No announcement yet.

Sulfuric acid loss due to boil over

  • Filter
  • Time
  • Show
Clear All
new posts

  • Sulfuric acid loss due to boil over

    Something occurred to me while trying to get my SG up to the specification of 1.275

    When batteries are equalized or overfilled then charged the electrolyte solution spills over the top and out of the lids. From what I understand there is an initial amount of sulfuric acid added to a new battery. So if it spills over the side and is replaced with distilled water doesn't this dilute the sulfuric acid enough to give us lower SG readings over time. Maybe I'm misunderstanding the chemistry here because the SG gets higher and lower with the SOC and the amount of sulfuric acid isn't altered during a normal charge.

    Why I'm thinking this is because I could be wasting my time trying to bring my SG up from 1.240 to 1.275. Or even damaging the batteries having them get hot and bubbling 105F for hours. Obviously my batteries are probably a little sulfated, but I would be curious to know because I help others in my off grid community. Some people have brand new FLA some 2,4,6 years old.


  • #2
    They should never spill over if serviced correctly, only of they have been overfilled with water and yes that will cause issues long term.

    If they are getting hot and not getting up to a decent SG then they will probably be on their way out and from your other thread it sounds like they are not getting charged well because of a lack of sun on panels.

    For long life you want them kept as charged as possible and recharged as quickly as possible when they are down.


    • #3
      Thanks again Bala!

      My batteries are 3yrs old and have been walked down for two years by the previous owner. I have no doubt there is some capacity loss due to the chronic under-charging and this is why I'm seeing an (increased internal resistance?)

      Another thing I'm noticing is after a month of charging, when the electrolyte is about half way down, and still above the plates. I have no problem getting SG readings as high as 1.280. I believe this is due to a more concentrated sulfuric acid solution?

      I'm reading on another forum:

      sorry if it's not allowed to post this here?

      The whole deal with adding acid, flushing batteries, and trying to salvage batteries is a waste of time. There doesn't seem to be a way to know exactly how much sulfuric acid is in each cell. If I'm understanding the chemistry correctly? The sulfuric acid goes into the plates when a battery is fully discharged. If there is sulfation then it will be locked into the plates (internal resistance?) This would be why a sulfated battery has low SG readings.

      All very interesting stuff, to me I guess! I'm a little obsessed I know.