A Precaution for Prime Owners

are you sure it wasn't the fcev?

 

Is there even a hydrogen station near you?

Water is one of the by products of combustion, and the higher thermal efficiency of the engine means less heat is transferring to the exhaust system. This leads to more water condensing out in the tailpipe than leaving as a vapor. Condensing boilers and water heaters need a fan to keep the exhaust gases flowing out the chimney, because the gases have slowed down too much from the cooling.

 

That's no different than any other vehicle on the road. Think about how many short trips traditional vehicles take that don't hit full warm-up. The advantage with Prime is it warms up faster, so it clears out the moisture faster since that heat is needed for emission cleansing.

 

The Mirai is available out east?

 

Yup, I have seen this on the tail pipe of dozens of other vehicles. Why would this be worse on the Prime or any other vehicles with a combustion engine?

 

i had heard that they were going to build some filling stations around hereabout it probably never happened.
one thing we know for sure, you can't drive it across country.

 

I've seen 3 of them out here in the north bay. The nearest filling stations are 20 miles away in 2 directions .

Careful planning required.

 

The concern from the one mentioning is likely the fact that with the EV miles, the water could be sitting in the tailpipe longer than any car that fires up the ICE every trip.

I also add that a 40% thermally efficient ICE being running run at that as much as possible means that there is only 60% heat going to the engine block, catalytic convertor, and muffler as oppose to the 70% to 80% a non-hybrid would be throwing off.

 

it's possible that they were in warm-up cycle prior to getting on the freeway, especially if it's their normal route they probably switch from EV to HV as they get closer to the freeway. Having plenty of EV the gas engine would be at low RPM during warmup, which I think can build up condensation until the exhaust system gets hot?

Then they reached the on-ramp and gave it hard acceleration causing RPM (and resulting gas pressure) to spike, combined with possibly a slight uphill slope, and out comes the water.

I think ambient temperature and humidity also comes in play. Looks like you are having nice weather, but cool in the mornings. If you remember what day and approximate time of day it was you can check the temperature and humidity here:

Past Weather in Nashua, New Hampshire, USA — Yesterday or Further Back

 

i wonder if that's one reason the pip ice runs every 124 miles. toyota might have to go back to the drawing board if they start seeing issues from engines hardly ever running. but it will take years for them to start cropping up.

 

Understood, if in fact Prime's are collecting more condensation in the exhaust than regular cars (and hybrids). Worth investigating, but I was suggesting another theory to explain what you observed in that one incident which might be different than the normal overnight condensation that any car experiences.

Obviously unlike Prime, a regular car will be running ICE first thing in the morning which will clear it out. But even so that means that the car sat for probably twelve hours or more with condensation in the exhaust. Even worse for a car that is not driven daily, like a weekend car.

I would think only a small percentage of Prime owners don't use ICE every day. Those who don't, hopefully normal acceleration is enough to move some of the water out of the tailpipe, but if some remains then I suppose it's possible that those owners may wind up with exhaust leaks or other problems at say 100,000 miles instead of 200,000, just as a WAG. If that is the case maybe owners with short commutes should be advised to run HV for a few miles at least once a week or something.

But again my theory for the large amount of water that you observed in that one incident could have been the result of warm-up cycle.

As far as I know sloshing water sounds would normally be caused by air in the cooling system. Whether water in the exhaust can be heard I don't know.

Unfortunately it's not easy for a Prime owner to observe water coming out of the tailpipe unless someone is following them, making this harder to investigate. But I agree it is worth thinking about.

 

Then perhaps propose a way to quantify what you observed?

Bob Wilson

 

at least a couple of cups, would be 16oz minimum.

 

How does that compare to what normally comes out of a tailpipe when it is dripping? Hard to quantify, you glance at a tailpipe next to or in front of you and notice that it is dripping, but you don't know how much dripped out before you started watching, or how much will come out after you stop watching (or the light turns green). In the incident observed by the OP it all came out at once as the car made a hard acceleration. Then again we don't know if it was all of it, but assuming it was being pushed out by acceleration and/or gas pressure it seems a good chance that all or most of it came out at once, which would appear more dramatic then a gradual dripping at a stoplight.

Either way it does lead to a question of how condensation may work differently in a plug-in hybrid.