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Used jumper cables today FYI

Discussion in 'Gen 3 Prius Main Forum' started by ALS, Jan 17, 2010.

  1. ALS

    ALS Active Member

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    My other car was in the garage and had been unused since September. So I needed to give her a run for two hours to get everything up to temperature and fully charge the battery.

    Well I went to start it this morning and the battery was pretty drained. Out came the jumper cables.

    I strongly suggest that when you get a chance you familiarize yourself with the POSITIVE JUMP TERMINAL in the fuse box.

    I first read the instructions in the owners manual and when I pulled the cover on the fuse box I kept looking around for the cable connection. It took me a minute or two to find it. Mainly because it looks bigger in the manual and it looks like a blade type fuse.

    You will notice toward the back of the box a RED cover with a + that looks like a fuse at first glance. You flip up the cover exposing the metal strip. This strip is about 1 to 1.5 inches long maybe 3/4 inches wide. That's all the bigger it is. :eek:

    It was daylight when I was looking for it. I can't imagine what it would be like to find this little terminal at night when you had no idea what you were looking for.
     
    #1 ALS, Jan 17, 2010
    1 person likes this.
  2. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    One HUGE warning - the Prius is NOT meant to jump another car. Depending on the method, you're at HIGH risk for blowing the 100A main fuse (designed to protect the inverter and wiring), rendering your Prius dead in the water. This is because the 12V system in the Prius was not meant to run a high current starter, but rather to energize a few relays. Once energized, the DC-DC converter handles the accessory loads, which shouldn't come close to that 100A cap.

    Acceptable but still risky Prius jump method:

    1. Connect Prius to dead car.
    2. Start Prius.
    3. Do NOT attempt to start the dead car. Make sure all loads are off.
    4. Allow dead car to charge 10-15 minutes (+/-)
    5. Disconnect Prius from jumper cables
    6. Attempt to start dead car.
    WARNING - shorting of the jumper cables may still cause the 100A fuse to blow. Additionally, if the dead vehicle should have a short in it's electrical system, the 100A fuse could also be blown.

    Page 547 of the Owner's Manual (Toyota's official stance):

    • To prevent damaging the vehicle:
      The exclusive jump starting terminal is to be used when charging the 12 volt battery from another vehicle in an emergency. It cannot be used to jump start another vehicle.
     
    #2 HTMLSpinnr, Jan 17, 2010
    8 people like this.
  3. Boo

    Boo Boola Boola Member

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    +1 to ALS' post for jumping the Prius (and to HTMLSpnner's post re do NOT use the Prius to jump another car).

    And all the more so if you have a Gen II Prius, for which the jump starting instructions in the Owner's Manual were completely inadequate because:

    (1) The instructions didn't show or explain how to remove the fuse box cover (reach down and feel around for a square release tab at the front of the fuse box cover; push hard on this front release tab and lift the cover off the two retention guide tabs/slots at the rear of the fuse box cover). Here are two pics of my Gen II showing the front square release tab, the two rear guide slots, and the bright red door covering the positive connection point:

    [IMGLINK]http://priuschat.com/forums/members/boo-albums-prius-picture1250-open-fuse-box-cover-press-hard-square-release-tab-front-cover-lift-up-off-two-slots-tabs-hinge-rear-cover.jpg[/IMGLINK]

    [IMGLINK]http://priuschat.com/forums/members/boo-albums-prius-picture1246-two-slots-back-fuse-box-cover-hook-onto-two-tabs-hinge-back-fuse-box.jpg[/IMGLINK]

    (2) The instructions didn't show or explain exactly what was the positive connection point underneath that bright red cover (it's the tiny, square-ish, flat, vertical piece of metal ALS mentioned).

    * * * * * * *

    Another thing people should be aware of is that because of a lack of space, it is difficult to put a big jumper cable clamp onto that tiny, square positive connection point.

    Patrick Wong had a great suggestion for this -- clamp the big jumper cable clamp onto an electrical, miniature, alligator clip like this:

    [IMGLINK]http://www.muellerelectric.com/images/BU30.jpg[/IMGLINK]

    Then clamp the miniature alligator clip onto that positive connection point.

    EDIT: Sorry, I think I got it backwards. It would be better to first clamp the miniature alligator clip onto the positive connection point, and then clamp the big jumper cable clamp onto the alligator clip.
     
    #3 Boo, Jan 17, 2010
    4 people like this.
  4. ALS

    ALS Active Member

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    Thanks for the info. it looks like I'll be picking up a jump pack this week in case this happens again. Lucky for me there were zero problems jumping my other car. I got lucky this time, it's just not worth the risk frying anything in the Prius electronics.
     
    #4 ALS, Jan 17, 2010
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    If it is necessary in an emergency situation to use Prius to jump another car, you would be better off connecting the jumper cables directly to the 12V battery in the hatch floor. This eliminates the possibility of blowing the MAIN fuse. Then allow some time to elapse (20 minutes at least) so that the recipient vehicle battery can gain some charge.

    Disconnect the jumper cables before trying to start the recipient vehicle, so that the heavy load required by the recipient vehicle starter motor (may be 250A or so) will not damage the Prius electrical system.
     
    #5 Patrick Wong, Jan 18, 2010
    2 people like this.
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