Hacked Prius runs at 70 mph in EV ONLY mode!

Well known in the Plug in Prius community for his encyclopedic knowledge of the Prius hybrid drivetrain and electronics communcation system, Chris Ewart of Ewart Energy has announced a new plug in system which allows a Prius to be driven at up to 70 mph in electric only mode. That’s right. Seventy Miles Per Hour. The rather shakey video below shows Chris and his brother, founders of Ewart Energy taking their modified Prius out for a spin to illustrate the 70 mph EV only mod and switching between regular mode, ultra-high EV mode and enhanced catalytic converter/engine warm up mode. Even with the engine running, they are able to sustain over 150 mpg at highway speed, something which is almost impossible in a standard converted PHEV Prius and impossible in a stock Prius.

While the Prius can speed up to over 100 mph in a combined electric/gasolean power mode the software limits of the standard Prius hybrid drive system prevents the Prius from operating in EV only mode above 31 mph. While it is possible to drive a Prius in stealth mode – an operating mode entered into when the engine and catalytic converter have reached optimum operating temperature and the Prius’ electric motors and batteries can sustain momentum using electric power only – any thing more than moderate acceleration causes the car’s engine to turn on. It has been known for many years now that a Prius will enter into a high-speed EV-only mode if the car belives it has no fuel in the tank but has plenty of battery power remaining – allowing the Prius to be driven at up to 52 mph in EV only mode. Many hobbyists and PHEV conversion companies have used this to their advantage, working on various high-speed EV mods which work in a range of ways to fool the Prius into thinking it has no petrol and thus forcing high-speed electric only mode. However, all of these hacks so far have required the driver to pull over at the side of the road and ‘reboot’ the Prius when the battery pack reaches a low charge level and the engine is required again. It’s this fact alone which have put various people off.

The problem for many PHEV enthusiasts though is the knowledge that the motors in the Prius (there are two) are capable of a much higher speed and operation than the regular Prius ‘operating system’ allows for. In fact, it’s been theoretically possible for the motors which drive the prius to provide enough power at high enough rpm to result in fully electric highway speed driving.

Natrually, when Toyota launched their own pre-production prototypes and then small fleet of plug in hybrids they were able to reprogramme the Prius’ own computer systems to allow for the car to operate in fully electric mode at up to 60 mph. But this door has been closed to anyone wanting to do something similar to a stock, non plug-in 2004-2009 Prius. Yes, it’s possible to convert them to plug in hyrbids (I have one myself) – but until recently the high-speed EV mode operation has only been possible if the driver was content with pulling over and power cycling the car to switch out of it.

This morning, while checking my email I was pleased and very excitied to hear about Chris’ new control system, which does away with all of the limits of the OEM Prius system.

I’ll quote it below:

Ewert Energy Systems is proud to unveil our breakthrough Enhanced Hybrid and Enhanced Electric technology (patent pending).

Traditional plug-in Prius conversions have typically suffered from several limitations:
1) A stock EV mode that is limited to 34 mph.
2) Regulated emissions spikes in stock EV mode can
result in emissions up to 12 times the maximum regulation allows .
3.) Mixed mode driving allows for maximum power and is certified for
regulated emissions, but delivers an average electric consumption only
up to about 7kW. While this can yield mileages of >100mpg at speeds
below 40mph, it usually yields mileages well below 100mpg for highway
4.) “Forced stealth” mode is limited to 52mph and
requires a vehicle restart in order to exit. To attain speeds of
greater than 42mph, it requires MG1 to spin at speeds faster than it
would spin under any normal operating condition, potentially leading
to long term damage or shortening of the lifespan of MG1. Forced
stealth also requires clearing mandated emissions recording data and
can run the battery down to damaging levels if not exited at the
correct time.

The new system removes practically all the aforementioned limitations.

Enhanced Electric mode allows the vehicle to operate at speeds of up
to 70mph in electric-only and allows for seamless transitions between
electric-only and electric-dominant modes at any speed. Additionally, it provides
a controlled warmup mode to prevent increased emissions.

Enhanced Hybrid mode allows the vehicle to operate in a mode which
heavily favors the electric system over the gasoline engine. While typical conversions
will only provide up to about 7kW of power, this new system can
provide full electric power (around 25kW) before using the gasoline
engine. This creates the ideal parallel plug-in hybrid, providing full
power for acceleration when needed, but optimizing for best fuel
economy when in charge deplete (PHEV) mode.

Where a converted Prius may have previously achieved only 60-80mpg at highway speeds, a
converted Prius with this latest technology may achieve in excess of
150 mpg. An early prototype of the system was tested at Argonne
National Labs earlier this year and achieved 170mpg on the realistic
standardized highway test (a combination of 55mph and 65mph highway
driving.) For many trips, 200mpg is now possible without the use of EV
mode.During Argonne tests, this system was found to comply
with SULEV/PZEV emissions ratings.

These systems will be available at the end of the month with the 25
mile range conversion from Plug-In Conversions, Corp.

If you have any questions, please feel free to contact us at info AT ewartenergy DOT COM

It’s really excited me and I can’t wait to see and hear more from them. If they’ve broken the limits of the stock Prius drivetrain then there are going to be a lot more PHEV Priuses out there! Watch this space for more information and to hear if this kit will make it’s way to the UK.




Add yours →

  1. Andrew Bissell June 16, 2009 — 8:05 pm

    Hi NikkiThanks very much for alerting us to this.One small comment: I think they are Ewert Energy Systems not Ewart. All the best,Andrew


  2. Very cool.I am a bit sceptical about the MG1 and MG2 viability at 70 mph stealth. The design of the PSD would force these parts outside of there design parameters and it is widely speculated that this could cause a breakdown in the lubrication system of the motor generators. Only caveat would be if they were actuall in warp-stealth not stealth. Warp-stealth allows the gas engine to idle burning very little gas, but provides torque compensation to keep MG1 and MG2 within thier design specifications.-Dan <11011011>


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