Hack the Prius

they have added those features with each new iteration. idk if anyone has ever hacked and improved the software, not to my recollection.

 

You can watch the OBDII bus. You can even alter some parameters.

 

If somebody wanted to. They could create (with information already available) create a system that would allow the Prius to use more battery power when it would be beneficial (when long downhill is coming). Or the other way around if it would be beneficial to charge or conserve the power in the battery. These could be achieved with SOC spoofing through CAN. Basically you would build a computer connected to CAN-line that would receive the message about hybrid battery SOC and then use some kind of S-curve transformation to SOC number and send the message out. S-curve transformation would be needed because you only want to alter the SOC when it’s (about) between 48…78%. I don’t know if anybody has actually done this.

Pulse and glide “cruze control” could be build out of just regular aftermarket cruze control that would be installed to pull down the gas pedal. But again I don’t know if anybody has actually done this.

But I’m pretty sure that nobody outside Toyota has gotten into the Prius system enough that they could install those things directly into control unit(s).

 

Complex, yes probably.

Proprietary language, I'm pretty sure the Prius has COTS microprocessors and most likely programmers are using a standard language to develop the various apps and interfaces. It's very, very costly to develop and implement a proprietary language. Top notch programmers are too hard to find to make them learn languages they can't use outside their current job. Reminds me of one of my jobs, we were a finally an all-C# shop that had transitioned thru several languages from FORTRAN 25+ years ago. Well we had an app that someone forgot about; I, as the old fart, was the only one in the office that had ever used FORTRAN. Of course I got the task to rewrite the app.

Dangerous, yeah probably not something I would want to drive after "tinkering" with any of the ECUs' logic.

I'm guessing that one could read out EPROM contents, play it thru a disassembler, and come up with some understandable code. Good luck if you pursue such an endeavor.

 

If I remember right, some of the Prius battery kits out there (Enginer IIRC) hack the Prius' system by sending a false state of charge reading during use. They tell the Prius' computer that the battery is at something like 75% state of charge most of the time, and then during acceleration it tells the computer 99% SOC to encourage even more amps to be drawn from the batteries. Generally this is done by running a variable power supply in series with the battery pack, which boosts the voltage up during use.

The Prius is very optimized in how it manages charge. If you think about how it behaves, it already has a behavior pretty close to ideal - when you hit a hill you push the gas pedal down farther and the battery is discharged for extra power. When you go downhill, you back off on the gas pedal and the car uses extra engine power to charge the battery. Sure there are circumstances where this could be optimized (eg. coming to 1 bar at the top of a hill and 8 bars before you hit a big climb), but I doubt you're looking at large possible gains - probably on the order of 5% improvement in mpg in a typical commute.

Therefore I don't see a lot of point in hacking the Prius' ECUs, except for in the case extra battery capacity is added and charged from the grid. In that case, it makes sense to fake a high state of charge to encourage the car to draw power from the batteries.

A Prius can certainly benefit from most of the usual eco-mods. See this page if you haven't already: 65+ Vehicle modifications for better fuel economy - EcoModder.com. I think a Prius with a 0.17 coefficient of drag is possible, based on this guy who did it with a Honda Civic! Such a Prius could get ~30% better highway mpg.