First, we had a Heart 2500/130 charge which we've replaced with a MasterVolt Combi unit. The Heart put-out 60-65 Amps maximum actual capacity. The MasterVolt is supposedly "rated" at 200 Amps; but, in the real world, it actually puts out 130-135 amps. This is due to the internal heat generated within the charger itself. (and, it's not that related to external temperature, within reason). You need to make sure the charger is in a relatively normal ambient termperature (NOT THE ENGINE or some other SMALL COMPARTMENT, for example).

Secondly, we routinely bring the batteries back to above 90% capacity when crusing. By design we seldom let the batteries below 55% discharge before we turn-on the generator or the engine. (Our engine has a Balmar 250 amp (nominal) alternator. That's puts out an actual 130-180 amps in it's engine room situation. Less in hot weather because of derating from internal heat. We have a "smart" regulator on the engine too.

Thirdly, we plug-in or run the generator to bring the batteries to full capacity often. In a marina, we will routinely flip the battery off and on to force it to go into a short "Bulk" cycle on occasion.

I realize that many people on moorings or who cruise extensively just don't bring their batteries up to voltage. BUT, that approach will deminish lead acid or gel cells MORE QUICKLY than AGM's. It just can-be less expensive to replace lead-acid batteries. It's not that lead acid batteries don't work; however, you need to have ventilation, maintain their voltage, and when they fail you have the potential for a lot of rotten egg smells (or worse). My other problem is that you really can't routinely bring them back-up to charge quickly and easily

When we originally got the boat, the house bank was drawn down to to "dead" several times. (Charger wasn't turned-on and the refrigeration drew down the batteries over a week.) Someone suggested "equalizing" them because I didn't realize that the resting "full" voltage was about 12.8-12.9 volts. I think trying to "equalize" is something that should be avoided. Anyway, I replaced that bank after A couple of additional "dead" discharges because the shorepower was disconnected by someone over winters and I hadn't turned-off the inverter (which caused a greater background draw). That bank of four 4-D's were replaced after 6 seasons of pretty heavy use because I didn't want to take any chances.

The second bank lasted 7 seasons before I replaced the set. Again, it wasn't because any of the batteries "failed", I just felt that I didn't ant to have a problem while cruising or an extended trip to Southern New England from Annapolis.

I then decided to "cut" or charging time by going to a battery charger that had more real world charging capacity for our 800 AH house bank. In upgrading I went with Mastervolt, largely because I understood that their "ratings" matched their real world output. Without going into that, IT ISN'T SO. But I am happy with the Mastervolt anyway (even if disappointed in their misleading "rating WHICH IS THE SAME AS HEART/XANTEX, etc.). I was also concerned because Xantrex had stopped supporting the controller sytem which I had.

I replaced the house bank at the same time, after 7 uneventful years. I got another 4 Lifeline 4-D's. This time I replaced the Optima engine start battery (after 13 years, just because I didn't want a problem); and I added a dedicated Optima generator start battery instead of simply starting the generator off the house bank.

I think that if you're prepared to maintain quality lead acid batteries and your boat is really designed to allow their operating environment to be ventilated and cool enough, then for some sailors they be cost effective and provide the service you need. However, if you don't, then you not good things could happen. Generally, I think that if you treat them within normal use, the AGM or gel cells are safer and work better form most cruisers. If you can actually charge them reasonably, then gel or AGM batteries are really superior, safer, and probably more cost effective.