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EnergyCS Delivers First Commercial Plug-In Prius in US; UK to Follow

EnergyCS has delivered the first Toyota Prius sedan retrofitted with plug-in hybrid technology to California’s South Coast Air Quality Management District (AQMD) for testing and evaluation. EnergyCS and Clean-Tech formed a joint venture—EDrive—in 2005 to manufacture and market the retrofit, which will initially be installed and serviced by Clean-Tech.

This vehicle is the first of eight demonstration vehicles ordered as part of contracts between EnergyCS and the South Coast AQMD as well as other electric utility partners. In early testing, the vehicles have averaged over 100 MPG by combining grid electricity with the existing hybrid technology.

Using a normal house outlet, a nightly re-charge of about $1 worth of electricity cuts the Toyota Prius gasoline consumption in half for over 50 miles the following day.

After the additional electricity has been spent, the vehicles perform like a standard Prius until plugged in again. The South Coast AQMD issued a contract for up to six of the demonstration vehicles in September.

The PHEV systems, which will be commercialized under the EDrive brand name, have been in open development since April of 2005. (Earlier post.)

EnergyCS is proud to be leading this program with AQMD and our other project partners. Our demonstration prototypes for this program and our other early adopters will provide valuable data for plug-in hybrid passenger vehicles in real world driving conditions. This is an exciting project and we’ve come a long way since last year!

—Pete Nortman, president of EnergyCS

The EnergyCS plug-in Prius uses Valence Lithium-ion batteries to provide approximately 9kWh of storage and thus the extended all-electric driving range. EDrive hopes to begin taking orders from consumers for the systems soon.

The delivery of the demonstration vehicles is a significant step towards a commercial version of the system. Before a PHEV retrofit can be marketed to the public, it’s roadworthiness and durability has to be proven. It’s not just about throwing a few extra batteries into the back of a Prius.

—Greg Hanssen, President of EDrive

The system, which works with the second-generation Prius, is expected to retail for under $12,000 when full production is reached. (That is in addition to the cost of the Prius.) Once the Toyota Prius systems begin commercial delivery, EnergyCS plans to develop additional plug in platforms and work with project partners to develop new technologies revolving around its core competencies in batteries, electronics, vehicle and HVDC power system integration.

EnergyCS is also partnering with Amberjac in the UK to launch the PHEV retrofit kits. (Earlier post.) Amberjac is also delivering a commercial release of its retrofitted plug-in Prius models this year. Amberjac is working with UK-based GoinGreen, a retailer of electric cars, which has announced availability of the retrofitted plug-in starting this month.



It is non-sense to talk about MPG for the Plug-in hybrid.
For the Plug-in hybrid, the fuel consumption test needs to be by two different ways. The one is using Gas and Electric but the battery charge state has to be same before and after the test. It is same as the current EPA test for the hybrid vehicle such as Toyota Prius. The other is using Electric only and the result is by MPKWH (mile/KWH). And when we know the cost of Gas and Electric, we can calculate MP$(mile/$).
For example, Gas: 50 mile/gallon, 20 mile/$ (@ 2.5$/gallon) Electric: 5.0 mile/KWH, 50 mile/$ (@ 0.1$/KWH)
Now we can compare the value. Of course MPKWH is more important than MPG for Plug-in hybrid.

Gunnar Heinrich

That's wonderful news - $1 for evening's recharge plus the gas savings.

I had heard that there were Prius tuners out there and that at first Toyota Motors were dismissing these tuners' green improvements and add ons to the original Prius design. But since that time, the Japanese automaker has now embraced this Prius tuner culture.

With good effect, I'm sure.


Can the battery be charged at a level beyond which it is charged currently. Or, is the only additional charging from an electrical outlet. This would affect the gas mileage. For example, when I am going downhill in my Prius, additional charging could take place if my stock battery had greater capacity.



yes, you could choose to charge your batts to just 90% so that you can let the car charge the batts the rest of the way while driving down a big hill, but it'd only save you about .9kWhrs (less than 10 cents of electricity, depending on your rate. less that 2 cents in some parts of Washington State)

$12,000 sounds like abusive pricing. I wonder how much toyota would have to charge to add a cord and a bigger battery?


Shaun -- Actually, I could save on gas,too. Once the juice from the outlet charge was exhausted, the recharge from going downhill would be greater than with the stock Prius. I drive some really big hills here in Colorado and my Prius recharges fully about half way down the hill. Thus, the benefit of the downward slope is being wasted. Regardless, even without the plug in feature, it seems like a bigger battery for my kind of driving would increase my gas mileage.

Of course, the extra mileage has to be weighed against the extra cost.

Bud Johns

Guys, I too have a Prius, and you would not be able to store more energy going downhill with more battery capacity. Yes, mine goes double green too, but in reality Toyota made it where you can never overcharge the battery. You can if you tow the car and it's not on and "neutral" selected, it might even catch fire! In any case, the batt will be ruined after a short number of miles. On another note, my guess is the next generation Prius will be a plug in, as battery technology marches forward and prices make it possible. Plus, it would be MUCH cheaper for Toyota to do it than aftermarket people, especially in a couple more years when the next gen Prius comes out.


bud johns, if i understand correctly, energyCS makes adjustments to the toyota software to let it know that there's a bigger battery in the car. they change the battery you know.

Bud Johns

Hey, lensovet, I realize you can always change software, but I wasn't talking about that. Please carefully read what I said, I know this car VERY well. Actually better than most people not named Einstien.


Ok, lets do the math.
Regular Prius = 50 MPG, the PHEV version = 100 MPG. Daily commute = 50 miles.
Cost per gallon of gas = $3.00 (US)
PHEV mod = $10000 (US)
Over 50 miles you will use 0.5 gallons of gasoline
cost =$1.50
Battery recharge cost = $1.00
Total cost of commute = $2.50
Saving = $0.50

Pay back time would then equal (10000/0.5)*50 = 1,000,000 miles

Uh, yeah. This makes sense really it does.

Rafael Seidl

I'm with Cosmo on this one. Extending battery-only range does not make economic sense once you factor in amortization costs. Even If Toyota could deliver a comparable system for a $6000 markup, it still would not make any sense.

A more sensible approach is to focus instead on really efficient recuperative braking. That means:

(a) engine should be decoupled from gear box during deceleration (requires a single or dual clutch, whose operation may be automated)

(b) all four wheels should contribute (requires electric motor-generators on both axles, preferably permanent-magnet types)

(c) power electronics should be very efficient (may require forced cooling)

(d) power inrush should be buffered in electric double-layer capacitors aka ultracapacitors (no chemical reactions involved)

Alternative designs based on hydraulic or pneumatic storage are the subject of separate research.

The high torque levels required for efficient braking are also available during acceleration. Therefore, such a system can be paired with a small three-cylinder turbocharged spark ignition engine with 2nd generation direct fuel injection.

hampden wireless

If Toyota made a plug in from the factory almost half of the electronics of the energycs system would not be needed. Alot of work is used to 'fool' the Prius into using the extra energy from the larger batteries.

The biggest changes if the plug in came from the factory would be software, the bigger batteries which would only cost about $1500 and a battery charging system which at most could be made for $500. Now I am not saying Toyota would sell this for $2000, I am sure they would mark it up.

I would want this option if it was less then $4000 even if it never paid back. I would have to go to the gas station less and I would have a 75% electric car.


The reason it is $12,000 is because they are using Valence Lithium-ion batteries which from what I have read are by far the best Lithium ion out there. I don't think anyone is even close. They are safe from thermal run-away which is a major concern if you got in a accident because they use a phosphate base. You don't want burning battery acid every where.

Len Wallace

say---does anyone know if the 05 prius battery is the same as the 02???? I have an 02 that keeps giving me a "problem" and it regards battery charge level. I have a wrecked 05 Prius that I could snatch the battery from if it's a perfect fit.


also we have to remember... now the electric motors are working harder.. will they overheat? or the life expectancy will be shortened... and the cost of the electric motors....


Len - The 02 Prius uses a bigger, higher voltage battery than the 05. It may be possible to put an 02 battery into an 05 by removing some banks of cells, but not the other way around.

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