DIY Electric Car Forums banner

Toyota "e-Prius" Conversion

25740 Views 10 Replies 8 Participants Last post by  ElectriCar
As a current Prius PHEV driver (for over a year) and a firm believer in "KISS" (and an Electrical Engineer), I've decided that it is time for my wife to enter the world of EV'ing via a very simple Prius "upgrade" from Hybrid-Electric to All-Electric.

First, let's look at her driving habits: She is currently driving a 1994 Honda Accord that she drives about 5000 miles a year in our neighbourhood to visit friends and for some "retail therapy". Yes, it would be much more affordable for her to call a taxi. But, I want to retain her as my wife, so that isn't going to happen. She never drives on any 4-lane highways; she never drives during our frigid Canadian winters (January to April); and she never drives over 30 miles in a day (averaging about 22 miles/day) with a typical speed around 45 MPH.

I have a wonderful friend, Mony of Autodex Hybrids, who has gotten me a recyled, rebuilt white '05 Prius in perfect shape and is prepared to rip out the engine, gas tank and exhaust system for me. He also has already installed a used Hymotion L5 Li-Ion nano-PO4 battery kit and has two 4 kWh Enginer Li-Ion packs destined for this conversion.

So, what I will end up with is a Prius (or I should say an e-Prius) with a 50-mile radius (almost double her average requirement), top speed of 52 MPH and acceleration of 0 to 40 MPH in 15 seconds using the standard Prius 50 kW motor/generator set, CVT, converter/controller and S/W along with 13 kWh of additional battery energy in addition to the 1.3 kWh of OEM NiMH battery. Regen energy will still be restricted to only the OEM battery. Please see
A custom template will hold the CVT Engine input from turning and one of the Enginer packs will sit in the Engine space. The other Enginer pack will reside under (or in lieu-of) the back seat, while the Hymotion pack is beneath the trunk, replacing the spare tire.

Totally meets the specs required for my wife's driving habits, don't you think?

So, I feel that my only problems are driving in our Canadian December (around 25 to 35F); driving in July (around 80F); charging 3 separate battery packs each with its own charger but, mostly, smoothly switching the source of power from one battery pack to another.

What do you think?

~ Erik
See less See more
1 - 11 of 11 Posts
Please keep posting your progress. I am very interested in the outcome. I am currently trying to install a Prius electric transaxle into another car for an all electric vehicle. I don't have much experience with ev yet but I am giving it my best shot.

There are many issues when trying to convert a prius to all-electric.
Send me a PM to discuss.
What do you think?
I think that the challenge will be to convince the various ECUs in the Prius that there really is an engine there. Apart from that, you will end up with an EV that doesn't fit many people's needs (e.g. 52 mph top speed), but it seems to suit your wife's needs, so that's probably OK.

You may have to fake various sensor inputs, e.g. catalytic converter temperature, engine RPM, fuel level, and so on. The ECUs change their behavior depending on things like the level of fuel (e.g. limp home mode). It will try to spin the engine to get the catalytic temperature up to a certain value, and may throw a fault code and not move the car if it can't start the engine.

As long as you're comfortable with faking these things, all should be well. It should be an interesting conversion.
Please keep posting your progress. I am very interested in the outcome. I am currently trying to install a Prius electric transaxle into another car for an all electric vehicle. I don't have much experience with ev yet but I am giving it my best shot.

I hope that you are successful. There will be a bunch of these cars around.
I understand that it may have hill climbing issues without the ICE.
OK I too was thinking this would be a good option, buying a used Prius and adding KW to it. I wasn't thinking of removing the engine, just adding more battery so that with enough capacity the engine would not come on.

My main concern is if the electric motor can handle becoming the main motor versus short bursts they were designed to do. I know the newer ones have a manual electric mode where you override the engine and force it to go on electric. Still the mileage is very limited in those OEM designs and again, can it handle driving on the highway for 30 minutes at 150A or so?
With only one post I take it the OP was just telling us what his plans were. I was going to ask him how it was holding up with the new long range pack.
save the hassle, and use a 3rd party motor controller. tritrium wavesculpter 22 might do the job. Weird part, is the model 200 is about the same price.
Would be a lot easier to just do a PHEV conversion like calcars and size the pack large enough so the engine doesn't typically come on - which should be easy for your wife's driving.

Otherwise I would go the other route mentioned and just pull everything out and use another motor/controller and tie all batteries in different areas of the car in series. Then it would be highway capable if needed. Otherwise I think you will spend a lot of time with modifying software/firmware to get it to work.
With talk again of $5 gas in a few months, I suspect Prius prices will start an upward move soon. Again I think this makes more sense than building from scratch if it can be done without torching a motor after a lengthy drive.

I have a nice truck conversion, great at saving money but it's still a hack and there are issues I'd rather not have to address, ie reinstalling the AC system, making the ventilation system (vacuum operated) functional again, only brake is the parking brake etc.

Adding KW to a Prius just makes the most sense to me. I really just don't want to do a total hack on another vehicle, especially for the wife.
Just found this. Pretty cool and answered my questions. Did you know prius has a switch on european cars that allow it to run in electric mode only until the battery gets low? Leave it to the US government backed by oil to make them remove that damn switch so it will consume more oil by running the gas engine more!:mad:
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.