Warm up time?

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

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

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

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

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

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?

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

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

I has ASSumed that the running time would be a variable based on temp of the engine at start up and that it would run until some value was reached temp wise. Apparently that may not be the case?

Here's how I determine it. Normally, after the engine has warmed up, I can take my foot off the accelerator for just a second and see the mileage bar zoom up to 100. Then I can gently press on the accelerator to keep going while the bar stays at 100.

When the car ICE is heating up, if I lift my foot from the accelerator, the mileage bar does not shoot up. That's how I know the ICE hasn't fully heated up yet. Once that mileage bar shoots up, the ICE has reached its temperature.

You guys out there with gauges might be able to nail it down a little more precisely, but I think this method gives a fairly good indication of when the car has kicked into full hybrid mode.

I have found that it takes 5 minuter or so to "warm up" even if the car is warm. For example after driving for a few hours at high speed we stop and switch drivers. If we turn the car off (which we nmormally do) we have noticed that it takes some time before you can go into the EV mode and that the first few miles provide less miles per gallon. I do not know why this is the case.

Stan

I'm a little confused about this as well....
on the one hand, the ICE runs most efficiently in the 75%-100% range of the HSI
on the other hand, its not warmed up yet, so maybe traction would be more efficient than a cold ICE?

yep, Tom is right, Pri wont warm up. i start mine, it runs until water temp hits about 120º and then it stops. so, to warm up properly, you have to drive. the sooner you start driving, the sooner you will warm up to proper operating temps. usually about 2- 5 minutes depending on how you drive.

This goes against with what many has said so far but this was done in my previous CR-V, not the Prius.

I have tested different warm-up techniques for FE during frigid days (around 10F) in my very short commute at that time, which was 10 miles.

1) Left the car warming-up on neutral before leaving to work (idle)
2) Went thru a low speed route to allow warp-up gently when driving (no idle), then once warmed, drove normally.
3) Went to a highway very quickly with lots of acceleration and power to get it warmed faster (no idle).

Guess, which one would deliver better FE every time?

Number 3... Despite of what has been said here, but maybe it is different in the Prius.

as long as you are doing as little idling before driving as possible, you will be fine

That's where the controversy is. Many here suggested that idling is bad for warming up the Prius. My experiments with my previous CR-V also suggested that idling is indeed a very poor technique for warming up. So, I guess the question becomes, which one works better to increase FE in the new Prius, driving gently or a quick high-power warm up?

dont think either makes a real difference. it really all depends on where you are going. if i was in a position that i needed to hop on the freeway and it was a few blocks away, i would not do a leisurely cruise around the block a few times first.

as it stands now, the speed limit is 25-40 mph with a ton of lights that can be timed relatively easy, so i take off in the morning at what most would consider a slow pace, but only because racing between lights will kill your mileage and there is already a bunch of people doing that, which is good because i leave it up to them to trigger the sensor pads.

Then there are old school people like me that contend that an engine should be warmed before being put under loads and allowed to cool after being loaded for max life of the engine. I've tried driving off right after the "ready " light is illuminated and have tried allowing it to sit in the garage and run until it shuts down before driving off. I have been able to detect no difference. I assume it's either the fuel used in the min. or two of running while sitting is so small, or maybe it's because if you drive off cold the traction battery is primarily what is being used and re-charging it is inefficient. Either way I can't quantify a difference
If you drive you Prius trying to maximize mileage, I doubt it accelerates the wear much if any driving away on a cold engine, so I guess it's a moot point?