No, I'm saying you can't FORCE it into EV, with the switch, above 34 MPH. If the car is happy, and you aren't asking too much, IT will put itself in EV up to 42 or so. You can 'request' EV, by letting up on the accelerator then pushing gently. If the computers don't detect 'too great' a power need, the car will stay in EV at 40 MPH just as it will at 25 MPH.

Perhaps I misunderstood Ken's comment to be related to forcing EV rather than letting the car decide.

EV is SAFE any time, it is only a question of when you want to use the battery. You can't hurt the car using EV mode, even forced EV mode. If you drop to a battery SOC of 2 bars (purple/pink and I have seen my car do this itself, not when in forced EV) the ICE will start and recharge the battery.
You can hurt your mileage though, by forcing EV on the uphill depleting the battery such that the ICE starts to recharge it and push the car along on a flat 25 MPH stretch where EV would be ideal and get you a lot farther than the hill you just conquered.

The difference between forced and 'car selected' EV is that 'too great' is a LOT lower when the car puts itself in EV than when you force it. You can easily climb a small rise in forced EV (without doing in the battery) that will kick out the automatic EV. But, YOU know it is a small rise, the car has no way of knowing the demand will not continue indefinatelyThe ICE is 76 HP, the electric motor is 67 HP and has a lot more torque. For regular 'around town' driving, with a bunch of batteries, the ICE would never need to run at all.

 

Let's talk this way...
Assuming your EV switch is on (sometimes it is called EVb mode), coasting on a down hill without engine on and speed is 30 mph.
When you're exceeding 34 mph, the EVb mode is canceled, but your engine does not come on, still coasting and speed can be increased on the down hill.
When you're exceeding 42 mph, the engine comes on. You'll consume 1 cc of fuel to start the engine. After that, you can still do coasting the down hill with fuel cut mode. Please note that engine is spinning but MFD does not show it.

Regarding to the EV switch installation, refer to following article...
http://priuschat.com/forums/kb.php?mode=article&k=5
A few dollers Momentary Switch plus some wires are economy solution.

Ken@Japan

 

I think I've got it.

Using the EV switch, you can force the car into EV sooner than the car would switch itself into EV, but only if you're in a situation where the car thinks EV is OK.

But if the car thinks it should be running the ICE, there's no way you can prevent it by using the EV switch.

Does that sum it up?

The only way to keep the ICE off above 34 is to coax it off and try not to trigger it back on. And the only way to do that is to have enough momentum to get up gradual inclines and develop the light touch on the accelerator pedal to just get a boost from the battery. The art of driving a Prius.

Thanks,

David

 

The max power of motor spec is 67 HP, but the bottle neck is the battery power (21 kW) in EV mode.


Ken@Japan

 

Yeah I saw that later when I was comparing the relative power of the Prius electric motor vs ICE and that of the TCH. So if we got better batteries, we could make better use of the electric motor's capabilities?

In any event, using the EV switch, the 21kW seems just under what I think is generally needed for city street driving. I can use it to climb a slight rise, maintaining 30 MPH, on the way home where the computer will kick out of EV if I'm not using the switch. It isn't a long enough hill to show any change in the battery SOC (on the MFD, I don't have a scanner).

 

Yes, I think you do!