PHEV Prius

Hi there,

I am in exactly the same boat. I spent about a year designing a BEV conversion, and finally decided I would be better off with a PHEV (though eventually I still really want a BEV). I don't know that there is anyone on the list with a working PHEV, but there are a number of people (myself included) who are interested and thinking about it.

If you haven't already, you should take some time to study all the info here:
Prius PHEV - EAA-PHEV
Down at the bottom is a good summary chart of all the different conversions currently in the works, their status, cost and estimated range. They also have an excellent mail list, where a number of the folks working on the cal-cars open source (PriusPlus) conversion hang out. Some of the commercial converters are on there and have been pretty helpful too.
Maillist - EAA-PHEV

I'll try and answer your questions as best I can.

It varies from about $3k to $40k. $30k-40k will get you a top of the line professional install with custom controllers, state of the art batteries, about 30 miles EV/60 miles 100mpg+ highspeed) and more or less guaranteed performance. $3k-$6k is about the cheapest lead acid DIY you can come up with that will still give you ~10 miles EV range. Check out the chart on the EAA PHEV page for more details.

A commercial conversion can generally be done in a few hours. At this point a Cal-cars Prius+ will probably take a few weeks of gathering parts, and a weekend or two to complete. This can be sped up to a day or so if you buy the complete kit for ~$6-$8k from a place like:
Plug-In Supply Inc of Petaluma California

About 8-10 miles for a bottom end lead acid conversion, 30 miles on a commercial Li-ion conversion. Driving faster than EV mode, you will generally get 100mpg+ for about twice this distance.

Mostly its still 34mph for true EV mode. Because the battery is full longer, it is much easier to get into stealth mode above 34 though. The pluginsupply.com folks mentioned above in coordination with luscious garage are experimenting with a trick to get 54mph EV mode though.

For lead acid, you are probably looking at ~4 hours. Partial charging is not recommended as lead acid will loose capacity if not fully recharged. The chart on PHEV EAA gives you an idea of charge times for other conversions.

I believe Hymotion is working with A123, not sure if there are others.

Most DIY and lower end conversions parallel a secondary pack with the original, either through a big relay/contactor or a dc:dc converter. This simplifies things as you keep Toyotas battery controller in place, and if you have any problems the primary pack is still there to make your car act like a normal Prius. Most of the higher end commercial conversions replace the oem pack altogether, and use their own custom designed battery controller to replace the Toyota one.

I am unaware of any attempts to make any modifications to the regen system.

In my opinion there is no perfect answer currently, but things are far enough along that if you want a phev you can build one. Lead acid conversions are cheap upfront, but you will have to replace the $1000 battery pack fairly frequently (maybe 12-18 months?). Li-ion conversions are very expensive and complicated, and there is not much DIY activity here yet. There is a group within cal-cars looking at the Nilar NimH as a possible way to get a more advanced battery at a reasonable cost/complexity for DIY conversions.

For myself, as much as I dislike the idea, I'm probably going to start with a straight lead acid cal-cars conversion. By the time the pack is ready for replacement, I hope the Nilar solution will be ready to go and I can upgrade to NimH.

If you haven't read it yet, I tried to summarize the basic concepts and challenges encountered in trying to do a phev conversion here:
http://priuschat.com/forums/prius-technical-discussion/44650-phev-experimental.html#post584972

Rob

 

Plenty of info. Check out the EAA-PHEV group, for starters.
.
_H*

 

You can do it for $4k, but SLA is really your only option. I agree that dropping 250 lbs of lead in a Prius isn't exactly appealing, but its really the only option in that price range. The biggest con right now is pack life, you're probably looking at another $1k pack every year or so if you cycle it fully on a daily basis. IMHO this could be improved if you paid more attention to battery balancing. They currently do none. My plan is to go with 20X individual isolated 12V chargers to address this issue. Its about the same price as the big charger (~$800) but you get balancing for free. Just have to be careful that all 20 chargers work every time, or you'll cook the one battery that didn't charge :biggrin1:

The next step up is the Nilars, at probably $7-8k for a cal-cars type conversion. The BMS is still a work in progress though I believe.

PHEV conversions are probably not financially feasible at the current time. You have to want it for other reasons.

Rob

 

I agree. The mail list linked above is easily the single largest concentration of people working on diy phevs you'll find anywhere. The cal-cars Prius Plus open source plans are largely the collective work of the folks on that list, and like most open source projects they are always being updated and seeking folks to help push the design forward. For me thats part of the reason I plan to work with the cal-cars design, so I can eventually help give something back to the diy conversion community.

Rob

 

There was an article in "Home Power" magazine about an engineer in Colorado who plunked down 25k for a 2008 Prius, then immediately drove to a PHEV conversion facility (can't remember the name) and plunked down another 32k (yup, 32 big ones) to have his warranty voided and his car converted to PHEV. He did this because he wanted to make a statement, not because it made any kind of economic sense. He would need to circumnavigate the globe under electric only mode in order to recoup the costs.

As another poster said, the conversions can be done but don't make economic sense at present. There is also some question about the actual emission reductions because in a PHEV, the gas engine does not operate in its most efficient mode.

Verdict: best to stay with a normal Prius until Toyota and others release a PHEV designed from the wheels up to be such.