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Discussion Starter · #1 ·
I'm sure it's a little early in the life cycle of the CT is ask this, but I wonder if or when someone has looked into modifying/reprogramming some of the behavior of the car's control system. Using a handheld programmer and "tunes" accessed via the cars ODB port.

For example, I would really like to raise the speed at which the EV MODE disengages from 25 mph to 30 mph. I would find this very useful for residential driving at 25-30mph. I like the add'l battery only powered acceleration EV MODE allows, but could use a little more "top end" in EV MODE.

Maybe the electrical output of the electric motor can be further enhanced in SPORT mode to say a 750W boost over the 600W currently?

Maybe EV acceleration in other modes can exceed north of the ECO level on that left gauge?

Clearly these types of mods would never be Lexus/dealership approved, however, in the world of auto modification we tend to find some limits to push to get that additional performance. As we all know, manufactures typically leave some performance (horsepower or battery output) on the table in the name of efficiency, warranty, or in this case battery longevity, etc.

Just curious if the control system programming CAN be modified, with the hopes to enhance the battery performance down the road. Just think if someone can come up with an auxiliary, Li battery pack that say is a drop in replacement for all that space occupied by the spare tire and that styrofoam organizer thingy?!?:eek:
 

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Been idly looking at mods :

EV mode - not sure here, could be a location specific thing. When the car is up to temps (and is allowed to give or receive more Amps) I can gently accelerate to 30 and beyond on the flat. I'm not convinced the motor has the grunt to accelerate much past 30 although it can sustain 40-45mph quite well.

Upping the power - was reading about someone using forced induction on a Prius. On both supercharger and turbocharger, the 0 to 60 wasn't changed but the economy and flexibility of the car improved no end. Speculation was that the acceleration was the same because the hybrid control system was able to sense the total amount of power being delivered and would go easier on the motor. So I think we'd need to hack that to get more acceleration.

Li-ion batteries - if you Google "Plug in conversion kit Prius", you'll probably find a kit where they add 2kWh,4kWh Li-ion battery packs to the existing battery pack (under the boot) to turn it into a PHEV. That does stuff with Hybrid Control System's brain as well to allow electric only at 60+ (I think). Electro-mechanically this should read across to the CT, not sure about software. Linky ... (there's another at Pluginplanet.co.uk but that's giving me a DNS failure error at the moment)

Edit/addon - looks like there's 2 competing PHEV mods, Enginer and Pluginconversions (PICC). Enginer adds an additional battery array, PICC replaces the factory battery. As an electronic/electrical engineer, I'm curious but skeptical - something to be contemplated after your warranty has finished. (I made a couple of corrections too)

Stuff I'd like to mod :

Motorway battery charge level - My CT charges the battery up to 80% when on the motorway. That takes energy from the engine (duh! :)) and therefore costs fuel on short runs. What I don't like is that combined with the 80% battery charge hold programming (to avoid popping the battery), taking the charge to 80% on the motorway means there's no headroom to harvest energy when you leave the motorway. You'll not be staying at 70 forever, you have to slow down sometime ... Seems a shame for some of that kinetic energy not to find its way into the battery.

So, change the motorway charge hold level to aim for 60%, you still have battery KERS boost when you need it and there's more headroom for energy harvesting when you leave the motorway (or Interstate).

Traction/Stability Control - heard stuff about these (the Autoguide linked report) and experienced them to some extent. Our Traction and Stability control systems are quite aggressive, it could be good to be able to dial those back somewhat to up the fun in the corners. Not really thrown my CT at enough quick corners to see how it behaves though.

There's not much else in the way of tuning improvements, at least not that I've spotted. Ideas include : Air Filter, Fast Road Cam. However, I can't believe any fast road cam would be better than an electronically controlled and optimised VVTI set up. And if you did up the power of the engine, the Hybrid Control System would probably get wise to it quickly as with the early gen turbo/supercharge Prius project ...

That PHEV Prius kit might be worth a longer look, although I suspect we'd lose something of what makes the CT so intuitive to drive by changing to the engine control system that comes with the Enginer kit.

PS One of my angles for being interested is the potential of putting the Prius/CT powertrain into a kit car half the weight of the Prius/CT ... That could be spectacular. The 134bhp is about the same as what my Puma had, which was 300kg lighter than the CT. Cutting more weight off that would create a little bundle of fun even before potentially upping the power.
 

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Discussion Starter · #3 ·
Interesting.... In no way shape or form will my CT stay in EV MODE if going over 25mph. Sounds like this is a programmable set point in the control system. Now we just need to find a way to change it. :cool:

Now I CAN keep the EV light on (ICE off) up to 45 mph in the other modes, if like you say, I accelerate very slowly, keeping the needle at or below ECO on the left gauge.

But I like the greater acceleration EV MODE allows. I guess I can turn on EV MODE when starting from a stop, accelerate up to 25mph (at which point the car will automatically disengage EV MODE), then back off the "throttle" to keep the ECO gauge below ECO, and continue to gradually accelerate/drive in another mode while trying to keep the ICE from firing up. Of course all this only lasts for a mile or so until the battery is drained..... hmmm, yeah, need more battery capacity.;)
 
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