ICE stays on AFTER 25 miles of driving???

Air conditioning perhaps?

 

Turn off the defroster. You probably aren't using the heat but turn that off too.

Also, make sure you are doing a proper glide (barely using any battery, nor doing any regenerative braking) instead of doing what is commonly known as stealth, which is just driving under battery power. If the battery is low, the engine is on.

OK, also, it's not uncommon after I have done an extensive P&G session (100 MPG+ for >5 minutes), with very long glides, that the engine is cold enough it wants to warm up again.

 

How does the traction battery indicator look? Does it look constantly discharged? Perhaps below 50%? After driving 25 miles it should show 75% IF your driving on the interstate. Like one member said, heavy A/C usage (while not in ECO) could cause the engine to stay on if traction battery levels are low.

 

Are you sure you're in stage 4? Apologies if this is very basic for you, but if you're not sure what it is, check out http://priuschat.com/forums/gen-iii...-discussion/76501-gen3-warming-up-stages.html

 

Mike, after 25 miles of driving in Miami Florida in June? Surely its warmed up and in stage 4.

 

Hey GSW,

The "warmed up" part of my post popped up automatically from the link I provided, since it's the title of the thread - I didn't type that. I agree the car would be fully warmed up.

Since it's possible for the engine to be quite hot while still in stage 3, I'm wondering if he may not be in stage 4. Even though it seems unlikely, jnodarse now said his last bit of driving is through a local neighborhood, so it may be possible it's at speeds under 25 mph, where stage 3 would keep the engine on.

The AC also sounds like a very good suggestion, I would try that first, and the stage 4 thing as a later option. Let us know if you get it resolved, jnodarse.

 

I'm not sure on the 2010. But on the Gen-II Prius if the battery temperature gets too hot, it will stop allowing use of any all-electric drive. I would guess it is the same on the Gen-III. There are people out there who have hacked the battery fan to run all of the time in order to prevent the battery from getting that hot, allowing more stealth mode and EV mode driving during the Summer.

I think 25 miles was around the magic number for my 2008's battery to get too hot.

 

If you come to a stop does the ICE turn off? You said you had the A/C on the lowest setting? I'm pretty sure if you have it set to Max A/c the ICE will continue to run, just set it to like 70 or something like that.

 

Just a few thoughts:

Check to see if you have the HV battery vent blocked somehow

Perhaps you should borrow a Scanguage to see the ICE coolant temp. It perhaps may be a faulty temperature sensor.

Within 2 miles it is entirely possible for the car to drop back into Stage 3 if you are gliding enough and there are lights. What are morning temps and is the air slightly wet (drizzling, foggy, etc.)?

 

+1 to adric22; I've definitely had mine go easy on the battery and run the engine more when the battery gets hot. For me, this typically happens when going over mountains - so I drain the battery (on purpose) as I approach the top, then charge the battery fully on a nice downhill section, then drain it going back up, then charge it... It gets hot pretty quick when it's near full. It also can happen if the car is, for example, parked in the sun and very hot. And if there's something blocking the battery vent (either something covering the vent, or dust or small kids' toys or whatever clogging the ventilation behind the cover), that will make it worse.

You might consider running the air conditioning a bit stronger, to see if that helps. The battery is happiest at temperatures that are comfortable for people, too - say 70°F or so. (On the other hand, it also draws more power from the battery, but if you're just barely comfortable in the front seat with the vents pointed right at you, you can bet the battery is unhappy in the back seat.)

 

+1

Or maybe a faulty thermostat? Not sure what's in the Prius, but traditionally there's a thermo-mechanical thermostat. It's closed when the engine is cold, to bring it up to temp quickly, then opens to allow coolant to circulate to the radiator. If it's stuck open, you could be cooling too efficiently, especially when travelling at highway speeds.

Because the Prius lacks a engine temp gauge, you would need a Scangauage or something similar, to check coolant temp.

 

The main battery is just behind the rear seat and below the trunk. If you lift the removeable floor of the trunk and the cargo tray below it, you can see where the main battery is and also where the 12V battery is.

The intake vent for the battery ventilation is between the right rear seat and the door

 

That's where it is, on the right hand side in the non-folding portion of the cushion of the rear passenger seat.

Make sure if you have pets or whatever that it's not clogged with fur or dust.

I mean, really make sure that you don't have the defroster on. That includes the "Windshield and Feet" setting on the fan position selector. I only use "front" or "front and feet".

A good test to check engine temp is to see if you can go into EV mode when you are above 12 mph and below 24 mph.

 

The layer of carpetted floor directly over the main battery is a bit of bear to pull off, but it can be done. There's about 5 push-in fasteners, and one 10mm (socket size) bolt, the latter by the rear seat pillow. An automotive panel tool or two is needed. Some of the fasteners will likely pull out of the floor part in the process, but likely without damage.

If and when you do get it off, you can pull all those tough fasterners out (label and bag them). The remaining alignment pins and the 10mm bolt are ample to hold it down.

Once you've got that off, a bit more plastic ductwork removal and you can check the fan's condition.

 

I think the good test is the ability to use pure EV mode during your trip - maybe you will see same diagnostic message on display.
The scan for DTC codes can be usefull as well. if DTC memory is clean, the exact diagnostic wiill need experienced dealer's technician. who is familiar with exact car operational condidtions and able to diagnose the problem by reading the Techstream data.

 

Great suggestion on trying EV mode!

I was thinking to ask whether you're using ECO mode, or not; didn't see you specify that. ECO mode will minimize use of the compressor, and allow more EV-only operation.