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Re: (ET) desulfator
On 17 Feb 2007 at 17:50, Neil Dennis wrote:
> My, My, that was quite a reaction (;-').
Sorry, I don't mean to be overbearing about this. I've posted comments
about desulfators many times before here, though, and didn't really say
anything especially different this time (though I said it perhaps more
succinctly or more bluntly).
Let's try it this way.
Suppose you're down by the dock, cussing about your boat's battery. It's
a
few years old, and you're finding that it won't run the lights long
enough.
It's supposed to be a 120 amp hour battery, but you can use only about 30
amp hours before the lights start getting dim. If you try to run the
trolling motor, the lights almost go out, and the motor barely runs.
I walk by and hear you complaining. I stop and tell you, "You have a
sulfation problem. I have a gadget that will fix that. This is a
desulfator. It reverses sulfation. It can recover some of your battery's
old zip - not all of it, mind you, but some. Now, if you'd been using it
from the time the battery was new, your battery would still be almost like
new. Use it on your next new battery, and when it's this old, it will
still
be good enough to run your lights and motor."
It's a deal. I leave with $69.95 in my pocket, and you have a nice little
black box. It has an AC cord and a wire with clips for the battery.
There's a little blinking LED on it.
I told you to hook this black box up to the battery and leave it plugged
in
for a few days, to get back some of the tired old battery's capacity. And
when you get a new battery, you should use it for 12 to 24 hours about
once
a month, to keep the battery in tip-top shape.
So you try it. Lo and behold, you run it for 3 days and you now have 40
amp
hours. You run it another 3 days and you have 50 amp hours. Another
week,
and you're up to 60!
Ah, but it doesn't last. A month later you're back to 25 amp hours of
capacity. So you bite the bullet and buy a new battery. This time, you
hook up my gadget once a month for 24 hours, just as I suggested. When
this
battery is 3 years old, you have almost 100 of your original 120 amp hours
of capacity. It works!
What did it do?
In a brand new battery, not all the cells are exactly the same. There's
always one that has a little less capacity. Each time you charge the
battery, that's the last one to get full. Sometimes it doesn't quite get
there. If this happens too often, that cell really does begin to develop
permanent sulfation, but that's not what kills it.
The capacity of your battery is determined by that weakest cell. When
that
weak cell goes dead, its electrolyte is essentially water. Its internal
resistance goes way up. Even if the other cells still have some charge
left, they can't push any decent amount of current through the resistance
of
the dead cell. So you can't get much useful work from the battery. But
many times you keep trying to use the battery for a while. It can still
light the lights for some time longer, even if dimly.
When you do this, you're forcing current through that dead cell. This
charges it backwards. This is called cell reversal, and it's very
damaging.
Repeated reversal is what really kills the cell. Its capacity takes a
dive, and now you have a 30 amp hour battery when it used to be 120 amp
hours.
When you connected my "desulfator," it forced current through the good
cells
(in the right direction!) to give the bad one as much charge as it could
possibly hold.
You also helped the battery yourself, just by taking an interest in it.
You
cycled it more often than you usually did. Exercise for batteries is like
exercise for humans - it improves their stamina. This helped to
temporarily
build up its capacity. That's why it rose from 1/4 to 1/2 its new
capacity.
But then you went back to your old usage patterns, and the battery went
back
to its old capacity.
In using my "desulfator" on the *new* battery, you were performing a
regular
equalization on the battery. This kept the inevitable weak cell fully
charged, preventing it from being reversed as frequently. You kept the
battery fit and useful longer.
So I sold you a gadget that fixed your "sulfation problem." I told you it
would reverse sulfation - and it did. I told you it would give your
battery
more capacity - and it did. I told you it would keep a new battery fit
longer - and it did. You're happy, and I'm $69.95 richer. What's the
problem?
What I sold you was a battery charger with a blinking LED. Did I cheat
you?
No. I said it would reverse sulfation, and that's exactly what a battery
charger does - that's how a battery charges. I said it would add some
capacity to your old battery, and an equalizing charge applied with a
battery charger will do that. I said it would help a new battery last
longer, and equalization applied at the proper intervals will do that,
too.
Equalization brings up weak cells to get the maximum possible capacity out
of an old battery, and prevent damage to weak cells in a new battery.
I didn't make any claims about "crystal resonance," even though some
desulfator adherents try to do that. Here's one example : "A desulfator
works by creating a resonance frequency that cause the sulfur ions in the
batteries to dissolve back into the electrolytic solution of the battery."
An electrochemist - an engineer who designs batteries - will tell you that
such claims are nonsense. I suspect that the people who developed pulse
desulfators years ago found that they helped batteries, and they groped
around until they found something that seemed to explain (at least to
their
satisfaction) what the gadgets were doing.
Desulfators have a small but very avid and vocal corps of believers. And
they are right, in a sense - the gadgets do work. But so would a cheap
little trickle charger, for about one-third the price. Or the charger you
already have.
What I really sold you back there on the dock, for $69.95, was $19.95
worth
of charger and $50 worth of advice - that equalizing your battery
regularly
would maximize its capacity and keep it healthy.
But you could have gotten that advice for free - right here, in any number
of good battery books in the library or at the bookstore, or on the web.
I sold you something you could have - should have - gotten for free. Am I
a
crook, or an entrepreneur?
For years I've been asking folks who sell desulfators, and those who are
sold on them, to perform a real test. I want them to use two batches of
essentially identical batteries, applying the desulfator to half and a
decent equalizing charger to the other. Treat the batteries exactly the
same except for what's charging them, and see if one group behaves
significantly differently.
I think that's a reasonable request. It isn't 100% conclusive, but if
their
desulfator is really better than an ordinary charger, it should show up in
statisically significant, consistently improved performance in the group
treated with the desulfator.
So far no one has taken me up on it. Any idea why not?
David Roden - Akron, Ohio, USA
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