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HV ECU vs. Hybrid Battery - Which is bad?

Discussion in 'Gen II Prius Care, Maintenance and Troubleshooting' started by simonman, Dec 28, 2011.

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  1. simonman

    simonman New Member

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    2007 Prius
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    I have a 2007 prius with 140,000 miles. Never had one thing go wrong with it.
    Recently, the Toyota dealer when replacing the tires "fixed" the hybrid cooling pump issue and flashed the computer (I am not sure why any software revision was involved). They did the fix without my consent or knowledge. Now, 2 weeks later, I have several warning icons on my dash. The dealer says I need a new battery for $3300. My question is, how do I really know if the battery is bad or if it is the HV ECU (charge controller)? The battery appears near dead in the morning but about 5 minutes down the road it will be charged up to the max for the duration of my drive. The car has a lack of power. Any help would be GREATLY appreciated. I was not able to find my answer in the forum anywhere.....
  2. 3prongpaul

    3prongpaul 6 Gen1s, 3 Gen2s

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    Tell them to flash the Battery ECU back to where it was. If they won't do it, call Toyota corporate and explain what happened after the dealer "upgraded" the computer. Try and get corporate to replace battery under warranty. If that doesn't solve your problem, get a good used battery for $600-$800. Not too hard to install for most mechanics and DIYers....and very safe to work on once you remove the orange service plug.
  3. JimboPalmer

    JimboPalmer Nadir of Wrongness

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  4. 3prongpaul

    3prongpaul 6 Gen1s, 3 Gen2s

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    At this point in time most lowish mileage Gen2 "junkyard batteries" are still very good, especially if the car was in a front end collision. Any 2004-2009 battery will work in your car. No need to have your Gen2 battery rebuilt.

    Your cheapest solution would be to source a used Gen2 battery yourself from AutoBeYours, AdoptAPart or similar then have someone locally install it.

    If you had a gen1 Prius (2001-2003), that would be a different story. For Gen1 prius you want a rebuilt battery or at least one with a decent warranty in case it doesn't work out...most junkyard Gen1 batteries are in fact junk.
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  5. seilerts

    seilerts Battery Curmudgeon

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    I'm not aware of any reflash available for '07. I'm not sure it is even possible to reflash the battery ECU. If you could scan and post a copy of the invoice, then we could comment further. What you describe has all the hallmarks of HV battery failure. You can try the "you serviced my car and messed up something" approach, but it will be very difficult. Yours has the combination of age and mileage for when failure becomes a possibility.

    If you can pull a battery from a fresh wreck, <6 months, it should just work.
  6. richard schumacher

    richard schumacher shortbus driver

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    It is common when replacing the pump to not get all the air out of the loop; the dealer who did mine needed to re-do it, and we've read of multiple cases here. It could very well be as simple as that causing the inverter to overheat. (Yeah, I know, it's winter, but if it's not getting any coolant...) Before spending thousands tell that dealer, or a different one, to try again. Given the "let us sell you a new battery" advice I'd lean toward a different dealer. But do it soon, because an un-cooled inverter can destroy itself.
  7. mehanson

    mehanson ElectroMechanical engineer

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    I have a gen 1 (purchased in April 2000) prius which just got the HV! warning and codes P3000 and P3006. In a static test of the battery at a dealer this Friday the blocks of cells were within 0.7V of each other (less than the 1.2V criterion). The diagnostic chart the tech was using indicated that the ECU needs replacing.
    I'm not convinced that we've tested it appropriately.
    I see that the ECU does control the flow of energy from the battery to the motor/generators, so perhaps it's not a connector issue. My first guess was to 'wiggle' the connectors (not high voltage, but control signals) that relate to the HV ECU. Often in computer systems it's the connectors that cause failures.
    Any thoughts?
  8. seilerts

    seilerts Battery Curmudgeon

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    1.2V is the most definitive, because it means for sure that a cell has gone bad. But 0.7V from high to low at rest is a very bad sign. .06V/cell is a huge difference in NiMH state of charge, as much as 50%. In normal conditions, the difference is 0.1V or less. Your ECU is fine, and your battery needs to be repaired or replaced. I do not recommend replacing a Gen 1 battery with another one from a junkyard. You need to look at ReInvolt.com or options along those lines.
  9. jdenenberg

    jdenenberg EE Professor

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    If it turns out that you need an HV battery ECU, I have one that I would be willing to sell.

    JeffD
  10. mehanson

    mehanson ElectroMechanical engineer

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    How did you end up with an extra ECU?

    But more to the original point, in Massachusetts the dealers say the hybrid system warrantee is for 150K miles and 10 years. I'm not sure about Michigan, but perhaps the repair is covered?

    I have a Gen 1, 2001 prius that is showing p3000 and p3006. I've not been satisfied with the Toyota dealer service department's diagnostic methods so far, but will work with them some more on it. In driving the car I'm wondering if the problem I'm seeing, which looks more like an ECU malfunction than a battery failure, might be due to corrosion on the ECU connectors that is garbling data occasionally. Any thoughts? In my experience as a mechanical engineer and computer systems designer it's often the connectors that cause system malfunctions. However, beyond resetting the connectors, I don't have a good strategy for checking this.
  11. jdenenberg

    jdenenberg EE Professor

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    When the HV battery failed in my 2004 Prius at 195,000 miles, I replaced it with a ReInVolt ($2000 installed). I was not required to send them my old battery, so I disassembled it and determined that only one module had a bad cell. After a little research I purchased some equipment, rebalanced the 27 good modules and have sold all of them (clearing better than $25 each :) ) and still have the remaining battery parts at home.

    JeffD
  12. seilerts

    seilerts Battery Curmudgeon

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    Pull the battery out and take the cover off. That will tell the story. On a car with your age and mileage, even though the flowchart for P3006 says to replace the ECU, I'd give it 99% that it is the pack or corrosion at the sense wires. The only way to know for sure is to pull it out and take it apart. The traction battery autopsy thread is a good source of information.

    http://priuschat.com/forums/generation-1-prius-discussion/84017-nhw11-traction-battery-autopsy.html
  13. Flying White Dutchman

    Flying White Dutchman Senior Member

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    :confused: 0,1 volt or less?
    o wait you mean 100milivolts? and ,06 is 60 milivolts?
    yes that high....
    just checking if its not 0,006volts and so 6 milivolts what is normal.:confused:
  14. seilerts

    seilerts Battery Curmudgeon

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    The ECU tries to keep a 0.1V or less balance throughout the pack. The pack is managed in groups of 14 cells/2 modules. Each cell has 1.2V nominal. Hence the average across 14 cells is 0.7V/12 ~= 0.06V. If you look at SoC curves for 1.2V NiMH cells, you'll see that 0.06V is approximately the difference between 80% and 40% -- full and empty if you are a Prius.
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  15. no trust

    no trust Junior Member

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    you always have the do it yourself rebuild option! I rebuilt my HV battery with two of Jeffs modules, over 10000 miles with no problems , cost $70. To update you Seilerts , the modules now read 7.51v and 7.36v untouched from the rebuild , the 7.36 module was the one that stood out from the rest.
    2 people like this.
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