"Mark" wrote in news:1156829173.178462.265980
@h48g2000cwc.googlegroups.com:

From a University of Washington paper:

"If plates are exposed above the electrolyte then the capacity of the
exposed plate
areas has been lost and cells will likely develop short-circuits
because of plate shedding. Batteries with exposed plates should be
replaced."

You seem to be saying exposed plate area can be recovered by
recharging. That's apparently not so. I once accidently exposed about
50% of the plate area on a battery, and it lost about 50% of its
capacity; soon thereafter it died due to shorted plates, probably from
plate shedding. Exactly as the UW paper described.



In order to "sulphate", conversion of lead metal into lead sulphate, it
takes sulphuric acid, not air. Lead sulphate is suspended in the
solution of the electrolyte, after it has released its electrons to us.
I don't see how exposing lead to air can eat it away. That's what the
posts are doing all the time, and they're lead.

No, I disagree with the professors, I'm afraid. Using a battery with low
electrolyte eats away the BOTTOM of the plates, sometimes bad enough to
eat holes in them we cannot recover because the electrolyte still has the
same acid it started out with, in a more concentrated form, and the
electronics freed must come from the plates still submerged, eating them
away far worse than the engineers intended. So, if anything is
"damaged" or "unrecoverable" it MIGHT be the submerged portion of the
plates, not the exposed-to-air top, which won't get eaten away
discharging at all. See my point?

It's the submerged part that needs to be recharged very badly, not the
exposed part. But, alas, we're talking of extreme conditions, not the
conditions in your boat. You don't discharge the battery severely, or I
hope you don't. You also didn't let the battery get THAT FAR down in
electrolyte, just a little below the plates, exposing them. When you
submerge these plates, that haven't been holed permanently, with
DISTILLED WATER ONLY, please....The battery will nicely recover, after a
few charge/discharge cycles, to its soft plated old self, the tops of the
plates resoftening by the cycling, like we're SUPPOSED to do to a brand
new battery that's just had its initial electrolyte charge poured into
it. Of course, noone in reality ever does a proper cycling of a new
battery to soften up those plates. That takes too much time from our
busy life. The dealer doesn't do it, either. He pours the electrolyte
pack into the holes, helter skelter, and never checks the gravity again
to see which cells are really hot and which are not-so-hot...caused by
differences and impurities in the plates.

If we had any brains, we'd dump this crap and go back to "Edison Cells",
those Nickel-Iron-Potassium Hydroxide beasts just outside my hamshack.
Mine were made in the late 40's for a telephone system and STILL have the
capacity stamped into the cases....(c; Ni-Fe batteries are only bad for
the battery business....never needing constant replacing and recycling as
Pb's do....the reason they just HAD to be eliminated.
http://www.beutilityfree.com/battery...tery_flyer.pdf
Don't worry about how deep you discharge them. Recharge them when the
lights get too dim...(c; It doesn't hurt them at all. You don't even
need a regulated charger.

--
There's amazing intelligence in the Universe.
You can tell because none of them ever called Earth.