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Discussion Starter · #1 ·
I have an 03 model prius that's travelled 46000km.Recently I noticed that my battery state of charge indicator display is erratic.The bars will change from full green to pink within a driving distance of 200 metres and jump back up to 5 bars blue.This happens constantly especially under acceleration and on a very hot day.Has anybody encountered similar problems?
 

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BSOC not AOK

As the battery display changed color I suppose this is the 2004 model, even if purchased in 2003. I have heard of similar situation. You must let a qualified Prius tech check for battery trouble codes. I don't want to jinx the situation, but a replacement high voltage battery and/or controlling computer are possibilities. Will be covered by warranty. Good luck.

DAS
 

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Discussion Starter · #3 ·
Took my vehicle to a dealer this morning.Tech checked diagnostic codes of hybrid control and hv battery ecu's.No codes logged in the system.Have left vehicle with dealer for further diagnosis.Will keep you posted.
 

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I have theorized that temperature fluctuations can change the SOC displayed, but not from full green to pink. Maybe a few bars from an airconditioned cabin of 72 degrees to a balmy hot 90, or a chilly 50 degrees. I theorize this as I believe the relative SOC is dependent on battery temperature just as air relative humidity can change at different temperatures for the same absolute moisture in the air.
 

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Hi Rabbit,

That sounds like an intermitant connection. Hope its in the SOC meter connection to the battery, or the SOC meter circuits. If its in the battery, could be expensive. One of the things the newer Prii have is welded battery connections to improve interconnection resistance. Could be a busted weld.
 

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I also experienced the battery go from full green to 2 'pink' bars by driving up a freeway onramp at 102 degree weather. Dealership kept telling me this was normal. I can't believe that. I never read about this in the owner's manual. Got better with cooler weather. I may move to a cooler area.
 

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Discussion Starter · #8 ·
Being a NHW20 series prius it only had the ECU upgrade.From what I've been told battery recalls relate to the NHW11 series. Anyway, picked my car up from the dealer today and I have been told that my battery SOC concern has been rectified for the moment but they believe that the fault will reccur.I spoke to the head mechanic who took the time to explain to me what he has found. He took a couple of snapshots of the vehicle's hybrid control and hv battery data list using their intelligent tester.He was kind enough to give me a copy of that data.He compared that data to another 20 series prius of roughly the same mileage and found one item on the hv battery data that was out of specification.

The item in question is called the Delta state of charge and on my vehicle it indicates a reading of 81%, however on the 'donor' vehicle it reads 0%.
By disconnecting the auxillary 12V battery he was able to reset the memory of the hv battery ecu and the Delta soc reset back to 0%.He road tested the vehicle and found the system operation was normal.
I was told the data would be sent for analysis to the Toyota technical centre to advise on a possible repair method as the mechanic was unable to find information of the purpose of the Delta soc.

Well after all that mindblowing information,I'm happy to report my vehicle
is once again as good as new,for now at least. Cheers!
 

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This is useful, but only a start. There is still no root cause identified.

Is that value the result of the mysterious periodic "SOC calibration" step we have seen posted about here? If so, and if there is a cell bad, would this "SOC Calibration" result in an incorrect value?

If so, the next step is to identify what can throw the SOC Cal off. Can a single bad cell do it? How about a bad weld? Can the fault be isolated? Is the solution a new battery regardless? If so, then you should start shopping fora battery on ebay or through dealers or junkyards.

A good start, but they need to take it to the next logical step.
 

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The closest thing that I can think of:

http://autos.groups.yahoo.com/group/toy ... 023-04.pdf
US TSB EG023-04
June 28, 2004, Revised July 12, 2004, 2004 Prius. M.I.L. "On" HV Battery DTCs P3000, P3056, and/or other DTCs. Battery cell votages may show zero charge, but car runs normally. Fix: replace Floor Wiring Harness No. 3.

But that would have error codes and warning lights on your dash...

Do you have any other display oddities? Again, it would probably show no charge on the battery icon at all, but it could be the NHW20's version of Newarkitis. Is the touch screen slow to respond? Is the outside temperature display missing, or no arrows seen on the Energy Monitor? Do you have wierd times of 0 l/km or 100MPG bars on your Consumption screen, even though your engine has been running while driving? Do you get phantom audio, or "check connection" errors for the climate control or navigation buttons? Yet another TSB for that on some 2004 Prius like yours, and it has been happening internationally...
 

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I had the same issue, and they performed the TSB Michelle referenced.

I did have a light show on the dash, but there were also other codes at the time that were treated separately.

I'd mention that TSB to the Tech.
 

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Hobbit said:
Anyone know offhand exactly what "delta state of charge"
actually means??
.
_H*
"Delta" (the greek alphabet) is used in science and engineering talk to refer to "change" - usually large changes. So, "delta state of charge" refers to the change in state of charge. e.g. if the SOC went from 10% to 30%, the delta is 20%. When the changes are very very small, minute, it is usually represented by the greek alphabet Epsilon.
 

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yauman said:
Hobbit said:
Anyone know offhand exactly what "delta state of charge"
actually means??
.
_H*
"Delta" (the greek alphabet) is used in science and engineering talk to refer to "change" - usually large changes. So, "delta state of charge" refers to the change in state of charge. e.g. if the SOC went from 10% to 30%, the delta is 20%. When the changes are very very small, minute, it is usually represented by the greek alphabet Epsilon.
My understanding is some what different.
Toyota Tech Manual says it's unevenness of battery capacity.
My bet is unevenness of SOC between pair of modules.

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