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A123Systems Launches Hymotion PHEV Conversion Module for Prius

EPA Urban Dynamometer Driving Schedule (UDDS) test results for an L5-equipped Prius. The heavy gray lines show when the engine is in operation. Click to enlarge.

A123Systems has fully launched the Hymotion L5 plug-in hybrid module designed to convert a Toyota Prius, model years 2004 – 2008, into a plug-in hybrid capable of achieving up to 100 mpg for 30-40 miles within the electrically assisted driving range. A123Systems acquired Hymotion in February 2007. (Earlier post.)

The 5 kWh L5 Plug-in Conversion Module (PCM) is priced at $9,995, which includes a three-year standard warranty and installation. Currently, Hymotion is only conducting L5 installations in the United States through Certified Hymotion Installation Partners (Green CHIP dealers). Canadian vehicles can be brought to US installation locations.

The A123Systems Hymotion L5 Plug-in Conversion Module (PCM) for the Prius. Click to enlarge.

A123Systems is currently establishing and certifying its CHIP dealer network in cities around the country. Initial Green CHIP dealers will be located in Boston, Washington, DC, Minneapolis, Seattle, San Francisco and Los Angeles.

In April 2008, in the absence of established PHEV certification procedures, the California Air Resources Board (ARB) outlined a path for conditional approval for A123Systems to sell up to 500 L5 PCMs in California as a means of initiating the rollout. The company is now in the process of finalizing that approval.

A123Systems and others are working with ARB to establish full certification procedures for PHEVs. Once those procedures are final, there would be no restriction on quantities sold (assuming the L5 meets certification).

The L5 module fits in the spare wheel well of the Prius, preserving trunk space.


The 2004-8 Prius can only do about 30 MPH in EV mode, something of a limitation. But the next generation, able to do 60+ MPH in EV mode will be ideal for the Hymotion conversion. Say the Prius costs $27,000 with all the bells and whistles, and the kit costs another $10,000. So , for about $37,000 you can be the first on your block to drive a PHEV and seldom pay the skyrocketing gasoline price.


Higher gas prices and the branding of PHEVs as environmental status symbols will be important to boost sales of this product. Hopefully A123 will do several thousands of these conversions on existing and new Priuses until Toyota launch their own PHEV and even then they can still do the conversions of the older models. These conversions will provide valuable additional durability tests of their battery and it will help a little to scale up production of batteries. It will also importantly help to brand A123 as a leading manufacturer of auto grade batteries.

A123 even did a full scale crash test certification of their product. There is a video on their web that looks quite convincing to me at least. The battery certainly doesn’t explode although it looks as if it is completely smashed.


I read about the AQMD certification for natural gas conversions. They talk about cleaner air and using cleaner fuels, but they charge more than $50,000 per car kit that you want to certify. That is $250,000 for 5 of the most popular cars and trucks that you would like to convert. We can do better than this.


I want one for my Camry. I don't care if the costs don't make a huge amount of sense. Most of my driving is in town at less than 50kph. What I would like to see though is an EV only switch with it.


from the pictures, it looks like 8 battery modules, perhaps each one holding 90 cells of the small 2.3Ah A123 batteries.. that would work out to about 5kwh and about 112lbs in batteries. How much does a spare tire weigh?.. Price is reasonable, it is about $2500 in batteries alone, assuming they got them at rock bottom wholesale.

It may be cheaper if they use their larger cells, but I have no data on that.


They need more dealers, in Florida or the SE at least..


The only sense to buy the conversion is to buy used Prius (the older the better price) and do the conversion.
The lowest price that I found for used Prius around NYC is $16 000. Now you will add the $10000= $26000. That still pretty steep.

Set see some cost analysis:
Let say that Prius make 50mpg (bit stretching) that 2000 gallons per 100000 miles with let say $4 per gallon; 2000x$4= $8000.
Pure electric: 5KW per 40miles that 12.5KW per 100miles or 12500KW per 100000miles. The cost for 1KW in NYC in summer is ~$0.22. The energy cost ; 12500KWx$0.22=$2750
Used Prius with conversion: $16000+$10000+$2700 =$28700
For new Prius with conversion: $27000+$10000+$2700=$39700
New Prius with out conversion: $28000+$8000=$36000

The problem is that to the electric power from the grid you need to add another $2000- $4000 for delivery fees that they charge.
So :
Used Prius with conversion: $16000+$10000+$2700+ $3000=$31700
For new Prius with conversion: $27000+$10000+$2700+$3000=$42700

What the conclusion?
Well.. buy used Prius, buy the conversion ...and ... buy or build 1KW wind generator for around $2000- $5000 and charge the Prius for free.

Yes that could be good idea to sell the conversion kit with small vertical wind turbine (vertical to prevent the noise in the city). You will install it in you home and connect the Prius over night.
Now we toking about energy independence.

How about that.


From what I have heard, urban wind turbines need to be fairly high up to get any meaningful output. Solar panels might be a good idea. If the prices really do come down in the next few years that could be possible. I like the idea of creating a 10' x 20' solar car port. 200 square feet could produce almost 3000 watts peak power and might be able to power your car for 40 miles or so.

That not exactly true that you need to locate the wind turbine really high in the city. In city in between building the wind, in many cases, getting really strong (that specially true in Manhattan).

Yes the solar option is definitely attractive. The only problem is the cost ($3000/KW) and limited time of exposure (around 6 hours).

It almost impassible to build by your self solar pane. Wind turbine can be build by any one with very little cost.

The wind turbine option is available right now considering the cost and availability.
The energy urgency is so high right now that we need resolution with in 2-5 years not 10-50 years.

I believe that solar energy with in 2 year become very accessible for every one .

The rick with using the A123 battery is that the can deliver very high power in very short time. The power is need to generate enormous torque by the electric motor to get the acceleration.
It is enough power for the car to start from 0mph to nominal speed with out turning on the engine. That mean the conversion kit will work perfect in series hybrid. Just swap the original engine with 10-20KW gen set and you are home.


I think wind has its place, but that seems to be in large wind turbine installations where the wind blows with regularity. If you study the small wind machines, you will see that the ratings are pretty unrealistic. Most of the areas where people want to put them produce no where near their rated capacity.

I have seen lots of sites where people are building their own. One site is devoted to PMAs (Permanent Magnet Alternators) that have very good output. But on an annual basis, solar PV is calculated on 2000 sun hours per year. There are not many wind installation sites that can say the same with outputs anywhere near their rated peak capacity.


I guess you have to pay to be on the leading edge, just like with all new technologies. In this case, the feeling that you really contribute to the sustainability of this planet may be priceless.


I guess you have to pay to be on the leading edge, just like with all new technologies. In this case, the feeling that you really contribute to the sustainability of this planet may be priceless.


What about the Ford Escape?
What can they do for something that
is comfy to drag the kids and wife in.

The price is stiff but with gas going to $4
a gallon quickly maybe it can be justified. It
seems the oil barrons figured out that we will
pay huge sums for oil.


dont forget all the chicks that will flock to you :)

If we have any gas shortages, that conversion will suddenly become very attractive.. and hopefully the price will come down.

Just a little on cost. For about 10,000 you double your mileage. So lets assume you own a Prius that gets 45 MPG.
And you drive 15,000 miles a year. So you burn 333 gallons at say $3.75 the first year, $4.25 the second year, and $4.75 the third year. So your fuel cost over three years is about $4,250. And you cut that in half, saving $2,125.
But you need to buy "equivalent gallons (EQ)" of electricity at about $1.00 per EQ. So you spend an additional $500 for the juice, reducing your savings to $1,625 over three years. But lets run the numbers assuming skyrocketing fuel costs. Let's say gas goes to $4.00 the first year, $6.00 the second year, and $8.00 the third year. So you spend $6,000 on gas over three years, or with the kit $3,500 for a savings of $2,500.

Still does not make economic sense. But if a gas shortage occurs where you cannot get gas, no matter the price, it is sweet. And you will not be polluting the air as much.


They will probably have packs for the Escape hybrid. You can get a 2005 for about $15,000 these days. 30 mph is not bad to be able to haul all the kids and their stuff.


A123 offers this plug-in calculator. It is probably much more accurate than any back of the envelope calculation.


I ran a typical commute scenario on the A123 calculator: it works out that at about $1100/year savings in gas ($4.00/gal) it will be 10 years before the Hymotion investment turns positive. Then again you are investing in a cleaner, greener energy future. And the number of trips to the gas station dropped from 45, (Prius) to 20 annually.



There should also be a decrease in maintenance costs since a PHEV is running in electrical mode a greater percentage of the time than a HEV or ICE and electrical components and systems should require less maintenance than mechanical ones.


Something is fishy with their graph. They claim to get 66 mpg when the battery is depleted. The prius gets 45-50 mpg on the highway, how could you get 66 in the Hymotion, once the battery is used up?

Seems like a money loser to invest $10,000 + higher electric bills to save $4000 over 10 years.

PHEV is still a research project.


Life would be great if we had honest lawmakers in office who did not owe appointments to special interest groups. They would enact laws that require big oil to hand over a portion of profits from the pumps. The money could be used to lower the price on products like
this one.


The odd part about subsidies is things tend to stay subsidized. If you invest in R&D to reduce the costs of the product, you might get further. People like Nanosolar and others should be able to get funds to do the R&D and advance the state of the art. Instead they have to go begging to Venture Capitalists promising the moon for enough money to go broke...what a country.


@ Jerry

Uh that would be called communism or at the least socialism. I wouldn't think that would make life 'great'.

@ Realist: "Something is fishy with their graph. They claim to get 66 mpg when the battery is depleted. The prius gets 45-50 mpg on the highway, how could you get 66 in the Hymotion, once the battery is used up?"

It could be that the drive cycle that Hymotion used is on the slow side, more city driving than highway. On more than one occasion, I've gotten my own Prius close to 70 MPG over ten minutes of city driving.

Here's another possibility. Does the Hymotion conversion kit also increase the amount of energy recaptured from regenerative braking? I seem to remember reading that the charge rate of the standard Prius NiMH batteries is not sufficient to accept all the energy which could be recaptured from a full stop from highway speeds.

Hi fishy, I seem to be reading the graph differently than you. Over the driving cycle depicted on the graph, the stock Prius burned about 5.6 gallons of fuel, whereas the modified Prius burned over the same cycle 3.4 gallons. This would work out to about 72 MPG for the Hymotion Prius, about 60% better than the stock (45 MPG) Prius.

The graph does not show the battery being used up (SOC zero)it shows the battery being used up (charge depleting mode) until the ICE is starts maintaining the battery SOC, the flat green line.

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