On Mon, 1 Jun 2015 10:58:48 -0400, "Tom" wrote:

I have a half dozen marine deep cycle batteries.

Battery manufacturer and model number please? I want to get a clue as
to the size and weight to determine if they're quality or junk as well
as whether there's a sump at the bottom to catch the flaked off
sulfates. Also, what is your use for these batteries and approximate
load requirements?

I get about 8 years
usefullness from them when I store them properly, I slow charge them once
per month while in my garage for winter storage and I try and never leave
them sitting without being charge. I try to never drain them completely, I
keep them filled with RO water and don't over boil them. Etc etc etc.

Many "marine" batteries were NOT designed for stationary use. The
motion of the vessel (or automobile) agitates the electrolyte, which
helps remove surface sulfate accumulation. The "marine" batteries may
also have been designed for starting service, as in an automobile or
vessel, which is quite different from stationary service, such as a
home solar power system. Just about everyone who has built their own
solar power system had tried using cheap automotive batteries which
fail after a few charge cycles. Then, they graduate to the somewhat
better "marine" grade batteries, which fail after a few more charge
cycles. Eventually they go to batteries designed for stationary
service, such as those made by Trojan Battery.
http://www.trojanbattery.com
At various radio sites, the requirement are even more difficult, so
large flooded "telco" batteries are used:
http://members.cruzio.com/~jeffl/k6bj/K6BJ%20Repeater/slides/Batteries.html
Note that these batteries are over 30 years old and still running at
about 90% of their original capacity.

My question is about de-sulfating.

I can't help you with desulfation. I've tried a few random gadgets.
None of them worked for me. So, I gave up.

What I want to try is replacing the sulfuric acid.

That will do next to nothing useful. Lead sulfate is normally
produced during the discharge of a battery. What happens is that
during recharge, some of the lead sulfate does not get converted back
into lead and sulfuric acid. By adding overly concentrated sulfuric
acid to the electrolyte, you prevent the remaining lead in solution
from being replated to the battery plates. You would do better adding
water, which is what is commonly done. When the battery is NOT
agitated, it also creates lead sulfate through stratification. Some
details:
http://www.progressivedyn.com/battery_basics.html

More reading:
http://batteryuniversity.com/learn/article/how_to_restore_and_prolong_lead_acid_batteries


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558