(06-04-2015 01:20 AM)GWild Wrote: But having to maintain a wet battery (keep the electrolyte channels full), and that they generally don't have gas recovery caps, means a lot of work.
With my cheap 100 Ah deep cycle wet cell marine batteries, and my Schumacher SE-1-12S charger, I check the water level about every 6 months and probably only need to add water about every 2 years, if that often.
Stop and think how often you have to add water to your car battery.
(06-04-2015 01:20 AM)GWild Wrote: A few bucks more buys an AGM.
Your definition of a few more bucks differs considerably from mine.
(06-04-2015 01:20 AM)GWild Wrote: so a non-sealed LA car battery inside a home on a charger is a bad thing).
If you're worried about hydrogen accumulating in your room, it's unlikely to be a problem. Don't put the battery in an airtight box.
You won't get much hydrogen gas unless you have a bank of batteries or a really high current charger. The theoretical maximum amount of hydrogen a 10 amp charger can produce is about 2 ounces per day. Unless it's in a tightly sealed box, the hydrogen will dissipate rapidly and won't accumulate to high levels in a room in your house.
In practice, it would probably produce much less hydrogen. Much of the hydrogen recombines with oxygen inside the battery, even in an unsealed wet cell.
Also, in order to produce 2 ounces of hydrogen, you have to consume 18 ounces (over 2 cups) of water. Unless you're consuming water at a prodigious rate, you're not likely to have much hydrogen escaping the battery per day.
AGM/cell/VRLA/sealed lead acid batteries do have extra provisions to recombine hydrogen and oxygen, but in some cases, they produce hydrogen and will release it through a vent when the pressure builds up.
(06-04-2015 01:20 AM)GWild Wrote: The method of constant desulfation - the theory anyway - is to use a pulsed DC circuit for controlling charge current during float. Well, most chargers were once analog brute force with little or no control of voltage or current. Then came 'smart chargers' with switching supplies. High current filter capacitors and inductors are expensive, and since a battery has a pretty solid ultra low ESR, these parts are almost pointless unless the exact battery load is known. So why not market the ripple current as a feature?
I recall some tests where it helped, some where it didn't. All depends on the battery construction. In the end, controlling the charge voltage versus temperature has a major impact on battery life, and that's where you want to spend money to get the most out of a set of batteries. That's why you see three stage chargers.
Desulfation is sort of black magic and rumor to me. My impression is that desulfating is very iffy. The trick is to prevent sulfation from happening, mostly by keeping the battery charged. You might try desulfation on a battery that's gone bad from sitting uncharged, but don't count on it to work.