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Battery condition question

Discussion in 'Gen 3 Prius Main Forum' started by GuamKelly, Jul 13, 2021.

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  1. GuamKelly

    GuamKelly Member

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    OK, I had a run of Bad Car Karma. First the battery went out on my wife's Prius V (immediately after the warranty expired and the dealer was no help, but of course). I ordered and installed a battery from Greentec Auto, all new cells, plugged right in, runs good as new.

    Then the battery went out on my son's 2008 Gen 2, with 138,000 miles. The car isn't really worth the couple thousand dollars a new battery would cost, so I pulled the old one to have a look-see. I don't have any fancy diagnostic gear, but was startled to find all the cells were at 7.5 volts or slightly better (range 7.52 to 7.57), BUT all the Bus Bars and the connector for one side of the 240 volt line were badly corroded. Could that alone cause a Red Triangle of Death?

    I have ordered new Bus Bars and nuts, and will use baking soda and vinegar to clean that connector. When I put it back in, do I need to face Mecca while saying my prayers? Moreover, is there any way to check the capacity of the cells while I have it out?
     
    #1 GuamKelly, Jul 13, 2021
    Aaron Vitolins likes this.
  2. PriusCamper

    PriusCamper Senior Member

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    Next step is to connect your headlight bulb if its a standard 12v 50w halogen to each module for two minutes and record how low the voltage drops after 2 minutes before you disconnect it. A healthy module will drop 0.3v to 0.45v. A bad module will drop much more than that. Good news is once you find the bad module they only cost $30 to replace. Let us know if you need a source to buy from?
     
    #2 PriusCamper, Jul 13, 2021
  3. Aaron Vitolins

    Aaron Vitolins Senior Member

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    Yes it can. My 2004 Prius battery was corroded so badly it caused the battery ECU inside the battery back to fry right at the connector. I’ve seen a few other people experience the same thing due to heavy corrosion. Hopefully yours isn’t that bad, new bus bars will be good start.

    I put nickel plated bus bars and nuts, they have been working flawlessly for almost 2 years.
     
    #3 Aaron Vitolins, Jul 13, 2021
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  4. GuamKelly

    GuamKelly Member

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    III

    Likely the same ones I ordered!
     
    #4 GuamKelly, Jul 13, 2021
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  5. GuamKelly

    GuamKelly Member

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    III
    And in fact, I just replaced that ECU a couple months ago on the Dealers recommendation -- at the time they said the battery was OK and I was so relieved. Have ordered the new bus bars. Hope I don't need another ECU!

     
    #5 GuamKelly, Jul 13, 2021
    Last edited: Jul 13, 2021
  6. Aaron Vitolins

    Aaron Vitolins Senior Member

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    Hopefully not! Please keep me updated. I bet it’ll be running better then ever :)
     
    #6 Aaron Vitolins, Jul 13, 2021
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