" Adding acid to electrolyte to "rejuvenate" dead cells is SUICIDE!"
The bottle of stuff is sold in most auto stores. It's not my idea. I've
used it before and it works. The lead is not the problem. Its sulfur
crystals formed from gassing and when you add water, the sulfuric acid
gets a little weaker as some of the sulfide stays crystallized.
Shorting just lowers the voltage you can get but it doesn't blow up
batteries as far as I have ever seen. Hydrogen is given off and that
might but crystals don't.

Now as for your view on buying new batteries, I'm right with you. I
buy Wal-mart batteries and they last me 2 years before I dump them.
Even if they are working pretty well, I like really good and easy to
charge batteries. For what I put into my boat, an average of $180 to
$200 a year is nothing.

I've been told by owners that the 6 volt batteries are the best but I
have never liked the idea of losing one and really losing 2. Maybe next
time I will give them a try.

As for the 16.8 volt thing, the majority of high end chargers all offer
that. It can't be that bad can it? I'm still into just buying new ones
but I know people that zap theirs and they say it works for them.