The FreeUs Prius?

Chris and Andrew Ewart, the guys behind the phenomenal 70 mph EV only prius (which I’ll call the FreeUs) have responded to some of the negative comments they had surrounding their intial announcement with a much better quality video illustrating their hack in operation on an eight-mile trip.

Since their announcement earlier this week (which was quickly followed by a statement from Plug In Conversions proudly announcing that the Ewart Energy’s breakthrough setup would be an optional part of their Prius conversions) there has been a flurry of comments on the ins and outs of the breakthrough.

While some have questioned the engineering principals and wisdom of purposely hacking a vehicle to run outside of Toyota’s own operating code of the Prius, many have congratulated the team for their hard work and perseverance. The Prius Chat messageboards have been a buzz with folks deconstructing the technical challenges which must have faced the duo in their work, not to mention those who are trying to duplicate the work of the Ewart Energy team for use on their own car!

The original announcement was also treated with scorn by Toyota, who have openly questioned the wisdom of the Ewart Energy modifcation. Combined with the rather poor quailty video which accompanied the original announcement Andrew and Chris have had quite a lot of unanswered questions they felt it nesseary to answer.

Today, they’ve released a new demonstration video showing an 8 mile test-drive using mainly battery power at highway speeds. It’s a much more informative video than the last one and they’ve also answered some of the questions raised by the intial announcement.

Chris has stated, on the EAA-PHEV list:


There have been several comments, including comments from Toyota, claiming that our new enhanced EV and enhanced hybrid modes overspeed and damage the motor generators. We would like to clarify this is not the case and that we do not overspeed MG1 or MG2 in our system. In fact, this was one of the problems with the existing “forced stealth” mode (when used at speeds > 42mph) that we were addressing. Our system utilizes both motor generators and at certain speeds, spins the ICE without injecting fuel (aka. ICE-spin.) This is the same way that the Prius does ICEspin at highway speeds. For more information about how the Prius’ power split device works, please see the following helpful explanation with interactive flash animation:

Also, in our initial announcement, we intended to thank Steve Woodruff of for his help in supplying us parts, a place to do some initial research and providing his insights into how the Prius works. While the initial research didn’t pan out to be the solution, we did learn more about the Prius from his help.



The video below shows the excellent interface they’ve used and gives some hints as to what to expect if their project ever makes it to the open source community, which both Ewart Brothers are known to support through their work on the Prius Plus project.





Whatever the outcome of this project and while the intellectual property of the Ewart Energy team may remain commercial for the time being it certainly has rekindled the enthusiasm in the plug in prius conversion scene and perhaps opens up the option of a plug in prius conversion for existing prius owners who want more fuel efficiency but also want a full speed EV.

Well done, Chris and Andrew!