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Battery Wisdom Needed

Discussion in 'Home Power and Microgeneration' started by Bob Adkins, Jul 11, 2005.

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  1. Bob Adkins

    Bob Adkins Guest

    I just had a 12v 115ah marine battery go out on me.

    It was charged by a 45w solar panel and a Morningstar controller. It's been
    great for over 2 years. I have only drained it until the inverter complained
    (11v?) 2 or 3 times. I think it had an easy life.

    Over time, every time I checked it after having not using it for 2-3 days,
    it had ~13.9v.

    I recently added water for the first and only time. All cells were equal,
    and about 1/8" over the plates. I added RO water just below maximum. Within
    a week, my previously clean battery began to spit and stay damp with acid.
    After 2-3 weeks, it let me down.

    Under a light load this Saturday, it dropped quickly to ~10v. I let it rest,
    and voltage was still ~10v. Then I applied a bigger load. I boosted a riding
    mower just to see what it would do. After bumping the starter a few times,
    it began turning it over vigorously. I checked the voltage again, and it was

    Wonder what happened? Does this sound like a cell dropping in and out? I
    guess it's a goner, huh?

    I went to Sam's Club Sunday and grabbed a pair of cheap 185ah golf cart
    batteries. All I have for charging them is a cheapie Sears 10a charger. Is
    this good enough for the initial charge? How long should I charge them?
    Until they become warm? (I recently broke my hydrometer!) It's interesting
    that they had a surprisingly high voltage right out of the store... just
    over 7v on each battery. I was expecting 6.2-6.4v tops.

    I keep my batteries an a 20x30 metal building, and I'm sure it gets well
    over 100F for much of the day. I know heat will shorten battery life, but
    will it be a significant amount? I want to build a bench for them, but it
    will probably be 5-10F hotter up at waist level. Should I leave them at
    floor level?

    Sorry for the long post. Any or all answers appreciated!


    -- Bob
  2. SQLit

    SQLit Guest

    I could be way off base and usually am.

    Light loading on a battery is not a good idea, IMO. When I was taking care
    of a battery bank we always discharged it to about 50% of capacity once a
    month. I was told that it had something to do with sulfide build up in the
    batteries. Once I was told to completely discharge it. Put a load on it
    bring it down then do a deep charge.
  3. Bob Adkins

    Bob Adkins Guest

    The RO filtering was done in a dialysis clinic. It's run through water
    filtering, softening, then a big medical grade RO filter. <shrug>

    I have used plain tap water (from the same city water system) and never had
    that happen.

    The electrolyte level wasn't real low. I only topped it off about 1/8" or a
    little more. Maybe 4oz per cell.

    I would think this system would produce the next best thing to distilled,
    and very close. Maybe I'm way off base on that.

    Don't misunderstand. I also suspect the RO water may have had something to
    do with it. But what? If the water was that bad, dialysis patients would be
    dying like flies. :)

    -- Bob
  4. Bob Adkins

    Bob Adkins Guest

    Yea, me too. You can practically disregard everything I say. :)
    Others say that marine batteries will not last long if run down below 80%
    many times. (20% capacity used).

    I did use pretty high loads often, but only for short duration. I guess even
    an 800w power drill on the inverter could draw some pretty hefty amps...
    probably somewhere around 65a.

    When I ran high amp tools, the battery would slowly drain to ~11.5v, and
    quickly recover to the 12.4v range when the load was removed. To me, that's
    a sign of a healthy battery.

    Oh well, maybe it was cheaply made and I should feel lucky to get 2.5 years
    out of it. <shrug>


    -- Bob
  5. Me

    Me Guest

    Not really, Iron in dialysis water wouldn't hurt anyone, but it will
    kill a battery in extremely small quantities. Same with disolved Calcium
    and a few other such chemicals.

  6. JoeSixPack

    JoeSixPack Guest


    What's bad for a battery has nothing to do with what's bad for you. I'm
    surprised that no one cautioned you against using anything but distilled

    FYI, too much distilled water can make you ill or even kill you, by
    gradually removing electrolytes from your body.
  7. JoeSixPack wrote:
    Even small amounts of any kind of water can kill you if you inhale it.

    For what it's worth, I don't believe there is much evidence behind this
    "distilled water can kill you" myth. The trace amount of minerals you
    get in water is fairly insignificant compared to the amount of minerals
    you get in your food. There should be no reason that you should need
    additional minerals in your water as long as you are eating, well, food.

  8. Guest

    That might be true, if you at nothing but refined sugar :)

  9. Nick Hull

    Nick Hull Guest

    How about condensate from an air conditioner?
  10. Bob Adkins

    Bob Adkins Guest


    I know the "experts" and most (but not all) manufacturers recommend
    distilled water. I have used plain tap water on marine batteries that lasted
    for 4-5 years. Why would a single small drink of RO water kill a battery so
    quickly? Maybe it didn't. Maybe it was a cheap battery and it was a
    coincidence it died just after I added the water. Maybe the battery is OK,
    and just needs "shaking up" a little. I'll soon find out.

    I have heard that distilled water is not good for you. I have even heard
    that RO water is "hungry", and can leach minerals from bones and teeth. In
    my opinion, you would have to drink gallons per day to hurt you. But hey, it
    tastes too bad to drink anyway.

    Thanks Joe,,,

    -- Bob
  11. Air conditioner condensate usually has any amount of dust and dirt
    extracted from the air as well as a small amount of metal dissolved
    from the equipment itself.

  12. Vaughn Simon

    Vaughn Simon Guest

    As well as alge and an unknown census of other living things.

  13. JoeSixPack

    JoeSixPack Guest

    You prompted me to do a more extensive search on this question. The split
    seems to be about 50/50 between naysayers and those who warn against
    drinking distilled water on a long-term basis.

    There seem to be a number of studies that suggest you are probably better
    off drinking undistilled water because it contains more minerals and
    electrolytes. The opposition to this idea seems mostly based on blanket
    dismissals and anecdotal evidence.

    Gatorade and the whole category of similar sports-drinks are based on
    replacing electrolytes lost by perspiration. The science of that suggests
    that distilled water would be worse for you.

    Until the science is all in, I'd say it's ill-advised to form any firm
    conclusions about drinking large quantities of distilled water.
  14. daestrom

    daestrom Guest

    One group that habitually drinks distilled water are navy sailors. All the
    freshwater on board ship comes from distilling seawater. Sailors out to see
    for months at a time show no ill effects from drinking nothing but distilled
    water and coffee made from distilled water. But they also have a balanced
    diet of food too.

    As far as sports drinks, yes they replace electrolytes that are lost due to
    persperation. But you could get the same from drinking distilled water and
    taking 'salt' pills (not just sodium chloride, but a mixture of sea-salts).
    This was in fact the regimen for working in tropical climates for many

  15. daestrom

    daestrom Guest

    Probably a small amount of tap water wouldn't hurt it. But try not to make
    a habit of it. 'Softened' water on the other had has many of the minerals
    replaced with sodium chloride. And that would be a bad thing to put into
    battery acid (releases the chlorine as a gas).

    But moving it around can cause a 'sudden' failure. Plate material that was
    shed from the surface of the plates can accumulate in the bottom of the cell
    in the space below the plates (some 'maintenance free' batteries have a
    deeper pocket so they last longer before the build up of shed material
    touches/shorts the plates. But shaking it up and moving it around *could*
    break off some material and short the cell, or stir up the sediments in the
    bottom and cause them to short a cell (or two).

    Guess it depends, how 'rough' did you handle it??

  16. JoeSixPack

    JoeSixPack Guest

    Another group is the one I met in Montana, who live in an underground
  17. JoeSixPack

    JoeSixPack Guest

    It's easier that way, form your conclusions first, so that no science is
  18. Me

    Me Guest

    Only if you piss.......and only over a fairly long term....

  19. Vaughn

    Vaughn Guest

    True but... Actually Navy evaps are not perfect and some minerals remain.
    I don't know what they do today, but they used to analyze each batch. The
    really good stuff was used as fed water for the steam plant, the stuff that
    still had too many minerals went into potable water. By the way, salt pills
    disappeared from Navy engine rooms decades ago.

  20. Bob Adkins

    Bob Adkins Guest

    I say both sides are right.

    It's a matter of degrees. If you don't get enough Ca, Fe, Mg, etc in your
    regular diet, then heavy doses of distilled water could possibly aggravate
    the deficiency.
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