gassing question

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  • mdagli1
    Junior Member
    • Apr 2020
    • 21
    #1

    gassing question

    Hello, do NiFe battery cells emit oxygen as well as hydrogen during charging, or is it just hydrogen only?
    They seem to gas the most at absorption and equalising.

    I've bought some recombination venting caps and seem to be working but I need a little bit more information about the material science around them.
    Tags: None
    • Mike90250
      Moderator
      • May 2009
      • 16020
      #2
      NiFe batteries electrolize water, breaking it down into O2 and H. Recombiner caps would work, but they will be overwhelmed and maybe overheat, because the batteries GAS A LOT. Recombiner caps state to remove them when EQ'ing a battery bank, because the amount of gas released will overheat the catalyst inside.
      It's possible to work, if you have very small batteries and large caps for L16 batteries. Also, the alkaline electrolyte is likely to corrode the catalyst metals in the caps
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

      solar: http://tinyurl.com/LMR-Solar
      gen: http://tinyurl.com/LMR-Lister

        Comment

        • mdagli1
          Junior Member
          • Apr 2020
          • 21
          #3
          How long would the catalyst last if left at float?
          Attached Files

            Comment

            • Mike90250
              Moderator
              • May 2009
              • 16020
              #4
              depends on the battery size and heat. Your guess is as good as mine. The hotter the caps run, the shorter their lifetime. And if electrolyte mist gets into them, they will quickly die. You have them , I guess use them. How often are you adding water, and what sort of hassle is getting caps off to add if you need to ?
              Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
              || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
              || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

              solar: http://tinyurl.com/LMR-Solar
              gen: http://tinyurl.com/LMR-Lister

                Comment

                • mdagli1
                  Junior Member
                  • Apr 2020
                  • 21
                  #5
                  The plan was not to need to add water with the recombiners.

                  ​​​​​​Tempted to add a hydrophilic filter between the recombiner and the vent adaptor to reduce the salt heading towards the catalyst, but still allowing gasses and water to pass...

                    Comment

                    • mdagli1
                      Junior Member
                      • Apr 2020
                      • 21
                      #6
                      Oh, I tell you what I do have is a load of PVDF membranes, but they are hydrophobic... I don't think that should matter though.
                      Will order some more Viton o-rings to hold it in place though. Just to test.
                      Attached Files

                        Comment

                        • Mike90250
                          Moderator
                          • May 2009
                          • 16020
                          #7
                          If it works out let me know, I'm not happy with the battery water system I have now, with 40 caps, one or two, always seem to stick and flood a cell.
                          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                          solar: http://tinyurl.com/LMR-Solar
                          gen: http://tinyurl.com/LMR-Lister

                            Comment

                            • mdagli1
                              Junior Member
                              • Apr 2020
                              • 21
                              #8
                              Hi there, it appears that both PES and PVDF membranes are not porous enough to allow water to pass through under gravity only.
                              Wil̶l̶ ̶h̶a̶v̶e̶ ̶t̶o̶ ̶u̶s̶e̶ ̶g̶r̶a̶d̶e̶ ̶0̶,̶ ̶g̶l̶a̶s̶s̶ ̶f̶r̶i̶t̶s̶ ̶i̶n̶s̶t̶e̶a̶d̶.̶


                              Also, a quick breakdown on how much this project of mine costs to build (excluding sourcing mistakes and shipping):

                              $5.00 USD = 10AH 1.2V NiFe battery cell (from China)
                              €15.00 EUR = 500AH Recombiner battery vent plug (from Poland)
                              £20.00 GBP = 3D printed, Nylon PA12, adaptor for vent plug (designed by myself, made in UK)
                              £0.50 GBP = 13 x 3mm Viton 75 O'Ring (sourced from UK)
                              £0.50 GBP = custom clear label, Waterproof Vinyl (designed by myself, made in UK)
                              £1.00 GBP = POLYPROPYLENE 5/8" solid ball (sourced from UK)
                              Attached Files
                              Last edited by mdagli1; 06-08-2020, 09:45 PM. Reason: changed layout to improve legibility, added sourcing localisation

                                Comment

                                • mdagli1
                                  Junior Member
                                  • Apr 2020
                                  • 21
                                  #9
                                  OK, it appears that the voltage is key on controlling the gassing issue.
                                  1.45V per cell is the settled voltage after an equalising charge of 1.65V which I'm guessing by the endless bubbling of the electrolyte is over charged.
                                  Using some resisters I discharged the cells a bit. After disconnecting, they settled at 1.26V which is about where the bubbling stops.

                                  To stop the electrolyte from creeping up into the recombiner, I put in a polypropylene ball into the adapter as a floating gravity valve instead of a filter.
                                  This should allow gas to travel upwards and water to flow downwards without issue.

                                    Comment

                                    • mdagli1
                                      Junior Member
                                      • Apr 2020
                                      • 21
                                      #10
                                      Hello, been experimenting with a solar charge controller in combination with my 10Ah NiFe cells:

                                      For zero gassing per cell when using recombination plugs on the vents:
                                      Float: 1.3V
                                      Bulk/Absorb: 1.5V
                                      Absorb tail off current: 1.4A
                                      Usable capacity: 50%

                                      For full usable capacity, the gassing becomes unavoidable and will need venting into the atmosphere...

                                        Comment

                                        • Mike90250
                                          Moderator
                                          • May 2009
                                          • 16020
                                          #11
                                          This sounds like a nice thing for a small install, but sadly not too feasible for much larger batteries where full capacity is needed. I've been covered in smoke the last 5 days, and needing to run generator to keep things going.
                                          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                                          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                                          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                                          solar: http://tinyurl.com/LMR-Solar
                                          gen: http://tinyurl.com/LMR-Lister

                                            Comment

                                            • mdagli1
                                              Junior Member
                                              • Apr 2020
                                              • 21
                                              #12
                                              Hello, apparently increasing the atmospheric pressure inside the cells also helps improve recombination efficiency, (controlled with a valve).

                                              Unfortunately, I have bought the RecPlug3 which only has the flame arrester and operates at normal atmospheric pressure.
                                              The RecPlug2 has a Bi-directional valve which increases internal pressure to some level and a flame arrester. I also don't know how well sealed my cells are by design...

                                              Guess this will be my next path of investigation.

                                                Comment

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