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Discussion Starter · #1 ·
My 2004 Prius (55K miles) recently developed a problem the dealer can't diagnose. Gas mileage (highway) has dropped off 15% and when the battery meter indicates two bars, it lags when accelerating from a stop. I've noticed that once the engine is warmed up and I park the car but leave it on, the meter runs down from six or seven bars to two bars in less than five minutes! I checked a friend's Prius and the meter didn't drop at all while I waited seven minutes. There are other abnormal indications but anyone out there notice the time it takes to discharge while parked?
 

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Are there any wild swings in the SOC when you're actually driving or does the battery seem to behave normally under those conditions.

Are you running AC when parked? That can drain the battery pretty quickly.

In the very few cases of traction batteries requiring replacement the initial symptoms seemed to be somewhat similar to what you're describing, but most noted pretty dramatic swings in the HV SOC during driving as well.
 

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efusco said:
Are you running AC when parked? That can drain the battery pretty quickly.
It can be more than pretty quickly. Even here in Northern CA (not the hottest part of the world), when I leave work in the afternoon and the car has been sitting in the sun. My battery goes from nearly full to needing the ICE to come on for charging while I'm sitting at the first stoplight.
 

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Discussion Starter · #5 ·
I did the procedure where I drove and parked the car eight times - each time all the electrics were off (a/c, fan, lights, radio.) Temps were about 80 degrees. Since there's no load on the battery, it shouldn't discharge so rapidly. Occasionally while driving, it will go from two bars to seven bars in a minute, also go from seven to two bars in a minute. I wouldn't think any type of rechargeable battery would do so. I drive in the flat terrain of SE Michigan.
 

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PLombard said:
I did the procedure where I drove and parked the car eight times - each time all the electrics were off (a/c, fan, lights, radio.) Temps were about 80 degrees. Since there's no load on the battery, it shouldn't discharge so rapidly. Occasionally while driving, it will go from two bars to seven bars in a minute, also go from seven to two bars in a minute. I wouldn't think any type of rechargeable battery would do so. I drive in the flat terrain of SE Michigan.
That is worrisome and clearly deserves a trip to the dealer soon....CEL or not.
 

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Discussion Starter · #8 ·
Latest from Toyota

I rec'd a call from Toyota in California. The woman who called said the battery bars are determined by driving style, not by the amount of charge in the battery - as if you drove like a NASCAR driver or a grandpa. (That doesn't make sense to me - I thought if person A parked w/ 5 bars and person B parked w/ 5 bars it would indicate the same approximate level of charge.) I asked her if Toyota would test a number of cars to rate how quickly the battery discharges in park and she replied that they would all be dependent upon how the driver drove prior to parking so to Toyota, it is a nonsequiter.
Anybody belive this from Toyota? Anybody try timing how long it takes to discharge the battery while in Park?
 

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Re: Latest from Toyota

PLombard said:
I rec'd a call from Toyota in California. The woman who called said the battery bars are determined by driving style, not by the amount of charge in the battery - as if you drove like a NASCAR driver or a grandpa. (That doesn't make sense to me - I thought if person A parked w/ 5 bars and person B parked w/ 5 bars it would indicate the same approximate level of charge.) I asked her if Toyota would test a number of cars to rate how quickly the battery discharges in park and she replied that they would all be dependent upon how the driver drove prior to parking so to Toyota, it is a nonsequiter.
Anybody belive this from Toyota? Anybody try timing how long it takes to discharge the battery while in Park?
That is not an accurate description of how the bars on the Energy screen work....it does sound like a so-so explaination of how the Consumption screen bars work though.
 

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Ask to speak with someone with better knowledge of the Prius. That doesn't follow New Car Features or the repair manual. Granted that neither is specific on what each bar means.

One thing to note though, the bars are not linear, and they have hysteresis. Bar 6 has the widest range of SOC, and the level needed to go up from one bar to the next is higher than the level needed to go back down. Temp also affects battery capacity, thus will affect how much energy you can get out of the battery from one level to another.
 

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DanMan32 said:
Did they ever come out with a PC version of this software? Seems silly to limit it to a PDA that not everyone would have.
http://www.privatenrg.com/PCprog.htm
Dan, shoot Wayne an e-mail, a tech oriented enthusiast like yourself he might be willing to send a beta of.
 

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DanMan32 said:
He really needs to fix up his website. All that link shows is a bunch of screenshots, and I don't find anything on his main page linking to it.
How did you find it?
I agree, his main page is not much more than an index page.
At the bottom of the list of links at the to of the main page there's a link/line that says "Please Build a Windows PC version"...and then it links to that page w/ the screen shots.

Your best bet is to e-mail him for details and to ask for a beta trial...his e-mail is at the bottom of the page.
 
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