Gas on to heat car - does it defeat the purpose

If you can't understand the difference between a separate power supply and the car's battery (or choose not to), then yes, I agree.

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That's a good way to boost MPG and MPGe. Just use another power source for heat.

I think it works down to 22 deg F but what would be the temp coming out of the vent? Blowing out 50 deg air will not help.

 

when you use the ice for heat, a LOT of heat comes out of the vents with a powerful fan. when you shut it off, the cabin cools down very rapidly. fresh air is continually entering the front of the cabin and exitinf the rear. it takes a lot of energy to overcome that.

 

Just selecting Recirculate eliminates most of that cold air. Some of the rest is probably leakage that can be sealed out. You want at least a little fresh air, but it doesn't have to come in at high velocity or volume.

 

Double post, sorry.

You are correct.
I am not used to the unbelievable low temps you all see now...

This issue may be divided into two:

1. Pre-heat while plugged.
Good for defrost and de-ice windshield and initial comfort. Probably good for those driving only 1-3 miles.
This can probably be easily addressed by Toyota in next gen.

2. For trips over 3 miles, heat must come from one of the on-board sources and it may be that the best way is from the ICE. If coming from the traction battery it will put extra stress on it (on top of the EV driving) and will eat 'EV miles' anyways. Prius ICE plus the EHR are quite efficient.

 

Actually, running the ICE - especially long enough to heat the cabin - ruins fuel economy on short trips, and even some medium-length ones. That's why my prototype heater uses a separate battery for power - no effect on range beyond the weight penalty, which is less than that of one grade school child. It should also provide modest heat for an hour or more.

 

Lithium battery power output drops as well. More reason for ICE to become team player in propulsion as well as heat.

I accept the fact that non-ideal condition result in lower efficiency. When comes Spring, it will go back up. It is the year round average that ultimately matters.

I am approaching another 1,000 miles. My gas consumption MPG (ignoring electricity consumption) is 87 MPG with 40% EV.

My first year average was 100 MPG with the same EV ratio.

Despite ICE running for heat or to assist lithium battery, the difference in consumption is 1.5 gallon (in about a month). I am not going to worry about bringing in another power source to defrost and warm up the interior, for diminished return.

 

I don't expect everyone to be interested. Our consumption is more like 68MPG average, so more EV miles would help.

 

My average for this week of horribly cold weather here in Minnesota is 55 MPG. That's outstanding fuel economy compared to what my 2010 could deliver. Don't lose perspective.

I care, hence this video I captured yesterday...

Preventing window reflection for the camera means covering the dashboard with a black mat. Unfortunately, that covers the vents. To keep the windows from fogging up as a result, I have to crack windows to circulate fresh air. Fortunately, I have a heated seat and heavy clothing. It worked out... and I captured great data showing what happens when you don't use the heater in extreme cold with a plug-in.

The Prius was parked overnight in my unheated but insulated garage. That allowed the drive to start with the system at 28°F. Of course, it took me 14 minutes with the car running outside to finally get all the filming equipment setup. That ended up consuming 2% of the battery-pack capacity that was available. Oh well. At least I'm refining the quality of the app-data capture coming from my smart-phone.

Watch the coolant temperature in relation to speed. You'll see the engine shut off (RPM of zero) a number of times while HV driving (after the plug-in capacity has been depleted). The interplay of gas engine and the 2 electric motors is quite dynamic, thanks to the power-split-device. That flexibility is how high efficiency is achieved.

8.5 miles of EV was the outcome. Then, the engine fired up with the remainder of the trip in HV. The end result from the 17.3 miles of driving with the contribution of 3.0 kWh of electricity (which includes charging losses) was 96 MPG. That's great!

 

^^^ great post John!

What would you estimate would have been your average fuel economy for the week in your 2010 if all other variables were the same?

 

Tried it yesterday on the driver's side only, so I had something to compare with. Came out this morning to find the driver's side slightly misted and the passenger side clear... Temperatures were too high for a real problem, will feed back more when they drop (we have unseasonably warm 10C, so about 50F overnight at present, due to high winds and relentless rain. Please don't send us your polar vortex to follow!).

Anyone else try this or any other demister solution, and did they work? Rainex is the other one that gets mentioned.

 

nice one john, thanks! interesting to see that coolant temp only dropped a few degrees in that weather, in the before the ice fired.

are you saying it had the opposite effect you were going for? btw, 50 degrees and rain coming this weekend, thanks for sharing!

 

Close to 40 mpg.

 

I'm talking about 41MPG with our hills and with the engine idling for several minutes, on a route that's mostly medium speed highway. That's not so fantastic for a PHEV.

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Wow! Is that one way? What is the length? How much EV are you able to use? More details!

 

A trip the the veterinarian in cold weather. We warmed the car for about 3-4 minutes, then drove about 9 miles, including one steep uphill. I was able to use up most of the EV range, but that leg of the trip was still 41MPG. Coming home was only slightly better, with the EV range exhausted. Similar trips in milder weather usually yield about 68MPG.

 

Yes, with the heater running, mpg do drop in the winter. But, small price to pay to not getting hypothermia, especially at zero degrees or colder! Spring, summer, and fall, mpg do improve, no surprise there.

DBCassidy

 

And if there is a third option, why not try that...?

 

Is everyone overlooking the obvious? An engine block heater?

Sure you still have to fire up the ICE. But it would be an extremely fast warm up cycle plus you have quite a bit of heat their ready to go. Plus you get the advantage of the ICE being at a more efficient temp.

Also hope that anyone complaining about this problem has at least done the cheap and easy thing already...grill blocking.

 

A block heater is a (partial) solution for those who don't mind having the ICE run. I did do grille blocking, but it doesn't follow that if I hadn't I'd somehow have no right to not want the engine to run.