Announcement

Collapse
No announcement yet.

car battery

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • car battery

    after having been sitting for two weeks or so the car wouldnt start. the battery measured at 8v, i thought i had left a dor open. the electonic charger wouldnt charge so i put it on a "simple" charger. after a short while the voltage was 14.5v but when disconnected it was still around 8v. after severar hours the charging voltage droped to 9v. i left it on the charger for a couple of days. the 70 ah battery was taking 1.5 amps. now the charging voltage is 8.15v. when i connect a 55w light bulb voltage rises to 8.5v and declines slowly to 8.3v. then its again 8.15v on the charger.

    what has happened to the battery? what failure mode is that? is there hope of restoring to some extend and how?

    actually it happend several times: fast rise on charger (at 1.5 amps) to 14.5v, then drop to below 10v. i guess its a cadmium battery but i dont really know. its sealed without "magic eye". 750a/70ah din.

  • #2
    A consistent 8 volts means that you have shorted out two cells. When you use the charger to bring them to 14.5v you are over charging the 4 cells that are still working.

    I don't know if that's from lead flaking off the plates and accumulating at the bottom of the battery, or if it's from plates warping. My big brother once told me that he got another few months out of a battery with a shorted cell by shaking it. I would think that would be a dangerous thing to do to a box full of acid.

    It's time to get a new one.

    Dan
    At the end of the project, there is a profound difference between spare parts and left over parts.

    Location: SF East Bay.

    Comment


    • #3
      btw, im not considering putting it back in the car, but it might be good for other uses. i once had a "dead" battery for about 10 years that was very handy. buti would have to bring it back up to 12v.

      Comment


      • #4
        The four "good" cells are just as old as the two failed ones; they just haven't shorted out yet. The battery is ready for recycling.

        Comment


        • #5
          Originally posted by AntonLargiader View Post
          The four "good" cells are just as old as the two failed ones; they just haven't shorted out yet. The battery is ready for recycling.
          I like that logic.
          A few times I have replaced a headlamp bulb,
          only to have the other side blow the next week.

          -Doozer
          DZER

          Comment


          • #6
            I found that I could buy a premium quality cheaper on line from a bettery warehouse than the garage, or motor factors prices, its worth checking.

            Comment


            • #7
              Originally posted by danlb View Post
              My big brother once told me that he got another few months out of a battery with a shorted cell by shaking it.

              Dan
              My brother went even further. He would drain and retain the acid, then thoroughly rinse the battery to get all the residue out of the bottom of the battery. Refill and recharge and good to go for another year. I never tried it.

              Mike

              Comment


              • #8
                The shorted cells can be due to lead sulfate flaking off the plates and falling to the bottom of the battery, eventually piling up enough to connect two plates, or from lead sulfate building up on the plates with enough growth until two adjacent plates are bridged. Sometimes dropping the battery on concrete a few times (not from very high, maybe 6-12 inches) will bring them back for a little while, but usually not for long. The best way to prevent this as long as possible is to keep the battery on a float charger or battery tender. I have had batteries last 10 years when using one. The sulfation accelerates when battery voltage is depleted.

                Comment


                • #9
                  Originally posted by MikeL46 View Post

                  My brother went even further. He would drain and retain the acid, then thoroughly rinse the battery to get all the residue out of the bottom of the battery. Refill and recharge and good to go for another year. I never tried it.

                  Mike
                  Iv done that with mixed results (cuz im so cheap lol)

                  Im thinking it's sediment catching up to the plates --- try to find a date on the battery and it will make you feel better about replacing it if it's past due,,,

                  I just replaced one for a gal with the same symptoms - she got about 7 years out of her old one, the nice surprise was it was a real popular one and Wal-Mart stocked it for only 59 bucks! I have not seen that kinda pricing in years, yeah it was their bottom line but still - the local auto parts stores were selling "reman's" for 10 bucks over that cost and all they are is flushed and refilled old eaten away crap...

                  Comment


                  • #10
                    Originally posted by Doozer View Post

                    I like that logic.
                    A few times I have replaced a headlamp bulb,
                    only to have the other side blow the next week.

                    -Doozer
                    when one bulb goes I always replace both and stick the unblown old one in the trunk as an emergency replacement. Only needed it once, but it was at the start of a 4h drive home in the dark, so handy to have.

                    Comment


                    • #11
                      A weak battery is one thing. Those we can use for a while in the shop or for some other 12v application. But this one has bit the dust rather firmly. Just turn it in for recycling.
                      Chilliwack BC, Canada

                      Comment


                      • #12
                        Originally posted by BCRider View Post
                        A weak battery is one thing. Those we can use for a while in the shop or for some other 12v application. But this one has bit the dust rather firmly. Just turn it in for recycling.
                        I imagine that it could have uses... Assuming that two of the cells are firmly shorted, you are left with 4 cells that are usable for low power purposes. Imagine a solar charger that feeds the battery which as a buck (step down) converter to run a house full of LED emergency lights. Imagine using it for your ultimate USB cell phone charger during power outages.

                        Table 4 of this page ( https://deepcyclebatterystore.com/ho...ain-batteries/ ) has the proper voltages for maintaining an 8 volt battery. One thing you should never do is to charge a damaged battery on a full 14.5v charger.

                        Dan
                        At the end of the project, there is a profound difference between spare parts and left over parts.

                        Location: SF East Bay.

                        Comment


                        • #13
                          I agree with BC Rider, that battery is probably beyond hope. I have a pulse recovery unit that I have used on batteries where the capacity is starting to drop off. I usually put it on a battery along with a slow charger. It knocks the sulfate off the plates and will sometimes bring a battery back to life for a while longer.
                          Another bit of information if anyone is using gel cell batteries. When they get lazy and loose some capacity you can bring them back by putting them upside down and connect a decent load until it is completely dead. Then leaving it upside down charge it up at a pretty high rate. Do this cycle a few times and the battery usually will come back. I don't remember where I got this information, but I tried it and the battery was good again for a year or two. I believe they are like a nicad and will develop a memory if lightly loaded and slow charged over and over for a period of time. They just need a kick to wake them up again. Why upside down I have no idea. Maybe the gel will move around inside the battery somewhat and help to revive it.
                          Larry - west coast of Canada

                          Comment


                          • #14
                            You might be able to drill small holes in the top of the battery case to access the series connections, and thus identify which cells are shorted. Maybe even make a hole large enough to drill and tap into the conductor and apply a solid shorting jumper, to see if the remaining cells are strong enough to be useful. I would not depend on the internal short to be reliable. I have tried draining the electrolyte from a weak battery, flushing the cells with a blast from a hose, and then filtering and replacing the acid. But it was not very successful.

                            It might be better to buy a used battery from a junk yard. I think the going price is around $30-$40, and you might get a nearly new battery.
                            http://pauleschoen.com/pix/PM08_P76_P54.png
                            Paul , P S Technology, Inc. and MrTibbs
                            USA Maryland 21030

                            Comment


                            • #15
                              Originally posted by MikeL46 View Post

                              My brother went even further. He would drain and retain the acid, then thoroughly rinse the battery to get all the residue out of the bottom of the battery. Refill and recharge and good to go for another year. I never tried it.

                              Mike
                              A guy that owned a auto salvage yard told me the same thing , but I have never tried it !

                              Comment

                              Working...
                              X