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.
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.
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.
The kit is not for the faint of heart, as the dash needs to be pulled apart to install a switch on one side and to and make 3 connections on the other side. Then, the right side channels and rear side panels are removed to run the wires to the dash switch, tie into vehicle power and feed the BMS. Finally one must drill six holes through the trunk floor and frame to secure the box.
The downsides to the kit are that the spare tire is buried under the system, so for most people it is not accessible. We solved this issue by sticking a can of Fix-a-Flat® in the car, similar to what Tesla does. Another downside is that you lose the handy hidden storage under the floor. But the Prius still has about 20 cubic feet of storage: nearly double what is available in the Volt. When fully installed the system is invisible. Our “trunk” looks like that of any other Prius. The only obvious differences are the plug mounted on the rear bumper for charging and the switch on the dash to turn the system off with the status LEDs
After wrestling months getting hard to find parts and waiting for replacement parts on my other conversions, it was fun to be able to finish a project in a weekend and experience the results. While one does not gain a full EV “grin” from such a conversion it does take us one more step toward reducing our need for