EV Mode won't stay on

Hi Overlap,
No, current from the Enginer system is probably not causing this. The Enginer system will automatically stop transferring current as the Prius HV battery gets to full charge, if it is set correctly. To check this you can turn the car to ready while charging and engage EV and turn on the Enginer system. Over time the you will go to 8 bars. If you do not get all the way to 8 bars then the Enginer converter is set lower than optimum. After you are at 8 bars for a while, the ICE may start to spin, but with no gas going into the ICE. The tail pipe will stay cold. This is what the Prius does if the HV battery gets high. If you get 8 bars but the ICE does not start to spin, then your Enginer converter is set correctly.

My guess is that you never really got EV engaged. Sometimes it is difficult to know if EV really engaged. I have had that happen to me several times. Also your Prius HV battery may have still been to warm.

Do you have an EV switch independent of the Enginer system? I would recommend putting the EV switch onto the headlight flasher. This makes it very easy to turn off and on.

By the way, If you are ever down in the Vancouver Wa area you can stop by and We can check your voltage and current coming out of the converter.

Thanks,
Dan

 

Sometimes when the EV mode switch is pressed, the Prius won't go into EV mode. Usually it gives the triple-beep when this happens, but I have found a couple of conditions when it does not go into EV mode and also doesn't triple-beep. These are:

1. You didn't wait long enough after powering up; or
2. The EV switch is pressed too fast after it has been pressed the first time.

I get into the habit of turning the display to the MPG screen before shutting down the Prius. Then, the next time I turn it on, I know I pressed the EV switch at the right time and it went into EV mode if, and only if, it switches from the MPG screen to the battery management screen.

 

Actually, I think I erroneously started the 104oF thing a couple of weeks ago. It's actually 114oF. I have conclusively proven this to myself.... again tonight. I needed to rewire my EV switch in a hot garage. I tested the switch and got the beeps and the MFD display saying EV mode was unavailable. I immediately cycled through my scangauge to get the max battery temp. Sure enough, 1148 (114.8oF) was displayed. I opened the garage door and hatch and within a few minutes of stabbing the EV button every now and then, I didn't get the beeps.

I confirmed functionality of the EV button using the EVbutton xgauge. I checked temperature and it was 113something.

So, the limit for forced EV mode is 114oF. Also, purple bars on SOC will kick you out of EV mode. The initial ICE warmup excludes EV mode.

To the best of my recollection, those are the only causes I've seen which disallow forced EV.

 

My recollection isn't that good. To start, these observations are for my 2007 2G Prius. YMMV.

I forgot to mention the obvious forced EV mode prohibitors... 1. over 34 (sometimes at precisely 34, sometimes 34 is displayed and EV is still going) automatically drops EV mode. You can't get back in until you come down to 33 or 34 MPH.

Slamming on the accelerator will cancel forced EV mode. Get off the pedal and you can reactivate forced EV mode.

Did you know that you can't use cruise control to hold a speed while in EV mode?

Lastly, anybody with an Enginer system should have a separate EV button for a number of reasons. Mainly, the ability to quickly punch yourself back into EV mode when invariably you exceed 34 MPH is key.

 

I thought just cycling the Enginer switch (off then on) effectively send a request to the CPU for EV mode. It's just a ground signal toggle to send the command/request.

Pb

 

Yes, true.

While I don't know this for a fact, I'm not sure I like the idea of cycling the enginer on and off at the same frequency as the need to punch yourself back in to EV mode.

Clearly, powercycling the PHEV causes whatever its operating state is to reset back its powerup state. It takes a few seconds to sense voltage(s) and back the current down or shut the whole system down due to low cell/pack voltage, or whatever else it does when it reboots. While this might not be a problem at best, it can't be good.

The second issue is related to overheating PHEV switches. I read a brief comment on one of the blogs the other day about this. I can confirm I had a problem with my switch when I cycled it on and off about 5 or 6 times in a few minute period. I noticed a sickly sweet smell filling the car and finally a bit of smoke coming from the switch. Clearly the switch was burning. I shut down PHEV, let things cool, and it's been fine since.

So, I really don't like the idea of powercycling the enginer any more than I have to. Placing EV functionality on its own switch just seems to make good sense.