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Newpriusbatteries install problem with positive and negative

Discussion in 'Gen 3 Prius Technical Discussion' started by DirkG, Nov 8, 2020.

  1. DirkG

    DirkG Junior Member

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    I just got this in for my 2010 and I have read the directions dozens of times and the extra email instructions and everything seems backwards.
    According to the instructions and email pack 1 goes next to the ecu but it also says this short wire should be my main positive wire and the long one my main negative. Well the top of pack 1 is negative as seen in the picture. The oem battery that was in that slot was negative also. Am I right in just hooking this short wire back up to the negative post on pack 1 even though directions say this is the positive wire?
     

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  2. ASRDogman

    ASRDogman Senior Member

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    Contact NewPriusBatteries. Get it straight from the seller! Can't go wrong.
     
  3. DirkG

    DirkG Junior Member

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    I need this done tonight. I need the car for work at 6am Monday.
     
  4. DirkG

    DirkG Junior Member

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    Ok, nevermind. His instructions are backwards. The shortest mainwire is the negative wire. I traced it back the ecu and the shows that side as negative.
     
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  5. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    There are 2 different harnesses and likely different instructions for Gen 2 vs Gen 3. I hope you received the proper ones.

    @2k1Toaster is here quite often.
     
  6. edthefox5

    edthefox5 Senior Member

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    There are 4 big cables that have that kind of lug on them.

    2 are the safety switch legs
    2 are the + and - neg side of the battery side relay.
    The short one is the negative that goes to the negative side of the relay.
    The positive is the long one and that goes to the + side of the relay.

    But I understand what your saying I found it was backwards also.

    After bolting it up and before installing the car side legs put the safety switch back in and measure across the battery side relay and make sure you have 230-240 volts and the polarity is correct. My NPB was kinda low at there at 218 volts. Its started right up though.

    Then after measuring there make sure you remove that safety switch before proceeding.

    Good Luck.
     
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  7. TMR-JWAP

    TMR-JWAP Senior Member

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    A brand new factory replacement battery from Toyota is around 218-221 volts. That's ~7.8 - 7.9 volts per module.

    Do the NPB batteries come charged up to 8.2 - 8.6 volts per module (equivalent)?
     
  8. edthefox5

    edthefox5 Senior Member

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    I thought it was going to be fully charged to max. But your right it started right up.
     
  9. ASRDogman

    ASRDogman Senior Member

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    Did you get everything straightened out and installed, and the car is running?
     
  10. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    The instructions are for Gen-2 Prius. The overall instructions which are bolded in the email sent out to all customers is "like for like". That's the only thing you have to worry about. I've seen some wonky batteries with all types of modifications. I would NEVER assume the position of the main negative and positive connections. Ever.

    As our instructions state, when you get to your old battery all you have to do is note where the main positive and main negative cables go. The original modules have (+) and (-) markings on them. Assume since the vehicle was working with those connections, that's how it should continue to be connected.

    There are only 4 possible orientations of the battery. Only 2 orientations will have the safety disconnect side match the "lower" terminals and the main connections match the "higher" terminals. Now you're down to 2 orientations total. One starts with module 1 nearest the ECU, one starts with the highest numbered module near the ECU. Only 1 of these 2 orientations will match the main positive location and main negative location. And voila, you're done.

    Like for like.

    2 harnesses, same instructions as the battery building is the same. For the Gen-3 we instruct people to see how their car is taken apart on YouTube. I don't own a Gen-3 so I can't make a detailed manual. All the Gen-3 testing was done on other's vehicles and the install took no time, but no documentation was done as there are a million videos on YT already.

    We ship them very similar to Toyota. We don't generally ship them higher than 60% SOC.
     
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