battery + terminal replaced = flat battery

Discussion in '80-Series Tech' started by semlin, Jun 20, 2005.

  1. semlin

    semlin discouraged user

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    changed the positive battery terminal on the 80 last night. Started it last night and it worked fine. This morning I have a flat battery with the alternator indicator showing 1/4" below half way. I got a quick jump (it instantly turned over) and came to work with the jumper cables. I suspect the after market alarm could be the problem, but thought I'd check if I might have done something else wrong.

    -I used a "mil spec" battery terminal from NAPA. Used a wire battery cleaner on the terminal and post and got a good connection. It was a tight fit and I had to tap it on with a mallet.

    -I drilled out the factory starter cable lug hole to fit the 3/8" bolt hole on the terminal. There was not a big amount of metal removed and it is still plenty sturdy to my eye.

    -replaced the fittings on the other three wires. There were two wires off a black box and one wire off a grey connector. One of the wires off the black box was such a light gauge that I twisted it round the wire from the grey connector and put them both into one connector. The connectors are heat shrink beldons from napa and I crimped them.

    Any suggestions on what I did wrong?

    the old terminal was so loose I could remove it by hand and it would not tighten anymore yet it always started unless I was offroad and it worked loose in which case jiggling it worked.
     
  2. Rich

    Rich

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    Clarify "had t tap it on with a mallet". The internal connection between a battery post and the battery plates can be broken by hammering on a battery lug. This is potentially the problem. My habit, if needed, is to spread open a battery lug before installation, in order to avoid needing to use any force to place it on the battery post.
     
  3. semlin

    semlin discouraged user

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    uh oh
    tapped it pretty hard but the pole did not seem to move. I tried spreading open the terminal but it did not open.

    So why would that produce a low alternator reading? I would think it would look strong until you applied some load.
     
  4. Rich

    Rich

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    Is your gauge a voltmeter or an ammeter? My 97 has only a voltmeter, and a dash light to indicate alternator problems.

    An internal battery problem can result in low voltage. With engine off fully charged battery should be a little less than 13 volts. With engine running and a properly operating alternator battery should show around 14.5 volts.

    The most interesting reading would be the voltage when trying to start. A bad connection would result in a very low voltage under high loads.
     
  5. Cruiserdrew

    Cruiserdrew On the way there SILVER Star

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    It does seem like an odd problem. You didn't damage one of the fusable links while you were adapting them to the military terminals? They are pretty easy to mess up-I ruined a set doing exactly the same thing. I don't know why that would cause a discharged battery though. Unless you really wailed on the post, I doubt you damaged it very much. Look for unswitched loads that could drain the battery.
     
  6. semlin

    semlin discouraged user

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    i am pretty sure the dash gauge is a voltage meter. turning the ignition when it was dead caused the voltage to drop another 1/8" on the dial but a dead battery will do that.

    Andrew, I don't see how frying a fusible link would drain the battery either but I did leave the negative terminal on the battery like an idiot and only thought about it when I was done :rolleyes:
     
  7. Scamper

    Scamper

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    Dash gauge is a voltmeter.

    I agree with Rich that you may have mangled your battery with the mallet. You may still read 13-14 volts (it would only require a tiny amount of current to give you a voltage reading), but you may not get the current draw you need to start the engine if you've done it damage.

    But before I draw this conclusion, was the battery fully charged when you put the new cable end on? Could it have been discharged already, and you just conincidently replaced the end as it died?
     
  8. semlin

    semlin discouraged user

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    I doubt the battery chose that exact moment to die. It started strong after I installed the new terminal last night.

    The tapping on the post sounds like a good reason except that I still don't understand why I showed such a low voltage this morning if that's the cause. When I parked it after driving to work (3 miles) the voltmeter was back up to the half way point (and it turned over). It seems more like a discharge problem.
     
  9. Rich

    Rich

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    A good start after installing the new battery lug appears to indicate that the battery was ok at that point in time.
     
  10. Rich

    Rich

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    Another possiblity, though perhaps remote, is that the hammering resulted in lead sulfate falling off the plates, piling up at the bottom, and shorting out some plates. This is one, not so uncommon, failure mode of old batteries, which can happen without any physical abuse of the battery posts.
     
  11. semlin

    semlin discouraged user

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    well I own a new battery.

    I left the truck sitting for 36 hours and the battery got no flatter and would still operate any accessory but would not turn over the motor at all. There did not appear to be any discharge. Took it to the battery place and they tested it. Said the pole connection was fine but that one of the cells was bad. They popped the cell lids, chcked the fluid then applied a load to the battery with a tester and one of the cells started smoking and bubbling. He said it was a complete coincidence it lost the ability to turn over the motor the morning after I replaced the terminal.

    Not sure if I believe this but time will tell I guess.

    I bought the battery from a commercial battery supplier that manufactures their own batteries. Group 27 sized battery (tight fit) with 880 CCA and 170 minutes reserve time with a 5 year warranty for $C110, or about $90us. The only other battery brand they sell are optima yellowtops but he said that although they are theoretically tougher and good for exposed locations, they get a lot of returns for unexplained failures. He also pointed out that having extracted 7 years of life from my undersized diehard (the truck came with it 3 years ago), I probably didn't do anything in the truck to merit a yellowtop. Damn, the battery guy just called me out as a mall cruiser owner :rolleyes:
     
  12. e9999

    e9999 You want to do what...? Moderator

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    yes, but also rhodo mover! did he know about that? :D
     
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