Dramatic Loss of Power/Performance in My Prius

<div class='quotetop'>QUOTE(jw_teacher @ Aug 1 2006, 04:12 PM) [snapback]295878[/snapback]</div>

Sorry, no suggestions, but you should be concerned. I've driven in well over 100 degree temp and the power feels like it always does. I'd take it in as soon as you can.

 

the temperature in the battery compartment does determine the amount of power that can be extracted from the battery... as it gets hotter, the battery becomes less efficient. It's possible that, sitting in the sun, the car got extremely hot, including the battery compartment, and needed to cool down before it could provide max power (thus the fans straining). having the windows open instead of using AC could have delayed battery cooling, as the air temperature in the cabin wasn't cooling quickly. I'd recomend trying a comparison in similar situations of running the AC for a few minutes first to help rapidly cool the cabin temperature and see if the problem goes away. if it still has a problem with a relatively cool cabin, then i'd definately be worried and take it to the dealer.

You could also always get a can-view to see exactly whats going on with the batteries and the power and such.

Darn EFusco, you beat me to it! posted almost simultaneously!

 

<div class='quotetop'>QUOTE(San_Carlos_Jeff @ Aug 1 2006, 04:14 PM) [snapback]295882[/snapback]</div>

I wouldn't. That's sounds exactly like my 102 F degree experience. The system simply went into battery-pack protective mode. The heat most definitely was to blame. All was fine after that single incident.

 

From the description, it almost sounds like the "traction control" is kicking in. Is there any indication on the dash? Maybe there's a bad sensor or something.

 

This is why the battery vent is inside the cabin. The battery needs about the same temperature range that people find comfortable. I don't think that the owner's manual makes any mention of this, which is unfortunate. Imagine how many owners might be seasonally sweating and freezing under the mistaken impression that they are helping their fuel economy.

 

I can reproduce this condition.

A. Drive car to work, park in sun.
B. Go out for late lunch, about 1.5 miles away, around 2:30 pm.
C. Park car in sun again.
D. Leave for home a little early (say 5:00 pm).
E. Car will run in sluggish mode with only one bar on the battery. Vent fan is on in the backseat on high, you can't miss the sound.


The key here is the late afternoon hot soak. The batteries are very hot from my lunch jaunt and had no opportunity to cool since the ambient air in the car is up over 120.

Going to lunch earlier helps, so does parking in the shade. (I already have tinted glass and a sunshade)!

You may also be able to prevent this by letting the vehicle run for a few minutes before driving off. (I know, crazy, huh?).

Nate

 

did you leave the parking brake engaged ? if not, the take it to your Authorized Toyota Dealer ASAP

 

This is a rather curious thing to me, as I've never had it happen with my Prius. Mine's an 05 that has sat out in the Phoenix sun all day at temps around 118F. I have never had it fail to start moving energeticly within seconds of start-up, even when it's had all day to bake. I do use the air-conditioner all the time, but that dosn't seem like it would have any real effect here. I'm usually moving before the air coming from the vents is even cold. It can't possibly have provided enough cool air to the battery to have had any effect by then. It just seems to me that there is something more going on here if a 100F battery exibits these symptoms and a 118F battery does not.

 

The battery and associated electronics make their own heat while in use and will get a lot hotter than 120'F unless cooled. The original poster noted that the loss-of-power happened while in motion, which would have given the battery system time to heat itself up while sucking uncooled cabin air. Running the A/C continuously as you and I do never allows that self-heating to get out of hand.

 

<div class='quotetop'>QUOTE(richard schumacher @ Aug 2 2006, 02:29 PM) [snapback]296440[/snapback]</div>

Okay, I had read the op to mean the symptoms happened right away. If he ment it happened after a while driving, then it makes more sense. A minute or two of low speed (high battery use) driving without the AC on would definetly be much harder on the battery then the same drive with the AC on. Well, you know what they say about assuming. Sorry.

 

jw teacher, do you put the car into a hot soak like I did?

(just curious)

Nate

 

<div class='quotetop'>QUOTE(jw_teacher @ Aug 1 2006, 05:12 PM) [snapback]295878[/snapback]</div>

Wow, it's a 100+ and no air on to save gas -- I couldn't get much further than that in the post. Really no offense meant at all...but why? I'm new to the Prius world but from what I've able to discern the mileage differential with the air on is pretty marginal....and I'm sure even more so if you have the temp set high enough to mostly just lower the humidity - I leave my home and prious on 80. Of course, here in mid GA the humidity may be a lot higher than your area -- I'm a pretty fit athlete but it has been brutal here.

 

This is making sense, the pieces of the puzzle are fitting!

It has been very hot here lately and my mileage has been a bit off. Studying the battery and it has seemed a bit low. Often my commute is less than 15 minutes, so that's not enough time to cool down the car.

see my post in fuel economy:

http://priuschat.com/mileage-droppingand33...d33-t22670.html

 

<div class='quotetop'>QUOTE(jw_teacher @ Aug 3 2006, 10:54 AM) [snapback]296944[/snapback]</div>

Ah ha! Another place for improvement. When you get in the car open ALL the windows ALL the way. The hot air will exhaust, and the car will cool, much more quickly. This is especially true if you use A/C to cool the car. It isn't going to be putting out cold enough air to bring the inside down from 170F to the ambient 115F anywhere near as fast as straight replacement of the air.

Also, unless it is horribly crime ridden in your area, leave the windows open 1/2" during the day. It helps a lot.