WeberAuto: 2024 Prius Prime PHEV Low-Voltage Charging System Testing

Discussion in 'Gen 5 Prius Technical Discussion' started by KMO, Jan 7, 2025 at 2:52 PM.

  1. KMO

    KMO Senior Member

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    A first video from Professor Kelly on the G5 Prius, covering an new angle - what's going on with the 12V battery charging? Also covers G4 as a comparison.

    Not watched through it yet myself, but sure it'll be interesting.



    Hopefully we'll see a drivetrain disassembly soon like he's already done for the older generations soon.
     
    #1 KMO, Jan 7, 2025 at 2:52 PM
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  2. bisco

    bisco cookie crumbler

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    maybe he will get to the bottom of it, but there seems to be more than one cause from what i've read?
     
    #2 bisco, Jan 7, 2025 at 2:53 PM
  3. KMO

    KMO Senior Member

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    He promises more videos coming including HV battery disassembly - he had some stills from a transaxle disassembly too.

    One new piece of information in there is that it can charge the 12V battery while charging the HV battery - I believe we all previously thought that the DC/DC converter used by the charger only output enough to prevent discharge.

    It may be true that the charger's DC/DC converter can't charge the 12V battery - but he had a low 12V battery, and the car actually activated the main DC/DC converter with the usual 14.1V.

    A bit weird - I'd been under the impression that they wanted to keep the charging and drive systems fully separate, and there were interlocks at the battery to ensure the charger and hybrid systems were not connected simultaneously. That's clearly been relaxed. Maybe part of adding "My Room" mode which presumably needs to activate a bunch of the AC stuff, which is high-voltage? Plus the battery cooling?

    Raises the question of why have a DC/DC converter in the charge unit at all? Couldn't you always use the main one? It did seem to be the case that the G5 diagrams did show the relevant wiring and fuses for the charger DC/DC, so I'm pretty certain it still exists.
     
    #3 KMO, Jan 8, 2025 at 8:20 AM
  4. Trollbait

    Trollbait It's a D&D thing

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    The disconnect between battery and the rest of the car when shut down was a safety precaution for hybrids. Plus, it could have helped with the NiMH standby discharging. Good to continue the precaution with plug ins, though i don't know of any hard rules that says charging is the same as shut down for this.

    Toyota could have always used the main DC-DC converter during charging; I believe others do. I'm guessing they didn't want to muck too much in the hybrid software. The behavior seen here could the result of updating the software after field data showed their initial approach wasn't keeping 12Vs charged.
     
    #4 Trollbait, Jan 8, 2025 at 10:32 AM
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