Warm up time?

[ad2001]

Hi, I just got my new 3rd Gen Prius IV a week ago.

How do I know if my car is warmed up after a night-long parking? I usually start my car and wait until I don't hear the engine noise, which usually takes 30 secs to 2 mins. However, I know that even if I have many bars in the battery indicator, I still can't use EV mode over 10 MPH. Also, I notice that my car is not very fuel efficient until I actually hit the road for a couple of miles (MPG bar is always around the 25 mark ). Is there a way to know when my car is completed warm up?

Thanks

Kelvin

[spiderman]

Originally Posted by ad2001

Is there a way to know when my car is completed warm up?

Without a guage like ScanGuage you won't know for sure. You really don't need to, the Prius will take care of itself. And yes, as the temps get colder the warmup period gets longer and mpg gets lower. It was 30 degrees this morning here and mine took about 5 mins before it would shutdown at a stop.

With that said, if you want to reduce that warmup time, I suggest getting an engine block heater and plug in about 2 hours before you leave in the morning. I intend to do this soon myself.

Peter

[qbee42]

Warming up your Prius wastes fuel. Start it up and drive. Best mileage will come from not pushing it too hard for the first bit, but a stationary warm up period is a bad idea.

As mentioned above, a block heater will shorten the warm up time, but the same advice still holds: start it up and drive.

Tom

[FireEngineer]

When you start your car and wait till the engine shuts off the engine temperature is about 103F, the end of stage 1. You have to reach 157F for about 10 seconds to get into full hybrid operation. Having a ScanGage does help. But as has been said, start it and drive it, gently at first. And don't use EV if you can avoid it except for very short movements.

Wayne

[a64pilot]

I'm not so sure warming it up wastes fuel. I say this because until it is warm, the car apparently is more agressive in it's traction battery use and that of course has to be made up either by fuel from the tank in one form or another. Any potential energy the car has from being on top of a hill or kinetic energy the car has of course came from gas.
So is it worse to burn fuel to let the car warm up and let it charge it's traction battery while doing so, or is it worse to drive off cold using a lot of traction battery that has to be recharged?
I have tried allowing mine to warm up and have driven off cold. I can tell you that I get to 75+ MPG bars faster if I allow it to warm up and have suffered no mileage hit that I can detect by warming it up.
On your block timer, buy a cheap timer made for a coffee pot and set it to start warming the car, that way you don't have to remember to plug in the block heater, it's what I do on my Diesel pickup. You have to have a high amperage timer though, like one for a coffee pot.
I have not experience cold weather yet though, so warm it up when it's 75 OAT is completly different of course

[ad2001]

I have to push it to the "red zone" right after I start my Prius because I live in a hilly area and I need to climb up a few hills before arrive to the down hill part of my commute.
After this initial up hill part, most of the rest of my 3 miles commute are either down hill or flat. I noticed that my car is still not warm enough run in EV mode higher than 10 MGH when I arrive. It usually takes 15 to 20 mins for the entire drive, and I'm not sure why it's still not warm enough for that much time. Does it have anything to do with how much I drive over the "red" power zone?

[a64pilot]

In my opinion 15 to 20 min of driving should have the car as warm as it will get, but without instrumentation we are really just assuming it's not warm because of how EV mode behaves, correct? So it may be warm, but something else causing EV mode to act up?

[bwilson4web]

Originally Posted by a64pilot

In my opinion 15 to 20 min of driving should have the car as warm as it will get, but without instrumentation we are really just assuming it's not warm because of how EV mode behaves, correct? So it may be warm, but something else causing EV mode to act up?

Testing with the 1.5L Prius, an engine that is about 5 lbs lighter than the 1.8L, shows the coolant warm-up takes about 300-360 seconds (5-6 minutes):


However, the real warm-up has to include the transaxle. Again, from the 1.5L Prius:

Also:


Also,


A lot of folks don't realize that the transaxle efficiency is very much dependent upon temperature of the lubricant:


So it is not enough just to get the engine to operating temperature but the transaxle too. Worse, the transaxle does not have ready access to the surplus exhaust heat ... although I have some ideas.

FYI, tires also have a warm-up, which is what formula 1 crews also do.

One more trick is to cut through the neighborhood in the morning. What I do is get the car rolling and while still applying power, shift it into "N". This prevents drawing any traction battery yet leaves the engine running in an idle mode. Measurements with my 1.5L Prius revealed that during the warm-up phase, idle in "D" consumes more fuel than idle in "N." So by putting the car in "N" with the engine running in idle, our ZVW30 should continue to warm-up but with the minimum fuel burn and only the overhead load on the traction battery.

I've started to make measurements and will hopefully have some data soon to share.

Bob Wilson

[a64pilot]

Maybe idleing in D uses more fuel because your charging the traction battery? So it may not be wasted fuel? Yes there are of course efficiency losses, and maybe the small charging load will shorten warm up time?

[bwilson4web]

Originally Posted by a64pilot

Maybe idleing in D uses more fuel because your charging the traction battery? So it may not be wasted fuel? Yes there are of course efficiency losses, and maybe the small charging load will shorten warm up time?

Ken@Japan had some data suggesting the NHW20 would run for about 100 seconds when started in the morning. But this is an area where we could use some data.

Bob Wilson