

That 5000 watt-hour (or 5 kilowatt-hour) battery could push a pure electric big SUV about 10 miles. Getting that battery to push a Prius 4 times that far seems a bit of a stretch. Anyone have a good engineering reason to think under electric power a Prius would only use 125 watt-hours per mile? That seems low to me.

One of these conversion kits might make sense for a Prius used to travel many miles each day city driving. But the Prius's already high fuel efficiency makes it hard to earn back the cost of the upgrade. The battery takes 4 hours to charge up. If you travel 40 city miles to work every day (doing 40 mpg with gasoline power pre-conversion) and if you can charge up your car while in the office then you'll save 2 gallons a day. Well, that doesn't describe a whole lot of people. But if you could save 2 gallons a day then when gasoline goes to $5.50 per gallon you could save $10 per day (assuming $1 for the electricity to charge up twice a day) or $2500 per year.

Now, put the price of gasoline up to $11 per gallon and the pay-back period cuts in half. But if you wait to upgrade to a pluggable hybrid you'll get one once gasoline prices are much higher and battery prices much lower. Plus, cars designed from the start as pluggables will be cheaper and offer better performance than after-market upgrades. In other words, the economics of pluggables are going to improve a great deal in a few years time.

Share |      Randall Parker, 2008 April 28 07:33 PM  Energy Electric Cars

Wolf-Dog said at April 28, 2008 8:30 PM:

It turns out that there is an expensive lithium battery from Altairnano that costs at least 2 times as much as A123 Systems, but there is already an sports utility vehicle with ranger 130 miles, and in 2009 the range will be increased to 250 miles. This battery gets charged in 10 minutes, and it has a life that is at least 20 years even if it is charged every day.

The price of this car is over $47,500 including tax credits, and without tax subsidies it would probably be much more expensive. But overall, by 2020 there will almost certainly be cheap electric vehicles with range over 300 miles.



aa2 said at April 28, 2008 11:37 PM:

I'm already considering an electric vehicle for my next car. I maybe once a year travel more then 200 miles, and I could trade cars with someone in my family for a few days, if I was going long distance.

odograph said at April 29, 2008 4:56 AM:

It's weird, I think it is not worth it at all to a Prius owner ... but on the other hand a $25K + $10K electro-Prius is cooler than one of the $35K semi-luxury cars. Maybe the answer is that the $35K car buyer just downgrade to the base Prius and put $10K in their IRA.

On a purely technological basis, it's amazingly positive that A123 is confident of their product enough to do this ... and it's encouraging that prices might come down.

Anna said at April 29, 2008 9:50 AM:

At $10,000 for an A123 battery system and a per mile savings of 7 cents, that's about 143,000 miles to payback. I wonder how many miles the battery is good for? I am shocked that people are paying the premium for these hybrids that do not get better gas mileage than cars sold in America, such as the corolla and escort, that were built in the 90s. Not to mention that our tax system is subsidizing their cost. The only benefit I see is the long term benefit of supporting an industry that is committing R&D to shifting away from petroleum.

Wolf-Dog said at April 29, 2008 10:49 AM:

This web page from Phoenix Motorcars has a cost calculator form to compute the annual savings in terms of fuel.


In the future, when gasoline becomes $7 per gallon, and if the price of electricity remains approximately $0.10 per kwh, and if your work place is 50 miles away from your home (100 miles commute for 5 work days per week, meaning that you drive at least 25,000 miles per year), if you own a hybrid car with mileage 40 miles per gallon, and if you have paid $25,000 to buy this hybrid car, and if you spend $500 per year for repairs and maintenance, then after 6 years the extra cost of buying the more expensive $47,000 pure electric car from Phoenix Motorcars would have been amortized itself in comparison to the cheaper hybrid car that costs $25,000.

This is still with the more expensive AltairNanotech battery that costs 2 times more than the A123 battery.

Clearly the pure electric cars are the way to go, and in a few years as the price and performance of batteries become better, there is no question that oil will be replaced within 20 years. There is no question that within 20 years a pure electric car with 300 mile range will be sold under $20,000 (in today's dollars.)

Dan M said at April 29, 2008 1:11 PM:

Just thought I should point out a couple of things it seems you missed. One, the Volt is an electric car, with a means of recharging the battery on the fly (via diesel, gasoline, or fuel cell generators). There is absolutely no connections between the engine and the wheels. Think diesel electric railcars, or an EV1 with an onboard generator. Second, E-Flex is an architecture, and as such is planned as a replacement option for the drivetrain in your favourite car (ie, love the Camaro, sure wish there was an electric version available - you mean there IS?), or at least so the GM story goes.

The proof? GM is currently testing the drivetrain in an off the rental lot Malibu with the engine/transmission removed and E-Flex in it's place. Pretty revolutionary if you ask me.

Wolf-Dog said at April 29, 2008 1:28 PM:

It is true that Volt is recharged by means of a gasoline engine that is only connected to a generator, not to the transmission. But this still classifies Volt as a "hybrid" car, even though it is simplified considerably. In any case, this is not a "real" pure electric car. A real electric car will be much simpler. As another commentator said, the automobile companies (at least in the US) are behaving like a front to protect the oil company profits. They will resist pure electric cars until the end of time. Also pure electric cars are simply too durable and too simple for automobile companies to make long term profits. A pure electric car would last 50 years or more without counting the battery, the tires and the cheap electric motors that are to be replaced, and there are carbirators, radiators, exhaust pipes, starter motors, etc, and this is deleterious to the profits of big automobile companies and also to the part makers that work with the automobile companies, not to mention the service garages, etc. If you count the part manufacturers and the service garages, more than a million jobs might be lost if the US switches to electric cars. Additionally, millions of jobs connected with the oil industry will be lost. This is why there will be resistance against pure electric cars, and a lot of lobbying will happen against electric cars.

Randall Parker said at April 29, 2008 5:56 PM:


Yes, at current oil prices it is hard to justify $10000 to reduce your gasoline bill if you are already driving a car as fuel efficient as a Prius.

Also, yes, it says a lot about the confidence of A123Systems in their battery.

But oil production will eventually drop far enough and prices rise that $10000 for a pluggable hybrid upgrade will become cost justifiable for some drivers.

How far and fast will battery prices drop? I wish I knew.

aa2 said at April 29, 2008 11:05 PM:

I'd like to see some calculations for Europe too. I understand in the UK a gallon of gas is over 9.50$ USD. If someone has a long commute that altair nano phoenix car for 2009, would seem to be a big hit coming.

Wolf-Dog said at April 30, 2008 1:37 PM:

If a gallon gasoline in UK is already $9.50 USD, then within a decade all over EU it will almost certainly be $20 per gallon. By then the electric cars will be far more affordable also.

So far, the Phoenix Motocars SUV which costs over $47,000 has a range of 130 miles per charge, but the 250 mile range version in 2009 will almost certainly cost a lot more.

Apparently, there will also be a rival electric SUV with 350 mile range, also using the AltairNano battery in the year 2010, but the price will be a prohibitive $60,000, and ordinary citizens cannot afford it even if they are commuting long distances. So far these advanced nano batteries are still hand-made in local factories in California, and they are not mass produced because the infrastructure for such high precision manufacturing is not yet perfected.


But the overall problem is this: the oil companies have intentionally fluctuated the price of oil for more than half a century since WW II, and usually every spike in the price of oil was followed by a moderate pullback, keeping the would-be and wannabe electric car manufacturers and battery inventors insecure and confused.. This insecurity and uncertainty always made people uncomfortable, and there was always the threat that the charging of the batteries will be difficult due to lack of cables in the streets, etc, even if the batteries are invented and manufactured. It turns out that the cables in every street corner can be installed with less than half the war money spent.

Randall Parker said at April 30, 2008 6:27 PM:

On calculations: Imagine someone is so unfortunate that they drive 15,000 miles per year. Suppose they get 30 miles per gallon. They will use 500 gallons per year. Okay, then think about how much they'd spend on gasoline per year at different gas prices:

$5/gallon: $2500
$10/gallon: $5000
$15/gallon: $7500
$20/gallon: $10000

At first glance there's a liquid fuel price at which expensive big electric batteries for cars become justifiable.

But while high mileage drivers might seem the natural first users of electric cars they hit up against a big problem: range. Longer distances driven per year correlate with longer distances per trip. Rather quickly a driver runs up against battery range limitations. How many of those 15,000 miles are driven on trips that are longer than a single battery charge's range?

We need cheaper, lighter weight, and higher capacity batteries for the higher mileage drivers.

Paul F. Dietz said at May 1, 2008 5:42 AM:

Oof the risks of buying a non-plug-in hybrid is that gas prices may escalate further, costing you money. The risk of buying a plug-in is that prices may fall, wasting the investment.

With the upgrade kit, you can delay part of the capital expenditure until you have more information (did prices rise or fall?). Since you will be making decisions with more complete information, your outcome will be closer to optimal. You can also buy the batteries later when they are likely to be less expensive.

I hope every hybrid maker is at least thinking about making this sort of extensibility a part of their designs.

aa2 said at May 3, 2008 1:05 AM:

Randall said, "We need cheaper, lighter weight, and higher capacity batteries for the higher mileage drivers."

Thats the main point it seems. Right now batteries are getting close to being viable, but it still is stretching it. Cut the cost/performance by 50% or 75% over time and at some point its going to make perfect sense. In Europe with oil at like 8 dollars a gallon its going to make sense even faster there.

Think about this, whether we get the beneficial price comparison between plug-ins and oil in 5 years, or 10 years, or 15 years.. in the grand scheme of things that isn't much difference. Say plug-ins don't dominate until 2023, that still means most of the 21st century driving is going to be powered by electricity.

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