Converting your Prius or other Hybrid into a Plug-in Electric


Move over Chevy Volt, there is an alternative, now!  Imagine improving the gas mileage of the already best in class Toyota Prius an additional 25% on in-town trips. I discovered this is possible with the installation of the 4KW Enginer plug in upgrade. This boosts the battery capacity 4 fold from the base 1.3 KWH system in the base Prius.  For the last 18,000 miles we have averaged 43 mpg with our 2005 Prius in real world driving in the hills of NE Tennessee. With the Enginer kit, we have seen our mileage jump to 55 mpg over the last 2100 miles. A friend in the Knoxville EV club claims 120 MPG but admits he drives VERY slowly.  he system, installed on Feb 5th, has given us our five best tanks to date. Our results are shown below.

 Prius MPG Graph 

Having converted my truck to a plug-in hybrid and building an all-electric Jeep with Leslie Grossman of the Knoxville Electric Vehicle association, I expected to find challenges during the installation.  To my surprise, the kit came with all necessary pieces and parts and after about 12 hours of work the system was up and running.  If I understood how the high voltage relay worked on the Prius, I would have saved about 5 hours as I panicked when the car would not start.  A revised install manual includes these extra details.

The image below shows the kit with the charger, DC to DC converter, BMS, and batteries together in a neat box that fits under the existing trunk floor of the Prius. 

 Figure 1  Enginer Kit in the box 

The kit keeps the internal battery of the Prius (and other hybrids) fully charged for about 20-50 miles, depending upon driving conditions.  Because the internal battery maintains a higher state of charge, the car slips into EV mode more often allowing the engine to stay off much of the time.  Since we rarely run in pure EV mode with all the hills, we drive about 50 miles before the Enginer kit is out of power.   After plugging in for a a few hours the system is once again ready to go.

6/18/2019 7:01:59 PM

Can this be done with a 2008 Toyota Highlander Hybrid?

5/27/2013 9:30:15 AM

If you are in Europe a similar kit can be bought from MD-Tech at   Though there are some notable performance upgrades in the power converter output and BMS function and design. Retails at €3500 for a 4kWh kit can go 40km at 38km/h.

Brenda Martin Hrivnak
4/1/2012 9:57:50 PM

Again there is a grain of truth. But even if you get your power from 100% coal based electricity the emissions from electric drive are 50% less than a gasoline car according to the EPA. I did my own analysis using data from AEP (our local provider) which is 80% coal and A Nissan Leaf has 41% less emissions than a compaable Chevy Malibu. Granted powering the car from a solar array is even better but even if you use coal based electricity we are better off. Then there is the added benefit that the power is 100% American produced and not based on imported oil.

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