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A123Systems to Market PHEV Conversion Packs in 2008

1 May 2007

Lithium-ion battery manufacturer A123Systems intends to begin marketing battery packs in 2008 for third-party conversion of hybrids to plug-in hybrid electric vehicles (PHEVs), according to A123Systems CEO David Vieau. Vieau made the remarks in testimony before the US Senate Committee On Finance Subcommittee On Energy, Natural Resources, And Infrastructure.

A123Systems has been working closely with Hymotion on the plug-in conversion systems. Recently, the California South Coast Air Quality Management District (AQMD) awarded the companies a contract to convert 10 Prius hybrids to PHEVs. (Earlier post.)

The Hymotion PHEV module requires minimal modification to the stock vehicle. All necessary components and safety features are integrated and contained within the module, including: batteries, power electronics, crash sensors, power electronics, charger, battery management system, safety sensors and manual-electric interlock. The system does not require removal of the OEM battery pack and can be installed in less than 2 hours, according to the companies.

After focusing on fleet testing this year, A123systems intends to market the PHEV conversion modules starting in 2008.

It will be certified to meet all applicable new car test standards and will be installed by trained mechanics in less than 2 hours, without any changes to the underlying electronics, mechanics or materially useable space of the production hybrid other than the installation of the plug in the rear bumper.

The applicable market in the US for standard production hybrids will be approaching 1 million through the course of this year. With almost two dozen hybrid models expected by the end of 2008, there will be 5 million standard hybrids on the road by 2010. At an initial 40 mile module installed price of $10,000 supported with a $3,500 tax credit, the payback period for a fleet owner with $3.00/gallon gas is 2.5 years, against an expected life of 10 or more years. The payback period for the average commuter driving 11,000 miles per year would be 5.5 years. These calculations place no value on the net reduction of approximately 100 tons of carbon dioxide and other emissions over the life of the vehicle and take no account of the cost reductions which could accrue from additional materials research and increasing production volumes.

—David Vieau

Vieau urged the senators to apply any tax incentive applicable to customers of factory original plug-in hybrids some years out to tested, standardized plug-in modules offered earlier by qualified companies.

We estimate a fivefold increase in demand for these modules from an increasingly responsive American public as a result of providing for this early responder tax credit.

—David Vieau

The current Hymotion/A123Systems PHEV module is a 5 kWh pack that operates only in the all-electric mode of the conventional Prius—i.e., maximum charge-depletion mode. (As a contrast, the Energy CS Prius—which replaces the OEM pack—has two modes of operation: EV mode and a blended mode designed to deliver better emissions performance.)

A Hymotion PHEV was one of several plug-ins already tested by Argonne National Laboratory to assess fuel economy, energy consumption and emissions. Among their conclusions, the researchers found that NOx and THC emissions from both the Hymotion and Energy CS packs exceeded those of the production Prius in city cycle testing. (Earlier post.)

The issue is currently faced by all the PHEV conversions. The production Prius loads the engine and warms the catalyst during cold-start operations to meet SULEV emissions standards.

With the maximum charge-depletion operation of the Hymotion Prius, the engine is used when a speed or power threshold is reached. If the power required form the engine is large before the catalyst is warmed up, the emissions may be impacted significantly.

—“Testing and Analysis of Three Plug-in Hybrid Electric Vehicles”

Argonne test results found that while NOx and THC emissions for the production Prius and the PHEV Prius were similar on the first test cycle, subsequent cycles had higher emissions levels for the PHEV since the engine temperature and catalyst temperature were not at the proper operating level.

In consecutive city cycle testing, Argonne found that fuel economy for the PHEV ranged from 148 mpg, up to 200 mpg, and down to 66.4 mpg as the battery depleted. Highway cycle results yielded fuel economy ranging from 112 mpg down to 62.4 mpg.

Calculated Energy Results for Hymotion PHEV Prius for UDDS Cycle
Factor Value
Charge depletion distance [mi] 29.9
UF Weighted Fuel Economy [mpg] 94.6
UF Weighted Electric Usage [DC Wh/mi] 58.4
Petroleum Displacement Factor 0.474
PHEV Equivalent range [mi] 14.2

The Argonne researchers also use a Utility Factor weighted analysis to calculate composite fuel economy and energy usage. A petroleum displacement factor (PDF) characterizes how aggressively electrical energy used in charge-depletion mode displaces petroleum as compared to the charge-sustaining operation of the vehicle. The PHEV-equivalent mileage is the calculated range of the vehicle if it were to operate purely as a full electric vehicle. (See table at right.)

Based on this initial testing project, the Argonne team concluded that there are three primary areas of research required “to create a successful PHEV”:

  • The trade-off of battery cost to petroleum displacement.

  • Emissions control strategies in charge-depletion operation to maximize petroleum displacement while emissions during cold starts and the many engine restart conditions.

  • The impact of reduced engine efficiency due to operation under reduced load during charge-depletion mode.


  • David Vieau Testimony

  • Testing and Analysis of Three Plug-in Hybrid Electric Vehicles (SAE 2007-01-0283)

May 1, 2007 in Plug-ins | Permalink | Comments (50) | TrackBack (0)


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I hope the automakers are paying attention to this. We could be in for a quantum leap in fuel efficiency... with any luck the costs will drop like a rock, too.

Wouldn't a glow plug in the exhaust system help solve the emissions issue? It could come on when the battery hits a certain state of charge so that the catalytic converter is warm enough.

Only if they can solve the emissions issue.

Otherwise this'll get about as far as diesels.....


The first gen North American Prius had an HC trap that would operate when the cat was below it's operating temperature, then once it was warmed, flow of the trapped unburned fuel would be directed back into the cat to be burned off. The second gen Prius uses a thermos of hot coolant to help minimize cold-start emissions, probably a cheaper option, but I suspect in terms of PHEV you'd be better off with the trap system as well. I don't see too much of a problem with the extra emissions associated with the PHEV conversions since we're talking about taking an extremely clean car and making it a very clean car, still less pollution than many other new 'clean' cars and trucks being sold today, although I'm sure regulatory issues are the main hurdle.

I think the emissions problem is mainly in the context of aftermarket retrofits for plug-in. Designed from the ground up there are probably numerous ways of solving the problem. The aftermarket products, however, have limits on how much tinkering they can do with the installed emissions hardware and the underlying engine control technology. Undoubtedly, when Toyota releases the plug version of Prius it will have a very effective and elegant solution.

The manufacturers claim a payback period of 5.5 years for the average consumer. Can anyonde demonstrate how this payback period was computed. From the numbers in the table, assuming they apply to this pack, I don't see how you get payback that quickly.

I am thinking along the lines of another commentor as far as helping with cold start emissions. i find that i waste a lot of regen braking energy as the battery can't utilize it due to various factors. Couldn't some of that energy be redirected to heat the exhaust system/engine to mitigate some of the cold start emission problems for a PHEV? It seems that it would also take more load off the braking system if the motor were engaged and applying that energy to good use.

Years and years ago, Ford had an experimental electrically-preheated catalytic converter.  It had a terminal for a cable the size of the starter cable.  I can see some issues with trying to build a heater into a ceramic matrix, but a PHEV should have no shortage of battery power to pre-warm the cat before starting the engine.

I think I'd find it easier to "pre-heat" the engine oil or coolant than a catalytic convertor. Might still leave the cat in a less efficient state but it keeps the engine from running in the warm-up "open loop" state where a/f ratios tend to be richer.

So, the CEO for a company that enthusiasts had hoped could make a difference is now parroting the party* line

* (Chevron/Texaco/Cobasys-GM-A123Systems/MIT)

Use the batteries in HEVs. Stick to the ICE paradigm. Some day fuel cells will make a difference.

Meanwhile, XOM profits went up another ten dollars per second.

jcwinnie, We'll all be very excited if you want to start a company making highway capable pure electric cars that don't cost more than the "ICE paradigm." But I think if you try you'll find the doing is a lot harder than the complaining that others are not doing it.

jcwinnie has a good point. When battery is still scarce and very expensive ($10,000 for a 5kwh pack!), one should use these batteries to make as many HEV's as possible, with smaller 1.3kwh packs like in the Prius II. The environmental impact and petroleum saved from having 5 HEV's (having 1.3kwh battery each) will far outweigh those of a single PHEV having a 1.3 kwh factory NiMh pack PLUS one 5kwh A123 Li-ion pack.

It's not until over 50% of all cars are HEV's and still leaving a surplus of low-cost nanotech Lithium batteries that we should consider making PHEV's.

Hybrid sales of Toyota and Honda has hit 24,593 in Apr-2007.

Civic - 2,855
Accord - 318
Insight - 2
Total 3,175

Prius - 13,056
Camry - 4,410
Highlander - 2,394

RX400h - 1,384
GS450h - 174
Total - 21,418

Last year, it was 21,707. This alone is 13 % increase. Still Ford & Nissan has to report.

Meanwhile all vehicle sales put together is down 2.6 %

Any word on a kit for the Camry hybrid?

Any word on a kit for the Camry hybrid?

Patrick:  cars run "open loop" only when the oxygen sensor is too cold to operate.  If you can preheat the O2 sensor as well as the catalyst to operating temperature, you can go closed-loop from the first few seconds of operation.


I think A123 wants all the sales they can get. They are in need of more markets. They are wanting to ramp production. No high production HEV uses Li, they use NiMH. You can eat cake in your PHEV and have it in your HEV as well.

If it were a materials shortage your argument might be valid, but right now the more demand the more economies of scale, the more competition and the cheaper the batteries will be.

Battery packs demand effective cooling. Seems easy enough to reject heat to the engine and catalyst. I recall a previous post here about a "float loop" battery cooling cycle that would fit the bill.


All modern oxygen sensors have electric pre-heating, and come on line in about 5 seconds. Still, initial overrich of mixture to get cool engine started and cold cat produce a lot of HC. The best solution is to beef-up traction electric motor to avoid start-up of ICE even if you floor the pedal. Current generation Prius with only 30 KW max electric power can not do this.


go to autobloggreen and listen to the interview with Dr Alan Gotcher of Altair/Phoenix.

The local papers are forecasting $2 Can/L in many places in Canada and $4 USD/gal in USA this summer. This would make pay back time much shorter yet.

Let me try this again. Does anyone know how they computed payback time. Even if you assume zero electricity costs and zero gas costs, for that matter, this doesn't seem to compute.

A series phev-40 with a biodiesel (from algae) range extender build from the ground up seems to be the best solution. The speed of innovation is astounding!

I can't get anywhere near the 5.5 yr payback. If the average Prius is getting 45 mpg, then the car consumes 244 gallons/yr under the 11,000 mi/yr example. If plugin reduced gasoline consumption to 0 and electricity were free, then the buyer would avoid 5.5 yrs * 244 gal/yr * $3/gal, or $4033 over the period. Nowhere near the $6500, and that's with ridiculous assumptions.

Also, a 40-mile pack would require 8-10 kWh, not 5 kWh, unless it is 50% blended power (which surprisingly, this design apparently does not permit).

Perhaps they are also counting lower servicing costs in their calculations (due to reduced engine/break wear)?

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