Fuel Consumption During Typical Warm-Up

BobWilson measured the fuel consumption during warm-up. Perhaps a search of threads he has started would be fruitful.
Do note though that his result is not equivalent to wasted energy, since a fraction goes into the battery.

I cannot remember his method, but anyone with an android and the Torque app could log GPH readings and sum them in a spreadsheet.

 

On a tangent --
The Prius warm-up routine was set in part to keep emissions low. I personally would not care to pollute more to save what is no doubt a small amount of fuel.

 

I curse the engine warmup programming every single morning. My commute is 21 miles and after 18 months of tweaking I have when and where to switch from EV to HV down to the foot. The problem is that on my 35-minute commute the PiP goes through no less than three warmup cycles, and sometimes four, even though ambient is 65°F. The segments needing gas power are separated by a few minutes, which is apparently enough to make the car think it needs to warm up again. The warmup wastes gas because it runs the ICE for far longer than is needed, and by the time it is needed again it will have cooled off again. I can't believe the wear and tear from about 34 hours a year at 2 minutes a cycle is offsetting an even greater amount of wear and tear from something else.

If my understanding of the PiP's fuel consumption at idle are correct, the unnecessary warmups consume about 12-15% of my total fuel consumption for the commute.

In my commute case it increases pollution significantly.

 

that's why ice not starting at all is the ideal case, disregarding electrical generating pollution.

 

Interesting, thanks for posting.

Sounds like you may have to compromise with the car. Perhaps all HV for the first ~ 8 miles, and then EV ?

 

Warm-Up Cycle? On my 30-minute 17-mile commute, I only have 1.

Whenever the engine is briefly needed after that, reaching the 130°F threshold only takes a few seconds... which is just a tiny amount of gas. Above it to start with, the shutoff is immediate.

How long does yours take?

The only time I've encountered warm-up taking longer is when starting a new trip with an engine already partially warmed. Then it goes for a duration based on runtime rather than stopping at the usual coolant level.

 

what was this thread about?

 

That would significantly reduce my MPG. Right now I can achieve 106 MPG (by the display) for a 42.5-mile round trip with one charge (no possibility to charge at work). I get about 21 miles on a charge currently (my estimated range is currently at 21.8 on startup), but if I had to burn that EV going uphill on the way home it would be significantly less. The only real opportunities for me to improve my MPG are to hack the warmup cycle or go even slower on the highway (I already stick to 55 in the right lane).

 

I've always noticed that this car needs two warmup cycles. The first is the longest at about two to three minutes. The very next time the ICE engages - even if it's thirty seconds later - it will perform another mini-warmup (about 1 - 2 minutes). However, on my commute, each use of the ICE is separated by about 10 minutes. The car goes through the full warmup most of the time on each use.

 

Maybe your experience has something to do with your EV distance being well above what the typical owner ever has. The longer time might be related to battery reconditioning. Note sure.

10 minutes in between engine runs with it having shutoff at the minimum would do cause that cycle though.

 

You are getting ~ 50 mpg in HV mode. That is low considering your driving routine and suggests that EV is given the easy part of the route.

I still think you should try to plan your route differently. Do you have MPG figures for other -- protocols, for lack of a better word ? I'm curious how you would do if you left the car in HV the entire time.

 

Perhaps, but up to 50% of that energy is routed to the battery which in part explains your 21+ EV miles a charge.

 

I was curious how your MPG would work out with more typical EV range and liquid fuel HV values.

I assumed 60 mpg in HV mode, and 14 miles EV range. That works out to ~ 90 mpg.

 

[50 - 200ml]

Eggs must be very large in the UK. Using Chicken egg sizes - Wikipedia, the free encyclopedia as a reference (wikipedia knows EVERYTHING!) a large egg is around 70 gr, but it is dense, so only around 45 ml.

 

you can look at the sticky spreadsheet for a range of values.

 

I think I found the SS you mean, but it is locked from view to outsiders.

 

PiPLosAngeles,

Fuel economical (but not crazy) driving requires about 200 Wh/mile energy consumption at the wheel.

I started from that assumption, and
3 kWh usable battery
36% ICE efficiency
42 mile trip

-> 8400 Wh per trip
-> -> 5400 Wh liquid fuel

36% ICE efficiency -> 15,000 wh petrol
15/33.4 gallons = 0.45 gallons

42 miles / 0.45 gallons = 93 MPG.

Calculations like these are what make me skeptical of routines that increase pollution for what seems like at best very moderate improvements in fuel economy.

 

42 mile trip - 15 ev miles = 27 hv miles / .45 gallons = 51 mpg.

 

that's odd, i don't sign in or anything.