Lots of well-intentioned advice in the above posts. Some of it is IMHO right on the mark. Some misses the mark -- by a wide margin. Some is just plain wrong.
Let's start with basics.
1. A 560AH battery bank is ample to handle your daily usage (~110AH). No problem there.
2. Your present bank has lost
a great deal of capacity. You didn't say how you measured capacity, but if your figures are anywhere near correct it is time to replace the battery bank.
3. Flooded lead-acid batteries are the best bang for the buck for most boats. BTW, flooded, AGM
, and gelled batteries are ALL lead-acid types.
4. How you treat your new batteries will determine how long they will last, i.e., how long they will retain sufficient capacity
for your needs.
5. All batteries begin losing capacity when they leave the factory. New batteries can vary enormously in measured capacity, and none of them reach their design capacity until after several cycles (discharge, recharge and, for most, equalization).
6. Batteries lose capacity thru a number of mechanisms including sulfation, stratification, corrosion
, plate damage, contamination, and others. The most important of these is usually sulfation, i.e., the formation of lead sulfite crystals (PbSO4) on the plates. Left there for long, they will embed themselves permanently in the plates, limiting the area available for electro-chemical processes and, therefore, capacity of the battery.
7. The best way to protect against sulfation is to fully charge the batteries as often as possible.
With many batteries, it's also necessary to equalize them periodically, applying a voltage of 15.5VDC or greater for several hours. You shouldn't do this too often, as each time causes a bit of deterioration of the battery, but it is a necessary step for many batteries.
8. Simply maintaining batteries at a float level of 13.2-13.8VDC will not, in and of itself, prevent sulfation and loss of capacity over time. You really do need to step up the voltage occasionally.
9. "Two 40A chargers" really is unlikely to cut it, unless they are specifically intended and designed to work together (like two identical Iota
DLS-45/IQ4 chargers). If they're not, then one will be fighting with another and you're very unlikely to benefit from their total capacity. Much better to have a single
80A or better charger
. With your onboard generator
, a charger like the Iota
DLS90/IQ4 might be a good solution -- it puts out a genuine 90A or more for as long as is required. And, it's particularly tolerant of generator-provided AC.
10. A larger alternator or a second alternator -- both with external smart regulators -- might be useful, but would be costly in either case. If you're motoring a lot, the existing alternator with a smart regulator should be easily capable of handling your 110AH daily battery draw.