07 prius "cannot change to EV mode now"

Try it in the morning when the car is warmed up. The hv battery temperature maybe too hot in the middle of the day, won't let you get into ev mode.

You knowingly bought a car with a check engine light on?

 

The battery is too hot. You can't fix it, it's doing what is suppose to do. Ev mode is not really a mode to drive in, simply used to move your car a very short distance. Like out of your driveway and into the street.

 

check the battery cooling fan.

 

There is nothing for you to fix, the HSD is programmed to look after itself, and the behaviour you described in normal.

I'm inferring from your posts that you have installed the EV switch so you can drive your Prius on electric as much as possible. If this is the case you need to stop doing this now or risk prematurely killing your HV battery. The EV switch should be used very sparingly and for things like moving your car from the driveway into the garage or vis versa; or a short distance in a covered car park.

The Prius is not an EV, it is a hybrid and trying to drive it like an EV will not only possibly damage your HV battery (by prematurely ageing it) but will more than likely result in a poor MPG over the long run.

The same goes for trying to "force" the car to drive on just the electric motor when it would rather use the ICE and electric or just the ICE on its own. My experience is that you can seldom do better than the HSD. Hypermiling techniques excepted.

I'm sure you will have questions, so please ask and I and others here can answer them for you.

 

I do not suggest converting your Prius to a plug-in (as a matter of fact, I highly discourage it).

The Prius is not a good candidate for EV conversion for many reasons.
1) It is designed as a gasoline (primary) car with electric assist. It is for this reason that the electric motors do not have enough power to safely propel the car. With electric mode only, the car is really underpowered and not safe to drive on the streets
2) The Prius has advanced, high-tech monitoring systems (called ECU's) that all work together to make this engineering marvel work. Adding more battery capacity requires modifying what one ECU sees which causes multiple problems with other ECU's.

There are other numerous reasons why the Prius shouldn't be converted unless you're going to gut the HSD and add an electric drive system that can handle the requirements. The stock Prius electrical system cannot handle the requirements on its own. It needs the gas engine and the gas engine needs the electrical system. They have a symbiotic relationship.

 

Well, Enginer plug in conversion is the least intrusive and therefore the safest but, its also the conversion that gives you the least benefit in mpg. There are also numerous problems with it as well.

 

"...to make this engineering marvel work."

Prius and engineering marvel should never be used together in the same sentence....unless you were being sarcastic.

 

Huh????