What's optimal "warm-up" time before turning on the fan?

I don't understand this question. in Auto, the prius doesn't push air through the vents until it can deliver hot air. So I guess the question is when do you get cold?

 

I think I understand. YOu want to know how long the ICE has been running before you blast the heat?

 

your MPG is still going to "plummet" whenever you need heat. And the only way to get heat in a PIP is when ICE is running. EV doesn't supply any heat in a PIP except for the seat heaters.

 

I think i know what you're asking. In most cars (including the Prius, someone correct me if i'm wrong), heat is "drawn" from the engine, simplistically speaking. So if you turn on the car and immediately hit the heater, bam... mpg plummets as the engine continously runs (even when you are stopped) to warm-up the engine. To answer your question, there's no simple answer. I think it depends on how many minutes the ICE has been running... I'd say at least 10 minutes of cumulative ICE. So that could be 30 minutes (20 on EV + 10 on ICE) or it could really be 10 minutes (e.g. if your commute is uphill for the entire first 10 minutes, no way in hell you're running EV uphill...unless you do 1mph LOL).

 

I don't think there's any way to definitively determine the # of minutes. I think one is best off using something (e.g. Scangauge II, Torque app for Android, etc.) to monitor coolant temperature (FWT on ScanGauge).

 

Yeah, that is probably true. For those without any monitoring tools, we have to give them a guess though you're right, really the right # of minutes will vary so much on weather and driving styles.

 

It absolutely will vary and can vary a lot. Climbing uphill at slow speeds in warm weather will heat up the engine pretty quick. Driving at highway speeds in cold weather doesn't seem to.

I've seen FWT on my Gen 2 generally higher in stop/go, city traffic than highway.

 

I monitor the ICE coolant temp with the SGII or either wait until I know I am hitting a spot where the ICE will be running continuously before I raise the cabin temp. It is disheartening to be sitting at a stop and watching the mpg fall as the ICE continues to run to warm the cabin.

I ususally lower the temp setpoint to 66 while waiting for the ICE coolant to warm up. Once it is either warm or I hit a spot where I know the ICE will continue to run then raise it to 70 or 72.

 

I don't turn the heat on until coolant temp is 150F & don't notice a significant hit. The PiP has the same ICE so...

 

It may help to be in Eco mode to lower the threshold in which the ICE will run to provide cabin heat. See my note at Why mileage gets worse in winter | PriusChat.

 

see post #11

 

the ice doesn't warm up in ev mode if you don't turn the heat on.

 

correct

 

so if you're trying to get the most out of ev mode, how long do you have to wait before turning on the heat?