34 MPH EV Mode Limit - Can it be changed?

Oh tell us wise one! How

 

I don't see the point.

I also can't see Toyota saying, "oh, OK we never wanted Americans to have EV mode but seeing you have hacked the system to install it I guess we can sell you a firmware upgrade (if you can call it that) to put even more stress on the battery pack, then expect us to warrant it."

I really would like to know why you want this?

 

In the downhill areas you don't need to be in EV mode. You can coast down them quite easily. I have one segment of road curing my school commute that allows me to coast for about 5 miles. Simply lift off the gas pedal and then very gently reapply pedal pressure till the regen arrows go away and the EV arrows engage. You are using a miniscule amount of EV energy so it's no big deal. This works for exiting the freeway or coming to stop signs as well.

Driving in straight EV mode is generally accepted as not the most efficient way to drive the Prius, especially for long stints. I could be wrong but that is how I read it.

 

I believe you hit the nail on the head there. Stealth mode is far better suited to this type of situation, and there is no 34 mph limit on stealth mode.

The current belief is that the Toyota factory PHEV test vehicles have had a software modification that allows them to go EV up to 62mph. Its thought that this is primarily done by increasing the max rpm spec on the motor to 10,000 rpm. Supposedly it was found under further testing that this higher limit presented no additional risk to the MG. Much of this is still conjecture, and no one knows specifically how they make the change. If it is software only, it bodes well for someone being able to figure it out eventually.

I would agree that on a standard Prius this is not really useful. On a PHEV converted Prius, its an entirely different matter. The folks at:
Luscious Garage | Hybrid Specialists
are working on a modification they call "Forced Stealth Mode" (FSM) which effectively allows EV driving up to 54mph. They are incorporating this into their PHEV kit. As I understand it started out as a simple kill switch on the fuel pump to prevent the ICE from starting and simulate the out of fuel mode. They have refined it now to a direct controller signal, and automatically clear all the faults you would normally get. I think you still have to pull over and shut the car down to get the ICE to restart though. The idea is, that if you don't need to go over 54mph and commute less than the range of your PHEV pack, you wouldn't need to start the ICE at all. That would be cool for me, as most days I commute 7 miles at ~42 mph top.

Rob

 

The biggest reason I would like it is for the gliding ability. As Evan said, being able to propel the car to 62 would not work so well with the current pack. With the current pack, you can travel nearly 2 miles on a pack that is at 8 green bars. If you were allowed to go up to 62 you would probably drain it within a mile or less. With a 62 mph glide capability you would be able to build up more speed for the larger hills and keep the ICE from running. And, as has been mentioned many times here on Priuschat, running on the battery is really an inefficient way to travel due to all of the conversion losses in the system since the power ultimately comes from the gasoline in the tank.

 

Not true if you are on the first segment of your trip. I just encountered this today. There is a 1/2 mile downhill slope I can easily reach 40mph without the ICE, but since the engine wasn't up to the proper operating temp, the ICE ran. So, I slowed down to 32mph and used the EV button. I am lucky that no one was behind me. I too wish I could go 40mph in EV mode only. There's another segment on my trip that I can go almost 2 miles without the ICE but if the engine becomes to cold, it will start back up. It just seems inefficient to me. I know it won't be changed but it would be nice.

 

Umm - why couldn't you just either add a bigger battery or just more of them? That, and obviously hymotion.com/priusplus.org etc have found a solution to this?

 

And then the ICE did start and run when it was ice cold and due to the depleted charge state of the battery plus the power demands placed on it by the driver, accelerated wear and elevated emissions occurred.

Yep, now I see why you want it.

I have a half mile down hill at the start of every journey but I would never do that part of my journey in EV (I have EV as standard) because that is the perfect opportunity for my engine to warm up under controlled load to avoid accelerated cold start wear and high emissions of driving a cold engine under load.

 

I don't believe this is a situation in which you would want to be in pure EV mode either. At the start of the trip you want the vehicle to warm up as quickly as possible before you have to put it under any real load so in this case your situation might be ideal for max efficiency. By semi coasting down the hill with the ICE on but with a low load you can help achieve a better warm up segment than I could on a normal flat road. Same goes for the return trip home, it's better to be at full operating temperature while climbing the hill so the MPG impact is less than if you had to climb this hill in the morning. I'm at work and distracted so I may be missing something and just talking out my rear. lol

 

Its a lot more complicated than that, but yeah thats the basic idea of the PHEV conversion. To my knowledge the LG folks I linked are the first to offer a high speed EV mode. The SOC spoofing controller cal-cars is working on will greatly reduce the need for this, as it maintains SOC to the point where stealth mode is almost always readily available even at fairly decent acceleration. Of course this wouldn't help the situation described, as it doesn't affect the warmup cycle.

That is true. About all you can do is look into a block heater to get you through the warmup cycle faster, and maybe partial grill blocking to keep the engine from cooling off so fast.

Rob

 

This is not true. I'm already several miles into my trip so the engine is not ice cold and I have 6 bars on the battery so it's not depleted. From the time I start the car until I get to the highway takes about 1.5 minutes. Then I drive 60mph for 3 miles on the highway. Then I make my turn to go down a surface road that has a 1/2 mile downhill slope. This is where it would be benificial to be in EV mode only at 40mph. Besides my oil filter has a check valve in it and I run Mobile 1.

So, you see, I start my trip with the ICE running also.

 

Has anyone found a way to get past the 34 mph EV limit without upgrading to a plug in kit yet?