MacGregorSailors.com

Opie thanks for the encouragement to investigate my batteries further. Below is taken from the Trojan website. I was kind of amazed that it said 80% is the maximum safe discharge. But at the same time in the line above it says 50% or less discharges are recommended. As stated above we consider 65% battery level as the lowest before recharging.

Shallow discharges will result in a longer battery life.
50% (or less) discharges are recommended.
80% discharge is the maximum safe discharge.
Do not fully discharge flooded batteries (80% or more). This will damage (or kill) the battery.
Many experts recommend operating batteries only between the 50% to 85% of full charge range. A periodic equalization charge is a must when using this practice

Below is the info from Trojan on equalizing batteries. It appears that Equalizing and Desulfation of batteries are the same thing.

Many experts recommend that batteries be equalized periodically, ranging anywhere from once a month to once or twice per year. However, Trojan only recommends equalizing when low or wide ranging specific gravity (>0.030) are detected after fully charging a battery.
In another place they state that batteries in a solar system should be equalized once or twice per month.

I do not own a hydrometer. Most likely will purchase one. But for now as Be Free says "if it aint broke don't fix it" so we will continue to equalize as we have been doing. Most likely we will do it on a yearly basis from now on. Batteries might be like impellors in an outboard water pump, the more you use them the longer they last, if used correctly. We use our batteries daily on our 6 to 9 month trips. Once again you folks as a group have a lot of knowledge. I spend a lot of time researching stuff but I was not up to snuff on this battery stuff. I was doing what someone told me without research fortunately it was the right info instead of internet blather. Also want to mention again that the Equalization/Desulfation is a mode on our Sterling battery charger that we move from boat to trailer.

If you are bringing your batteries back to a full charge on a regular basis you will not get a lot of sulfation and can probably get away with equalizing less often. Where it becomes critical is when you are not getting them back to 100% charged on a regular basis. Leaving your batteries partially charged on a regular basis will shorten their life. Leaving them fully discharged is often a death sentence.

Lead acid batteries will charge up to (around) 80% pretty fast if the charger can provide the charge they are willing to accept. The usual target charge rate for this first phase is around 20% of the AH capacity of the battery. Even if your charger can't hit his rate this will still be the fastest part of the charge and it's the best time to hit is with all the "big guns" in your charging arsenal. Using shore power, a generator, or perhaps the alternator on your outboard will get your batteries charged quickest at this point.

Most of us will have our batteries most discharged first thing in the morning so even if you have a large solar array you may it may not be generating enough power to help (much). Throw everything you have at it when the batteries are most discharged. You can't mix generator and shore power on the same circuit but your batteries will happily charge from multiple sources simultaneously if they are available.

If you have solar, wind, or water generator available that will usually work best for the last part of the charge. Fully charged batteries are happy and healthy.