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Electrolysis Power Supply; Will This Work?

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  • Electrolysis Power Supply; Will This Work?

    If I'm to sell the old boat anchors that my wife and I have picked up from the local lake bottoms, I'll have to de-rust them and make them look nice. I'm allergic to work (and to Ash sawdust, but that's another story) so I'm ready to try the electrolysis thing. After the anchors are done, it'll be time to clean up some machine parts, c-clamps, vises and the like.

    I don't have a battery charger, but I do have this variable transformer and rectifier that was once used to control a DC motor for a slow speed drive on my lathe. The transformer outputs from 0 volts to line voltage, AC. The rectifier also gives me 0 to line voltage DC. I don't have any part numbers or other info on either the transformer or the rectifier.

    So, my question is will this set-up run an electrolysis tank? How much voltage should I use? How much amperage. I assume I can control the amperage by immersing or withdrawing the waste electrode. Right?

    Should I put a circuit breaker in the DC circuit? How big?

    I'll put the transformer into a plastic box or container so I won't have exposed wiring.
    Last edited by john hobdeclipe; 09-08-2006, 09:21 PM.

  • #2

    That should just about tell it all except that I used 4 gallons of rain water, 1 cup of wash soda and 1/4 cup of phosphoric acid.

    Make sure your equipment can handle the amperage--About 10A at 12vdc. The process will take 10-12 hours.


    • #3
      Hi John,

      It will work.
      First, I would use a 1 amp fuse on the hot leg of the 120 line to the transformer.
      For the DC section, it all depends on the rating of the rectifier. It's probably safe to assume 5~7 amps, tho it may well provide more.
      Try 10 volts DC to start and see how it runs.
      I'd use a circuit breaker rated at no more than 7 amps in the DC section just to stay on the safe side. If the rectifier gets very warm while in use, heat sink it.
      To reduce current while in use, increase the distance betweem the submerged electrodes.


      • #4
        Forgot to mention: No one noticed the last time I posted these pictures but in the second picture, the Pos/Neg are reversed in error. Follow the first picture.

        Oh, and one more thing. Use rain water or distilled water only! If you use tap water that has been treated with chlorine, you'll defeat the purpose.
        Last edited by CCWKen; 09-08-2006, 09:45 PM.


        • #5
          John...I use a plain 10 amp battery charger with no provisions for power adjustments.
          I found that a 6 amp draw worked very well for even heavily rusted parts...all came shiny clean in 24 hours.
          You can adjust the amp draw by adding more soda (increases power draw) or dilute the brew with plain water (decreases power draw).
          As far as that gadjet you have there...I have no idear!
          I have tools I don't even know I own...


          • #6
            That 'gadget' is a variac, and it's an autotransformer. What that means is that the output has a connection in common with the input and the output connection is also, except for the variable voltage output. It won't be safe to use it directly like that, and the current output won't be enough to do your job. I would still use that variac, but I would run a transformer from it, and use the output from the transformer to go to the rectifier then the tank. If you can find something with a 10 to 20 amp output winding, at say 20 to 30 volts, that will do fine.

            Over all though, it might be better to use a battery charger with meters, since you then get a means of seeing what is happening with the current flow. You could run the battery charger from the variac, and that will give you some control over the current delivered to the tank.

            In any event, you will want one of the older style chargers which doesn't rely on seeing a voltage from a battery before it 'turns on' . Many are like this now, and they won't output any juice unless a good battery is connected to the terminals. That type isn't really suitable for this application.
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


            • #7
              Bolt the rectifier to an aluminum plate, preferably with some heatsink grease. That's why it has a hole in it.

              As Darryl says, it won't put out enough current from the variac and it isn't safe anyway. You need a step down transformer.
              Free software for calculating bolt circles and similar: Click Here


              • #8
                I have cooked both my 6 amp battery chargers. Abuse and ignorance will do the trick every time. Having said that, smaller battery chargers are OK if used within their limits.
                John knocked up a big arse unit for me all bolted to a sheet of MDF that delivers up to 18? amps in 6 steps. So far, so good.
                Last edited by speedy; 09-08-2006, 10:21 PM.


                • #9

                  OneUVa the guys on Adrians site, he bought a 20amp transformer, bridge and meter for less than $40 I think. All that is lacking is the appropriate resistor to limit the current less than the transformer max.. If you want 40 amps? parallel two.. sixty? parallel three.. if you add 18 volts parallel to 18, you got 18.. if you series the two, you got 36.. okay?

                  I have part numbers..

                  I used my dc welder since I was doing large areas in a livestock watering tank. 40 amps was about right for a door off the 41 truck.

                  Deadly voltages come off a welder. Just change out a rod with a wet glove and you will see what I mean.. Be warned and be safe.

                  Variacs used to be used a lot in chroming shops. I saved one for years and years only to find out the brushes had been robbed and a hand winding put in.
                  Excuse me, I farted.


                  • #10
                    I got great results (on fairly small parts - about 30 sq inch of surface) using my good old 6 amp battery charger. The problem I faced initially was not putting enough current into the tank, but I fixed that by using an additional piece of rebar on the electrode.

                    I agree with what others have said, too - I wouldn't want to run the thing directly off the AC line - find a big honkin' transformer. Current is what does the job, but for any given setup, the more voltage you give it, the more current it will use. I like the idea of using 12 volts because it's just a safer, lower voltage, but it may force you to have to use larger electrodes to get the desired current.

                    The curse of having precise measuring tools is being able to actually see how imperfect everything is.


                    • #11
                      Judging from the size of the zip cord relative to the variac, I would hazard that the variac is between 200 and 400 watts rating, probably good for no more than 3-4amps when set at max voltage, with mild deratings for lower voltages. It is a very good idea to fuse the the variac input and not a bad idea to fuse its output. Keep the variac for other uses, get a 12-18-24v
                      transformer rated at 10 amps for the electrolysis work. sells or sold a 24v 10amp transformer for $18 for several yrs.

                      Addendum: On arriving home and checking my variac, which is very similar in size I find it is rated at 1KVA, I thought it was 400-500 watts, so yours is probably good for 8+ amps in the upper voltage range dropping down to 5-6 amps at low volts. I have a couple of 1.5kva variacs that are 12-14" in diameter and 7-8" tall and one that is fist sized that is about 0.15 kva and I was interpolating.
                      Last edited by sch; 09-09-2006, 11:11 PM.


                      • #12
                        OK, I'll do something else.

                        Thanks for the info and warnings. I'll put this variac back on the shelf and start looking for a cheap battery charger. Sounds a lot safer.

                        Originally posted by CCWKen
                        .....Oh, and one more thing. Use rain water or distilled water only!....
                        I live about 40 miles N.E. of Dallas. Is this "rainwater" comment supposed to be a joke?


                        • #13
                          This all looks very cool.

                          If I may ask, what kind of "cleaning soda" is everyone using? Just baking soda or other? And any good local sources for phospheric acid? I actually need some of this for a much larger cleaning project. I believe it is the active ingredient in our acid based EDM cleaners (AC500 and such) but I'm not sure.



                          • #14
                            I use washing soda...get a big box of it from Wal-Mart for under $5 Cnd.
                            I don't use rain water either...just use tap water (with the usual additives).
                            It works fine. Rain water may work better but I can't be bothered.
                            Besides, the last rain we had was very early in July
                            I have tools I don't even know I own...


                            • #15
                              A look at derusting topicals at Home Depot/Lowe's will probably turn up one with phosphate in it. In my experience the phosporic acid is optional at least to the derusting process, and only adds a passivation layer. The washing soda is not the only electrolyte you can use, sodium bicarbonate will work or Na(TSP) for that matter but washing soda is usually available in the cleaning supply area of large groceries or hardware stores and is the default electrolyte. Washing soda is sodium carbonate. Adding phosphoric acid results in bubbling off of CO2 and formation of a sodium phosphate solution with varying amounts of H appended (NaH2PO4, Na2HPO4 or Na3PO4 depending on the final ph.