Went to the mountains in our Prius

[jendbbay]

Well, we did it. We took the car on a family trip. We had assumed this would not be possible, since our trips are all camping trips and we have way too much stuff to fit into that tiny car. Wrong! It all fit easily -- more easily than it fits into our Honda Accord LX, 1998. The only concession I made to the Prius is that I did not bring our large cooler. Instead, we had one small one and one even smaller one.

I found the Prius easy to pack, since I was not forced to bend over and thereby throw out my back -- always an annoying way to start a trip.

Our MPG was not terrific. We got around 44 to 46 for the entire trip. I had thought it would be close to infinite on the way down the mountain, but it really wasn't, and the trip had a lot of flat, hot miles during which we crossed the Central Valley and used AC.

Our normal MPG is around 52 these days, but we saw less than that during the winter. The car is fully broken in, and we did see improvement in MPG after 10K. We now have 16k on it.

Okay, the problem...

We were going up the mountain and the displayed outside temp was 94. We had the AC on with moderate force. We lost power and noticed that the battery display showed purple bars -- maybe only 2?

I was quite worried, I switched to the climate control display and noted that we were recirculating the air. I switched to the other choice to bring in fresh air. Immediately, the power came back. I told my husband that must have been the problem. He was quite perturbed with me for this idiotic theory. He claimed that you want recirculated air to make the car work less hard to cool it down. Okay, I admit that is a reasonable theory, but I had this feedback experience --switch to fresh, problem went away.

So, if I was wrong, what was going on? If I was right, why/how could my illogical theory be right?

We did not have the problem again, though we saw many times, while up at 8700 feet, when the battery level was down to the two last purple pips. We never lost power again, however, and the car was able to recharge when it felt the circumstances were right to do so. I'm not exactly sure why it would get so close to using up the charge, but other than the one loss of power episode while climbing mountain, we had no other ill effects. Once we returned home, emptied car out, and husband resumed his normal commute with it, the MPG returned to the 52 or 53 that he normally gets.

Many thanks for any ideas you may have.
jen

[Miss_Taz]

There is absolutely no problem with going down to 2 pink bars... It happens all the time, even in normal everyday flat traffic. That is completely within the normal range of operation for the Prius, so you needn't worry about that! It won't let the car go any lower than what it's designed for...

As for the recirc/fresh thing, that sounds very odd to me also... Hopefully one of the more techie types can theorize on the behavior you saw...

-Vikki

[qwagmire]

Actually you may have helped. Sometimes climbing mountains the reduced air pressure messes up the climate control system. Cycling through different climate settings undoes the problem.

Im new to the Prius, but in one of my trucks had "issues" on I-70 going from Utah to Colorado and when I turned off the AC you could hear the vacuum going away. I turned the AC right back on and no more issues.

[priusincc]

<div class='quotetop'>QUOTE(jendbbay @ Jul 31 2007, 05:27 PM) [snapback]488393[/snapback]</div>

Okay, the problem...

We were going up the mountain and the displayed outside temp was 94. We had the AC on with moderate force. We lost power and noticed that the battery display showed purple bars -- maybe only 2?

I was quite worried, I switched to the climate control display and noted that we were recirculating the air. I switched to the other choice to bring in fresh air. Immediately, the power came back. I told my husband that must have been the problem. He was quite perturbed with me for this idiotic theory. He claimed that you want recirculated air to make the car work less hard to cool it down. Okay, I admit that is a reasonable theory, but I had this feedback experience --switch to fresh, problem went away.

[/b]

When you switched to "fresh" and the power came back did you still have the two purple bars? Could you have turned the A/C off? Also, how many people in the car?
I was at same altitude with four adults and had very little power up a longer grade. I'm trying to get some correlation between power and air conditioner mode. On the surface, there doesn't seem to be any.

[donee]

Hi Jendbbay,

My guess is that with multiple people in the car, and recirc on, is that the humidity in the air built up. And the car was trying to use the AC as a dehumifier, by running the condensor very cold. The extra AC electricty load pulled down the battery. It appears (appears only) that turning off the Recirc in this situation resulted in the AC being used to cool the outdoor air, which seems to require less AC electric load than dehumidifying the interior air. Which might be the case in the mountains, as the outdoor air is less dense, and much drier than near sea level.

Again, this is only a guess.

[Sarge]

<div class='quotetop'>QUOTE(jendbbay @ Jul 31 2007, 08:27 PM) [snapback]488393[/snapback]</div>

We were going up the mountain and the displayed outside temp was 94. We had the AC on with moderate force. We lost power and noticed that the battery display showed purple bars -- maybe only 2?
[/b]

Hi Jen,

I assume by "loss of power" you mean the acceleration was a lot weaker than normal...?

As you know, the Prius uses the high-torque electric motor to provide the low-speed acceleration, since the engine (ICE) has very little torque. If your battery is low, then the car has little to power the electric motor, and the result is much weaker acceleration.

Climbing hills draws extra power, as does the A/C. I believe the recirc draws even more (the dealer always uses Max A/C with recirc to drain the battery for testing ), though perhaps someone with more technical insight can confirm that.

It simply sounds like you reached a condition where the battery was near empty and you had temporary weak acceleration until either the load was reduced or battery charge was built.

Either way, it sounds like your Prius was operating exactly as designed, and I wouldn't worry about it.

[OlsonBW]

Note that my 2007 Prius Touring gets 8 to 10 mpg less when AC is on and the ICE (internal combusion engine - i.e. gas engine) is on.

[abq sfr]

Contributing factors:

1) Sounds like you had your poor Prius loaded down with stuff, hubby or wife and camping equip adding weight to what it had to pull up the hill.

2) Any gas engine (and person) will have less power at higher altitudes due to decreased air available. 8700 ft is pretty high.

Yes, the AC will pull your battery down to pink (purple), but like others said it won't hurt anything, the computer babies the battery. At pink the battery still has around 40% charge. Mine always goes pink at McWendy's drivethrough... Here if there are only 3 cars in front of you it will still take 15 minutes to get up to the window and the AC will pull the battery down. Then every time the car moves a little the ICE will come on. You will have less power when you hit the street because the battery is not providing much if any power, it's mostly up to the ICE. But it should recover within 5-10 minutes with normal driving. I hadn't heard the theory about AC recirc/fresh... with mine the computer decides which to use. When I first got this car I tried to adjust the AC and Heater... after a few weeks I gave up and just started leaving it on auto set points or turning it off because it seems to have a mind of its own. Forget turning off AC and going to just outside air with no AC (you gotta push about 6 buttons and lower the temp all the way), mine always blows warm anyway unless its below about 60 degrees. One of my few pet peaves with this car.

[Spoid]

<div class='quotetop'>QUOTE(OlsonBW @ Aug 1 2007, 12:18 PM) [snapback]488766[/snapback]</div>

Note that my 2007 Prius Touring gets 8 to 10 mpg less when AC is on and the ICE (internal combusion engine - i.e. gas engine) is on.
[/b]

What do you normally get? I'm in Las Vegas, and my 07 Touring went from 46 to 42 when I started running the AC full time, and I bet my AC has to work harder.

[jendbbay]

I am making a general reply to all 8 posters!

Thanks for your inputs all 8 of you. I had to rush out of here and was preoccupied all day with things and forgot that I had a question brewing here.

I actually ran into the problem on the way up the mountain when I was at about 5 thousand feet and going mostly uphill and running the AC on recirc. Switching to fresh immediately restored power andI never lost power again for the duration of the trip, even though I saw the pink 2 pips left on the battery a number of times. I'm voting for the humidity theory. That the three of us, particularly with my husband talking constantly about his programming issues, caused the AC to have to work harder.

I took avid note of above-mentioned fact that the method of choice for draining the batt involves use of recirc! I am thinking that it was under such load that the batt could no longer assist in powering the car.
By the way, we did not experience such high external temperatures for the remainder of the uphill climb as the temperatures higher up were down into the 80's and even high 70s.

I love our Prius and now consider it a completely viable trip car for the three of us and all our stuff. My husband drives 75 miles each week day, and during the regular school year, I add 10 to that plus about 20 on the weekend for about 21Kper year. At 3 per gallon, our crossover point is going to be in the 4th year of ownership, not the 10th as the articles were saying before we bought. And, of course, had we been able to hold off to purchase it until now, the crossover point when compared with the Honda Accord LX would be in the 2nd or 3rd year of ownership! It is not hard to see why the Prius was bought by more people in Silicone Valley last month than any other car.

jen