PiP Regen Behavior?

The engine is coming on based on the coolant temperature. Running in EV/Engine Off will eventually drop the coolant temp below the minimum allowed by the Synergy firmware (around 110F) and the engine will come on, taking the car out of regen. The A/C has little or no effect since it is electric. However, using heat will accelerate the cooling process. You can see this by watching the coolant temp while either turning the fan off or lowering the heat set-point to Low.

 

So much bad info in this thread. And so many people commenting on this when they don't even own a PiP.

 

Once the system is fully warmed, the minimum threshold drops.

Last month, I had the heater running with the engine still off when the coolant was at just 82°F.

 

i think it's in the o/m addendum that came a few years after i bought mine. something about the vagaries of descending yosemite sam and the potential for ice firing. i'll look around and see if i can find it. i know it's here somewhere...

 

I'm no Prius expert (planning on buying one), but could it be engaging the ICE for engine braking when certain conditions are met while descending, even if you don't change to "B"? Not sure on the specific roads, but I drove to Yosemite last year and used "L" (in the Chrysler 300 I rented) regularly on the many steep descents. I normally drive a manual diesel and would make good use of engine braking in low gears in such situations to avoid wasting energy by braking. With modern electronic fuel injection there will be no fuel consumption with engine braking and closed throttle.

 

I was able to see it doing this a few times this weekend, and I think it's kicking on the engine to soak up some of the regen. Can you see battery pressures/temperatures? My guess is there's some limit there the ECU will avoid. I also noticed that the engine would turn off when I took my foot off the brake/turned off cruise control.

 

I'm switching my guessometer to catalyst temp, probably the 2nd reading. I haven't confirmed this, but if I'm remembering my downhills right, I don't think the car has ever kicked on the engine when it was hot out and the battery was a less than full charge.

I had it turn on me yesterday in colder temps at higher speeds, but once it warmed up after a ~2k drop in elevation and I set the CC to 48mph to charge on a downhill, the engine didn't kick on at all.

 

I'm thinking more and more that this is the case, and that the ICE stays on and propels the car after the downhill for the exact purpose of letting the MGs "rest".

 

maybe the software is programmed to fire the ice after so many miles of regen, to prepare it for use.

 

My thinking exactly. As you can see from my video, regeneration actually continues after the ICE fires, though slightly slower.

What you should be looking at, Redpoint5, is if the MGs propel the car at all once the hill is done.
Is there any anomaly in power draw that suggest they are being spared and that the ICE takes most of the job propelling the car once the hill is done?

 

it's a shame to lose the regen, and have the ice fire, i hope they have come up with a better system for folks in hill country.

 

i wonder if ambient temp also comes into play?

 

The temperatures are closing in on freezing here these days (0'C/32'F). Today, while going down a tiny hill that takes about 20 seconds to go down and WITHOUT braking at all (just normal off-pedal coasting regen), the ICE fired up. It's never done that before (then again, it's never been this cold since I bought the PiP).
HVAC completely off. Charge level at about 90% from full.

 

i have a small hill on my way out of town. just enough to take me from 25 mph at the top to 35 mph at the bottom with foot off the gas. when i leave the house with a mile burned off of a full charge and temps below about 40f, the ice has fired every time for the last 4 1/2 years. i can defeat it by putting it in neutral until i get down to about 30 mph, but it's a 40 mph road, so if any traffic behind me, i'm out of luck.

 

Can't you have it in neutral at almost any speed?

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