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Plug-In Supply Inc. Introduces Lead-Acid PHEV Prius Conversion System for $4,995

Plug-In Supply, Inc unveiled its PbA10 Conversion System last week at the Plug-in 2008 conference in San Jose. The PbA10 Conversion System, based on the CalCars Open Source design, turns a standard 2004-2008 model year Prius into a Plug-in Hybrid Electric Vehicle (PHEV) with an all-electric range of 10-15 miles and improved average mileage of up to 100 miles per gallon (plus 1 cent/mile of electricity).

The conversion system uses a 5 kWh pack comprising new extended life lead-acid batteries (more than 800 cycles) for better battery longevity than was previously available.  The system is designed to permit an upgrade to lithium iron phosphate batteries with an all electric range of 15-20 miles as costs for these longer range batteries decline.

The PbA PHEV Assembly is a complete, tested, and ready to install pack. It provides access to the spare tire and contains 20 PbA20-12 lead-acid batteries, plus all high voltage components and control electronics in a strong welded steel enclosure. Expected battery life for the PbA system is about 2 years. The weight of the PbA system is 360 lb (163 kg), compared to 150 lb (68 kg) for the lithium-ion system.

Maximum speed in all-electric mode is 52 mph.

Plug-in Supply is currently working on a PSI Lithium Ion Phosphate Prius+ conversion, featuring the latest batteries from Phoenix Silicon International (PSI). The chassis will provide access to the spare tire and is expected to provide 16 miles of EV mode operation and last the life of the car.

Converting the Prius to a plug-in has been a popular topic since Ron Gremban, CalCars Technical Lead, was the first to convert his Prius in 2004.  Since then, about two hundred cars have been converted in what was formerly a slow and complicated process.

By refining the design for manufacturing, Plug-In Supply’s Conversion System reduced the conversion time from several weeks to just one day in 2007.  Further improvements in design have reduced the cost and complexity while improving reliability and battery longevity.

Plug-In Supply Inc. is a Petaluma, California-based supplier of Conversion Systems and components serving the Hybrid Electric Vehicle (HEV) and Plug-in Hybrid Electric Vehicle (PHEV) aftermarket. Plug-In Supply Inc. is operated by Robb Protheroe, an engineer and long time proponent of electrically powered vehicles.



Battery range is 15 miles max. The cycle life is 800. 800 x 15 equals 12,000 miles. The cost is $5,000. $5,000/12,000 miles is 41.6 cents per mile just for the battery depreciation.

The batteries weigh 360 pounds. 360 pounds of lead acid batteries at costco costs $450. They may not have a cycle life of 800, but you could sure replace them several times for $5,000.

The article states the expected battery life is 2 years. Am I supposed to get 800 cycles in two years?

These are the reasons why GM killed the electric car.

Battery technology is not there yet. The hybrid is over-rated. Even at today's elevated prices it is more economical to get a corolla and buy fuel with the savings. This could change in the future, because of more expensive gasoline or cheaper more durable batteries, but I think it is just as likely we could come up with a nice source of liquid fuels from biomass. Liquid fuels are great!



JRod: Sure liquid fuels are wonderful. But you'll never power your entire fleet from biomass. Battery technology has been improving over the last number of years at a surprising rate. Their last major hurdle is cost and even that looks to improve.

Hybrids are not overrated. Take Honda's new insight, coming out next year. $1500 cost for the hybrid system. That will take only 40k miles to make up, plus the car would be worth more at that point.

Heck, I am easily getting an average of 65mpg in my civic hybrid, show me a gasoline car that is cheaper to own even after the cost differential. You won't find one for the amount of miles that I drive.


What killed the electric car is the lack of an on going cost. No radiator, no transmission, no oil changes, and no fuel filters. This is why you arent going to see any major car maker really pushing it. They make more on the maintenance than on the original sell.
PHEV are the next item car makers will make because it has the best of both worlds 2 engines (make consumers think they are being good little pleebs but still keep the ICE engine for the maintenance)

I heard a report the other day that now 50% of the people in the united states are on maintenance drugs.
Same theory, it isnt profitable to cure the ailment only mask for the rest of your life.

David Cabral

Is there any talk of building plug-in systems for Honda's hybrids? I drive a Honda Accord Hybrid and wouldn't mind a powerful battery. I get about 35 mpg on the highway, and wouldn't mind bumping up my mpg...

Kevin Trudeau

I see you've read my book, dan. I hope you also purchased the online subscription and are buying my vitamin supplements.

Kevin Trudeau

The drug corporations and the car companies just want to take your money and keep you hooked on their products. I on the other hand, only want to help you.


Valence sells a Lithium Ion Phosphate batter that is a drop in replacement for Lead-acid batteries. I wonder if you could buy all the components except for the batteries from them and then buy the valence batteries?


I'm with JRod. This thing doesn't currently make economic sense at all. But it's a start. It'll be interesting to see what they're doing in five years. Until then, I'll stick with gasoline.


Even A123's system @ $10,000 a pop is not a good idea. Take your $10,000 and buy a new central AC heatpump if yours is old, or put $10K worth of solar on your roof. Don't tweak a car that is already getting 60mpg.

BTW - it is obvious that the film, "who killed the electric car" movie came to all the wrong conclusions. It is clear that the battery technology is not ready yet for mass production. It is getting close. Safety, reliability and cost are important factors that have to be ready.

Buying 350 pounds of lead batteries sounds like a very bad environmental use of $5,000 also.


Battery range is 15 miles max. The cycle life is 800. 800 x 15 equals 12,000 miles. The cost is $5,000. $5,000/12,000 miles is 41.6 cents per mile just for the battery depreciation.

You don't replace the entire $5000 system in two years, just the batteries. Battery cost for the open-source project was only $800 but lifetime cost was 20 cents/mile because the batteries only lasted 400 cycles. These 800 cycle batteries cost more upfront but probably come in around 15 cents/mile. Of course gas cost for a Prius is only 10 cents/mile. This conversion is about getting off oil, not saving money.

Advanced lithium battery vendors claim thousands of cycles and high volume prices below $500/kWh. This gets battery depreciation cost down to 2-4 cents/mile. Gasoline and liquid biofuels can't compete with that, though they'll still be useful for long distance travel.


If firefly ever gets their battery into mass production, it would be a much better battery as a interim until Li Ion becomes less expensive.



I like the comparison of car maintenance to being on maintenance drugs. That was funny!

I guess I have to wonder how much maintenance we all do to our cars. Sure there are fluid changes and rare mechanical failures, but I do not think I spend thousands and thousands on maintenance. I think my biggest expense are tires, along with alignments and balancing, and that will occur whether it's an ICE or an electric vehicle.

Is there data out there on the projected maintenace costs of a vehicle?


What you need is a set of control algorithms that enable a (p)hev to work optimally with battery sizes from the current prius size up to say 100 mile range.

Thus, you characterise the engine system and car mass etc and the system works out the best way to use the electric power. You could add GPS and machine learning to the system.

For instance, it might notice that you go to the shops on tuesdays and can drive the whole way on electric.
It might suggest that you plug it in at the office, and that, if you did, you could go the whole way on electric.

Then, as you add KwH, the system makes the best use of them, but it still works well with a 2 KwH battery and a bit of regenerative braking.

It would be a good assumption that batteries will improve more slowly than people would like, and to build systems that work optimally with small batteries.

A clever algorithm could reduce the need for a larger battery.


doggydogworld has it right:
"This conversion is about getting off oil, not saving money." The Prius HEV was not cost effective for many years. This will change even more that it has already when the generation 3 Prius is released next year. You'll see the same evolution for PHEV technology but it will happen faster. The battery technology is here and the cost is already starting to come down. Lots of Lithium out there so the cost will be able to drop significantly.



It's not that I am a battery hater. I want to believe Mulder, I really do. I have been looking around for a couple months at conversions for cars, electric scooters, electric bicycles etc, but have always come to the conclusion that the battery depreciation is a deal killer. It's not that I wanted it to be, it just is. You could make the argument that ddw does, that it is better to spend money on batteries than oil, and I buy into that, but only to a point. If we are going to put a serious dent in our oil imports I think it will have to be competitive.

And to the anonymous poster getting 65 in his hybrid civic: Congrats! You have the world's best civic because rates that thing 45 highway which is 30% better than the 34 rating of the base model. And the MSRP is fully $8,000 more.




@David Cabral,
I haven't kept up with Honda's newer hybrid efforts, but they're earlier hybrids were (are?) all electric assisted ICE designs. You need to have this the other way around to convert it to a PHEV. The Prius for example is an ICE assisted electric drive. This has been a mistake for Honda in my opinion. I won't consider purchasing a Honda hybrid until they fix this. Of course my next car purchase will be a Series-PHEV like the Volt, also called an Extended-Range Elextric Vehicle (E-REV). Way, way better less fuel use than a parrallel/series HEV or PHEV llike the Prius.


Oh, the battery TECHNOLOGY is definitely there. Economics might not be, but technology is there. And here is a newsflash : economics wont improve on its own, without products being commercialized. The technology will only get cheaper and more economical if its on the market. LCD teevees, hybrids, solar roofs, all that is not shaken out in labs but on markets.

BEV time has definitely come, witness the reports from British Motorshow EV Village this year or just follow the announcements of new upcoming EVs from minor AND major players. Early adopters will pay premiums, as always, but the time has come.


Nope, EV1, RAV4 EV, and at least one other failed to catch on because battery tech was not up to the task at the time. Do you have a $500 deposit on an Aptera or are you just another whiner who won't put his money where his mouth is? Aptera EV is faster, more aerodynamic, lighter, and cheaper than EV1. There's an E-REV version if you don't want to be restricted to 120 mile range. GM said over and over that customers were not purchasing high mpg vehicles. It was true. What are YOU doing about this?


doggydogworld has already pointed out cost of battery replacement will be considerably less than total system cost. Consider other battery options may be available by the time this needs to be done. Li Ion may be cheaper by then. FireFly lead-acid-graphite battery could also turn out to be a better choice by then.

Mark A

$4995 buys, relatively, alot of $4.00 a gallon gas, considering the Prius's high mpg numbers. That could equate to over 50K miles. The improvements over stock do not appear to be attrractive enough to the majority of us. Especially with the added burden of carrying around these the weight of these extra lead batteries, in places the car wasnt designed to be carrying them. Perhaps thats why the Toyota engineers didnt design them in, in the first place.

But this is progress, and progress is what we need. Whats the latest on the Toyota A-Bat???

Bob Bastard

mds, don't forget to mention the fact that gas was hovering around 97 cents/gallon at the time GM 'killed' the EV1. I would imagine that factor weighted at least as heavily in their decision as the deficiency of contemporary battery tech.


$5000 is the cost of the entire system and the profit they have to make from manufacturing it - not the cost of the PbA batteries alone. You are buying a ready to install kit for $5000, not 5kWh of PbA batteries.


Over on there is lots of talk about NG conversion. $4000 to convert and $2000 for the compressor in your garage after rebates. I would convert a hybrid like the Honda Civic. You have dual fuel where NG takes you cleanly around town on $2 fuel and you still have gasoline for long trips.


Bob Bastard, Yes, absolutely, but I think E-REVs and BEVs would have sold to nuts like me if todays battery tech had been available then. I doubt oil will go back down to $20 a barrel in the future. $40 to $60 sure, but not any time soon on that one, if ever. By then cost advantage of E-REVs and BEVs will be well established, with even better models in the pipeline. Pure ICEs will no longer be able to compete. Think we're seeing a permanent shift to electric ground transportation starting.

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