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Discussion Starter #1
We just leased a 2004 Prius and I have one problem and a question.

We live in Las Vegas and it's hot. After having the car in the sun all day long my wife got in the car and cranked up the AC and started to drive home. The drive is stop and go and mistly uphill. She complained the last two days about very sluggish performance. Left it with the dealer today and they could not duplicate the problem.

One thing that I have found is the batter will loose multiple bars overnight. Is this normal?

As my wife normally drives the car I don't know the state of the battery when she left yesterday. Assuming the batter was discharged would this cuase the performance issue we had?

Thanks

Larry
 

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If the battery is losing noticable charge overnight, something is wrong. Is the key being left in? Is the car being left on? Other than this, I can't see why the HV battery would lose power.
 

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Note that when the car first starts up it protects the ICE until it's warm by running mostly on battery power. If you look at the battery display immediately upon pressing the Power switch it should be the same as you left it the last time you shut it off, and if it's not, then something is wrong.

However, it will be drawing mostly battery power for the first minute or two of driving, and if you wait that long to look at the display, it will be lower. Even just starting the ICE draws power from the HV battery and can drop it one bar if it was on the cusp to begin with. And if you back the car out, that's 100% battery power. And slightly uphill driving will draw it down even more. This would be normal. Of course, if the battery gets too low, the ICE will put out more power as needed to re-charge it.

Check the SOC when you shut off the car, and then again before the ICE starts and before you have begun to drive it.
 

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P.S. I just re-read your post. Sluggish performance is not normal. But a low battery should not cause that. But there could be an underlying problem that is both draining the battery and causing sluggish performance.
 

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Discussion Starter #5
Daniel,

But if the battery goes to zero bars wouldn't the performance then be bad as the your relying just on the engine and also trying to recharge?

Anyways thanks everyone for the information that the battery should not change levels when it is off.

Larry
 

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lrodis said:
But if the battery goes to zero bars wouldn't the performance then be bad as the your relying just on the engine and also trying to recharge?
Is this actually the case? Does your battery go to zero bars? I have done my best to get my battery to zero bars, going at 85 mph up a long steep hill in a mountain range, but it would only go as low as one red bar.

I would be interested to know if yours does go to zero bars, and also, any of the other symptoms it is showing.
 

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Just walking away from the car without pushing the power button will leave it on, but in that case if it is operating normally the engine will start as needed to keep the traction battery (the thing whose state of charge is displayed by the bars) charged up. Of course you should NOT leave it on; this wastes gas and fills the garage with exhaust.

By accidently pushing the power button with your foot off the brake you could put the car into the IG_ON state, in which case the engine will not run and the traction battery can discharge. When you want to power down the car push the power button ONCE and hold it for one second; you should see all indicators go off, except that the engine immobilizer indicator (a small red outline of a car with the silhouette of a key inside it) will flash every 30 seconds or so. Stabbing at the button as though it might bite you is a recipe for error :_>
 

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I was under the impression that the charge never got to zero bars- that's the story my dealer gave me. I've never seen mine go that low, and I (unfortunately) spend all too much time in traffic, where it routinely goes quite low. I thought the ICE automatically took over at 1-2 bars.

Definately sounds like something is going wrong there..

-M.Scopes
 

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Under some conditions (e.g. mountains) the battery can discharge to the point where the car will no longer draw from it. This is not actually zero charge. I have read figures of 25% and 40%, so I don't know the correct number, but to enhance battery life, the minimum allowed SOC is well above zero. Zero bars is this "minimum allowed" charge, rather than empty; and 8 bars is something like 80% of battery capacity (for the same reason).

At that point, as you suggest, the car is operating on the ICE alone. The ICE has 76 hp, which is 9 hp more than my old Civic had. You have less punch then, but the car still has plenty of power, and people have reported driving over the Rockies and never falling behind the flow of traffic, and even passing many other struggling cars.

So the answer is, no, it should not seem "sluggish" unless maybe you are used to driving a muscle car.
 

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Don't know whether this helps or not, but I recently was home for about a week and didn't do any driving at all. As best I can remember, I had 6 bars when I last parked it, but after about a week it seemed to be at 3-4 bars when I next started it up. It charged up fine on its own during the first 10-15 minutes of normal driving, and is otherwise not "mysteriously" dropping charge over just one night.
 

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Discussion Starter #12
re: Power/battery Issue on 2004 Prius - Update

When I got in the car to take it to the dealer yester I was able to get it to zero bars for a half second and then it charged up. The dealer was unable to get the issue to occur and overnight with them the battery level did not drop.

I had the car today with no issues.

I'll keep people posted as I understand more. BUt thanks to everyone for the feedback.
 

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I also live in Vegas (when the temps are lower). I have to remind myself that the altitude is 2300', and the temps are at the point where they do not go below 100F.

That might account for the sluggish performance. The temp affects the batt performance too.
 

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We just left Las Vegas yesterday and had no problems going back to Los Angeles, the car had plenty of power and the A/C was needed the whole way. We did remember with our Smart Key to use the turn off button so that the car is not sending out signals to see if you are around. The manual recommends turning off the Smart Key if the car is going to be sitting for a while so as not to use the battery. The trick of course was to remember to turn the Smart Key system back on when we started using the car again.
 

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Nick King said:
We just left Las Vegas yesterday and had no problems going back to Los Angeles, the car had plenty of power and the A/C was needed the whole way. We did remember with our Smart Key to use the turn off button so that the car is not sending out signals to see if you are around. The manual recommends turning off the Smart Key if the car is going to be sitting for a while so as not to use the battery. The trick of course was to remember to turn the Smart Key system back on when we started using the car again.
Just to note, that's two different batteries... The hybrid traction battery for driving around and powering the AC on a 2004, and the little 12v accessory battery that powers the SE&SS system (and powers the car's computers, alarm if equipped, radio, etc.)
 

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northbend said:
Does the battery indicator graph ever fill completely up? The most I've ever seen mine go is all green minus one.
Thanks....
Yes, on long a descent it might, but it won't stay full very long.

Drive happy,
Moo :)
 
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