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  • Recovering a starter battery?

    I know it's a lost cause but I just might learn something so I'm messing around with this.

    I have an old 6 volt lead-acid starter battery that still has fluid in it but was low so I topped it off with distilled water. It didn't require a lot of water surprisingly.

    I'm using an old transformer style battery charger. They are notorious for over charging and ruining batteries so I have a variable voltage regulator (variac?) plugged into the wall. The charger is plugged into the variac. I have the charger clips on the battery and the clips are also holding the probes of a volt meter against the battery posts.

    I have the variac adjusted so I'm getting about 7 volts out of the charger on the 6 volt setting. I'm not sure if that is enough voltage to begin desulfation but thought it was a good place to start.

    I've had this set up and running for a couple of hours and all seems okay. No adverse reactions so far.

    I thought I'd let this sit in an out of the way spot and percolate for a month or so to see if it did anything. I will monitor it and adjust the variac as needed.

    Like I said, I just might learn something.

    I think the battery is probably a goner but stranger things have happened.

    Am I on the right track?
    Last edited by ; 07-21-2017, 10:58 PM.

  • #2
    You might try draining the fluid out of the battery (save it). Then use plenty of water to rinse debris from the bottom of the cells. As this debris builds up it shorts out the cells. After it is really clean put the acid water back in and charge it. Usually this works at least once.

    Mike

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    • #3
      Are you trying to knock sulfides off the plates with 7 volts?
      Why would you do it for more that a day or so ?
      Many old batteries have been brought back by a trickle charger or very weak charger.
      Last edited by 754; 07-22-2017, 03:11 PM.

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      • #4
        754,

        While a car is running its 12 volt battery is being charged at ~13.8 volts. Half of that is 6.9 volts. That was my reasoning for starting with 7 volts but I'm open minded on that. When a 6 volt battery is fully charged it will be at around 6.3 to 6.4 volts.

        At what voltage does a trickle charger for a 6 volt battery charge? It has to be more than 6 volts. Do they run at 7 volts or 6.5 volts or 7.5 volts or ???

        That's the type of information I'm asking about with this thread.
        Last edited by ; 07-22-2017, 08:25 AM.

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        • #5
          Just checked. After almost 14 hours the battery is drawing ~0.5 amp at 7 volts.

          Last night I saw no noticeable current draw but the old charger has a coarse ammeter that is marked in 1 amp increments.

          No noticeable bubbling in the cells.

          Sound normal or not?

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          • #6
            Sounds just as I would expect from what I have experienced. I have an old sulfated 12V battery on solar charge now, it's been on solar trickle charge with a half amp "maintainer" for a couple weeks. It's measuring up to voltage, but has no real discharge capacity yet. The maintainer started at 20 V, and has come down to measure 12V across the battery.

            I may make a pulse circuit to see what that does.

            Originally posted by 754 View Post
            Are you trying to knock suicides off the plates with 7 volts?
            Why would you do it for more that a day or so ?
            Many old batteries have been brought back by a trickle charger or very weak charger.
            As I see it, his plan is to recover the now 100% "sulfated" battery.

            The high voltage is to extend the charge out to the "inaccessible" sulfate. After sitting a while, the normally occurring sulfate (part of how it works) becomes re-crystallized in such a manner that it is not participating in the charge reaction. A high voltage can sometimes "extend the charging effect" out into the electrolyte and convert that inaccessible sulfate which is not directly "electrically" connected to a plate.

            But, just charging does not do that, because as soon as any sulfate is converted, the battery tends to hold the voltage down. So "pulse" chargers were invented. The "pulse" chargers apparently give high voltage (20 or 25 volts) pulses at higher current capability, so as to keep the voltage up. When only a little sulfate is converted, the battery still has a high impedance, so it does not take that much current to raise the voltage.

            It's a good theory, and folks claim good results. Of course many claimed good results from "Carter's little liver pills" too. I do not know if it really works as well as claimed. In theory it CAN work, the quesion is how well it really recovers a battery, in terms of the actual battery capacity of the recovered battery vs what it was when it was new.

            Any sulfate that has fallen off the plates is lost, nothing can really recover that lost capacity.
            Last edited by J Tiers; 07-22-2017, 09:53 AM.
            CNC machines only go through the motions

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            • #7
              does baking soda attack sulfate? might be another Dr. Kilmers swamp root kidney cure but I think if you found what ate away at sulfate you would then re-expose the lead plates and get back in business esp. with the older style batteries that just had standard thick plates with no fancy waves and pockets to expose more surface area...

              if the battery was drained and the electrolyte saved and then you flushed it over and over to remove all baking soda residue then it might bring things back around...

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              • #8
                I have a pulse recovery charger that does work sometimes. Depending on how far gone the battery is it will help knock the sulfate off the plates and give you another year or two out of the battery. I like the little pulse units that you connect to a battery bank, preferably when the batteries are new, to help keep them from sulfating. I have seen a house bank in a yacht last 10 to 12 years with one of these units in operation.
                Larry - west coast of Canada

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                • #9
                  The sulfate is ESSENTIAL to the battery. You do NOT want to get rid of it.

                  What you want is to get it back to condition where the battery can charge. The sulfuric becomes sulfate when the battery is discharged. When charging, the sulfate is driven back into the water as sulfuric acid.

                  A "sulfated" battery has sulfate which has sat, and has taken a form which does not easily get electrochemically driven back to become sulfuric acid.

                  If you get rid of it, you no longer have a battery.
                  CNC machines only go through the motions

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                  • #10
                    This seems to work https://www.youtube.com/watch?v=Supe1a3LW2U

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                    • #11
                      As far as youtube goes, this guy is the best on this subject I've encountered so far. His whole series of videos is very good, IMHO.

                      https://www.youtube.com/watch?v=6x-JfckAt20

                      The reason I asked questions here is that my battery differs from this guy's batter by quite a bit. Plus it never hurts to come here and ask the experts.

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                      • #12
                        Originally posted by J Tiers View Post
                        The sulfate is ESSENTIAL to the battery. You do NOT want to get rid of it.

                        What you want is to get it back to condition where the battery can charge. The sulfuric becomes sulfate when the battery is discharged. When charging, the sulfate is driven back into the water as sulfuric acid.

                        A "sulfated" battery has sulfate which has sat, and has taken a form which does not easily get electrochemically driven back to become sulfuric acid.

                        If you get rid of it, you no longer have a battery.
                        would not be the end of the world, you can still buy battery electrolyte in plastic lined cardboard boxes and then just add it yourself

                        so if you could get rid of it all and start with just "lead" then add electrolyte then all is back to balanced --- no different then what I did at the motorcycle shop, batterys came in without electrolyte - they stored forever with no problems - just add the "juice" when you sell one or need one on the spot...

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                        • #13
                          Originally posted by A.K. Boomer View Post
                          would not be the end of the world, you can still buy battery electrolyte in plastic lined cardboard boxes and then just add it yourself

                          so if you could get rid of it all and start with just "lead" then add electrolyte then all is back to balanced --- no different then what I did at the motorcycle shop, batterys came in without electrolyte - they stored forever with no problems - just add the "juice" when you sell one or need one on the spot...
                          Just one small but basic problem.

                          Batteries are made with "pasted" plates. The pasted plate is a grid, loaded with PbO2 paste when in the charged condition, which is what is converted to lead sulfate as it is discharged.

                          If you knock off/dissolve away/etc the "paste", all you have left is the lead alloy grid, which is not supposed to be part of the charging reaction.

                          As said before, it would no longer be a battery as far as actual use is concerned. The day of actual lead plates has been past for about a hundred years.
                          CNC machines only go through the motions

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                          • #14
                            Originally posted by J Tiers View Post
                            The day of actual lead plates has been past for about a hundred years.

                            You got me there,,, I thought his battery would have been as basic as they get...

                            so once the sulfates get knocked off they dissolve instead of clogging up the bottom plates and shorting them out?

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                            • #15
                              https://www.electrical4u.com/constru...-acid-battery/

                              I have a 4 wheeler battery I'm going to try the baking soda rinse, swirl, dump repeat just to see. I think the key is getting the sulfation out of the battery & all the other methods just break it loose where it drops to the bottom & shorts the plates. Forklift batteries are rebuilt all the time but I couldn't find direction on how they do it. I have a 4000# 36volt in the 6500# cap Yale but it's in good shape.

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