Conclusion:

While I learned that some flooded cells have a superior cycle life, AGMs are still the battery in my future. I do not enjoy battery maintenance - I prefer to sail - and there are so many additional benefits to using AGMs over flooded cells. Since our boat already has a powerful charging system, the next logical step is to install better batteries to take advantage of it.

Thus, our battery compartment saw a refit and expansion in order to house 6 group GPL4C AGMs by Lifeline to replace the 3 group 30H batteries there before. The diesel engine is now totally "over-batteried" with over 900CCA while the house bank grew from 260 to 400 Ah of capacity.

The new AGM battery banks consist of a series configured starter bank (2x6 Volt Cells) and a series-parallel configured house bank (2 sets of 2x6V cells). While the boat is fused with 2 sets of 200A Class T fuses, and the connectors that put the house bank batteries into series also feature 200A fuses. Thus, I can safely combine maximum battery life and performance with much less maintenance.

Remember, battery and charge systems can be very powerful and dangerous. If you are competent enough to read, understand, and follow the guidelines found in marine electrical manuals, you can do much of the work yourself. However, don't blame me if something goes wrong!

Even if you want someone else to do the work, it is always better to understand and know what to look for when inspecting the system. The entire electrical system on board will have to be sized to accommodate the intended loads and charge systems. It is up to you to ensure that whatever changes are made to your system meet ABYC and other marine electrical standards. Good luck on your journey and happy sailing.