Charging a Dead Prius C Battery

Discussion in 'Prius c Technical Discussion' started by Daddio, Jun 8, 2012.

  1. Daddio

    Daddio New Member

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    This is best done by someone with a fair amount of automotive and/or electrical experience and is only appropriate when you have an electrical outlet nearby. To avoid removing the rear seat to access the 12 volt starting battery directly, open the hood; then pop the lid on the triangular shaped fuse box at the driver's side near the windshield. You'll see a thick white cable. You don't need to disconnect it. Stick the positive probe of a test meter in the connector so it touches the metal terminal of the cable connector. The probe should stay in place. This is a direct 12 volt positive connection to your battery. Then, touch the negative probe to any part of the "Hybrid Synergy Drive" unit next to the fuse box or any non-painted metal part. Confirm you have about 12 volts reading on the meter. Then, disconnect the positive probe from the meter leaving the other end in the thick white cable and connect the positive lead of a 12 volt battery charger to the probe. You don't need the negative probe. Clamp the negative terminal of your 12 volt battery charger to the "Hybrid Synergy Drive" or other bare metal surface under the hood. You are not hooking up to the "Hybrid Synergy Drive," just using its large metal surface as a negative ground point. When your charger in turned on, it should indicate a normal rate of charge of, say, 5 amps or so diminishing as the battery charges up. This is not appropriate for jump starts as the current drain is too high for the thin gauge meter probe unless you find a way to connect a jumper cable directly to the heavy white positive cable but it will get your dead battery charged and your Prius c going in a few hours.
     
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  2. Oldwolf

    Oldwolf Prius Enthusiast

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    Thanks. A picture would be great for future reference.
     
  3. XRinger

    XRinger Member

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    [​IMG]

    The white cable is easy to find, but connecting a charger clip to it might be problematic.
    There isn't much exposes copper. Putting a VOM probe down there would be easy,
    but I'm not sure if you would want to charge a dead battery with a test probe lead.
    If it's really flat, your charger might want to deliver high current, when first connected.
    IIRC, my Sears charger does have a 5A mode, so meter probe would work fine.

    I noticed that large (blue) fuse to the right of the white cable connector is rated for 100 Amps.
    I wonder if that's the 12v battery fuse?
     
  4. bisco

    bisco cookie crumbler

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    100 amps should be the hybrid battery. strange, the hatchback has a charging post.
     
  5. XRinger

    XRinger Member

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    100a x 144v = 14.4 kw and that's only about 19.3 hp.. Which seems a little low.
    But, 100a x 14v is only 1.4 kw, a little less than 1 hp. Seems like that might be more like an engine starter load..

    This is from a battery maintenance pdf. "Electric Motors 60 hp (45 kW), Permanent Magnet Motor "
     
  6. fuzzy1

    fuzzy1 Senior Member

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    Not in that location, with that little clearance and creepage distance to low voltage stuff, and without the bright orange high voltage warning colors.
     
  7. Daddio

    Daddio New Member

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    --- Good photo. I should have specified, use a low rate charger or one with a low (1 to 5 amp) setting. Mine is 5 amps and it seems to work fine. Also, and this should be obvious, be careful to keep to leads from touching.---
     
  8. Daddio

    Daddio New Member

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    --- I should have specified, use a low rate (1 to 5amp) charger. Mine is 5 amps and it seems to work fine. Also, and this should be obvious, be careful to keep to leads from touching. ---
     
  9. XRinger

    XRinger Member

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    You can say that again! I have a solar+battery back-up system. Plus over the years, I've seen the damage that current from a small car battery can do.

    Looking at that picture, it sure looks like a great place to attach a clamp-on DC Amp meter probe,
    just in case you ever needed to see how much current the 12V components were using.
     
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