1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Installed new 12v Accessory battery, broke negative post

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by ggarb, Jun 28, 2017.

  1. ggarb

    ggarb Member

    Joined:
    Apr 5, 2004
    86
    10
    0
    Location:
    Silicon Valley, CA
    Vehicle:
    2004 Prius
    Model:
    N/A
    I have a 2004 Gen II Prius.

    I replaced the OEM 12v accessory battery in 2012 with an Optima Yellowtop.
    Last week I noticed some weird behavior that from experience I knew meant the battery was failing.
    The battery had a three-year warranty and I got almost five years of use, so no worries there.

    When I originally bought the Optima Prius Yellowtop five years ago the only place I could get it was directly from Optima, shipped to me. Now it's stocked by several auto parts chains, and I found one locally at Pep Boys. No shipping cost since I was able to just pick it up, and promo price 25% off too!. I suspect it sat on their shelves for a while, since when I hooked it to my Optima charger it only showed 75% charge. (I did the trick of attaching the charger to the fusebox +12v and ground, to keep 12v to the car so I didn't lose any radio or system settings when I changed out the 12v accessory battery.)

    Anyway, I opened the Prius trunk area to get to the battery, and found this beautiful blue mound on the negative terminal. Copper sulphate I suspect. Vacuuming and scraping it off, I couldn't get the negative terminal completely clear and open. And its brass nut has seen better days.

    After cleaning that cable as best I could with a brass wire brush, I attached the ground cable to the battery.
    Alas, since I couldn't open the terminal fully, it sat a couple of milimeters above the battery top. But still made solid contact with the negative post. When I was tightening the brass bolt unfortunately there was a bit of extra torsion, and when the bolt stopped turning the lead negative terminal bent. I removed the cable, and bent the post back with some gentle hammer taps. When I bent it back it cracked. I gently tapped it back together, put the cable back on, tightened it tightly but gingerly, put the battery into the car, reconnected everything.

    The car works fine. I want to replace that ground cable with a new one, so it will sit flush and make more secure contact with the ground post. I checked with eight Toyota dealers here in the local Bay Area; five of them had their Parts Department open on Sunday. None had that ground cable (821.234.7020) in stock. All would be happy to order it from me from the same local Toyota Parts warehouse, at prices ranging from $38 to $45. I can get it online for $22.

    What I want is advice on whether I need to replace my brand new Optima Yellowtop Prius battery because of the cracked negative post. Or can I be confident of a reliable mechanical connection when I carefully install a fresh cable. (I will also apply some sort of corrosion protectant.)

    ==

    Is OptimaJim still in this forum?

    IMG_2962.JPG IMG_2968.JPG IMG_2983.JPG IMG_2988.JPG IMG_2995.JPG IMG_2997.JPG IMG_2999.JPG IMG_3005.JPG
     
    #1 ggarb, Jun 28, 2017
  2. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,525
    8,429
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    I believe the center is hallow. Does the battery still charge properly? It might start leaking gases
     
    #2 JC91006, Jun 28, 2017
    ggarb likes this.
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,200
    6,482
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    1. The tightening torque for the battery cable connectors is 53 in.-lb, which is less than 5 ft.-lb. My guess is that in order for you to have bent the battery post, you were exerting 20 ft.-lb or more of force.
    2. By the way, the tightening torque for the hold-down clamp is 48 in.-lb. Excessive torque there may result in a cracked battery case.
    3. My further guess is that you had damaged the previously-installed battery negative terminal, which is why acid leaked out of the battery case to form the blue corrosion coating the negative terminal.
    4. I would recommend that you not allow the newly-purchased but damaged battery to remain in service unless you are OK with battery acid continuing to leak out of the battery case.
    5. An excellent idea to replace the negative battery cable now.
    6. Examine the photos of the battery cable connector and notice the poor condition of the nut. That implies an improper tool was used to loosen/tighten the nut, and/or excessive force applied to the nut.
    7. When I remove/tighten the battery cable connectors, I use a 10 mm box wrench with two fingers holding the wrench, to reduce the likelihood of applying excessive force. You may need to use a 3/8" or 1/4" torque wrench to help you determine the force required by a 53 in.-lb torque spec.
     
    #3 Patrick Wong, Jun 28, 2017
    Last edited: Jun 28, 2017
    ggarb, Mendel Leisk and xliderider like this.
  4. xliderider

    xliderider Senior Member

    Joined:
    Apr 19, 2012
    7,921
    3,144
    0
    Location:
    Honolulu, HI
    Vehicle:
    2011 Prius
    Model:
    Three
    A paste of baking soda and water is recommended for cleaning corrosion from battery terminals. Use an old toothbrush.
     
    #4 xliderider, Jun 28, 2017
    Last edited: Jun 28, 2017
    ggarb likes this.
  5. edthefox5

    edthefox5 Senior Member

    Joined:
    Jul 25, 2007
    10,096
    4,817
    0
    Location:
    Clearwater, Florida
    Vehicle:
    2007 Prius
    Model:
    Two
    Every auto parts store and Walmart sells a battery ground jumping lead.
    It's a universal lead.
    At the very least they sell the a universal clamp you could have cut the cable off and attached it to a new universal clamp and left the rotten clamp attached to the old battery
    Apply grease to all connections and sand down the body contact area where the negative lead attaches. If you have to use a tirque wrench to install a battery and it's clamps you have no business doing that.
     
    #5 edthefox5, Jun 28, 2017
    ggarb and M in KC like this.
  6. Mendel Leisk

    Mendel Leisk EGR Fanatic

    Joined:
    Oct 17, 2010
    56,693
    39,237
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Yeah, I use a torque wrench whenever practical, but for battery cables, just a light turn of a box wrench, with your hand nearer the center of the wrench, to limit your leverage, that's the way to do it.
     
    #6 Mendel Leisk, Jun 28, 2017
    ggarb likes this.
  7. ggarb

    ggarb Member

    Joined:
    Apr 5, 2004
    86
    10
    0
    Location:
    Silicon Valley, CA
    Vehicle:
    2004 Prius
    Model:
    N/A
    Yes, but the GEN II Prius accessory battery uses Japanese market posts that are smaller than American market battery posts. So I think I prefer to get the exact size to replace with.


    iPhone ?
     
    #7 ggarb, Jun 28, 2017
  8. NavyLCDR

    NavyLCDR Active Member

    Joined:
    Oct 15, 2016
    188
    121
    4
    Location:
    Stanwood, WA
    Vehicle:
    2011 Prius
    Model:
    Three
    Then protect it with this. I have it on all my battery terminals and it is great stuff. I even had a leak in a drain in my house furnace that drips down onto the flame sensor. Fixing the leak would be expensive, but I usually had to take the sensor out and clean the contact points a two or three times every winter. Last time I cleaned it, I covered it with this protectant and haven't had to clean the sensor in over a year now.
     

    Attached Files:

    #8 NavyLCDR, Jun 28, 2017
  9. ggarb

    ggarb Member

    Joined:
    Apr 5, 2004
    86
    10
    0
    Location:
    Silicon Valley, CA
    Vehicle:
    2004 Prius
    Model:
    N/A
    Patrick,

    I examined the negative post from the just retired battery, and you are correct, there was a crack in the post that allowed sulphuric acid gas to escape and cause that copper sulphate growth.

    When I get the replacement cable I'll also get another new battery. Taking your advice, I'll be very gentle with that connection!

    Thanks!


    iPhone ?
     
    #9 ggarb, Jun 28, 2017
  10. 69shovlhed

    69shovlhed Surly tree hugger

    Joined:
    May 13, 2012
    2,170
    750
    0
    Location:
    Delaware
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    when I bought my optima, I didn't notice the tiny little garbage terminals on the oem battery, and bought the same sized battery with normal posts. since the store didn't have a correct prius battery, I replaced my negative cable with a universal cable from the parts store, and replaced the + terminal with a little fabricating, so now I have normal, better terminals that don't need to be babied like the oem crap. you might want to do the same to avoid ordering a special cable when you must use your car now.
     
    #10 69shovlhed, Jun 28, 2017
(You must log in or sign up to post here.)