Of course, many of us just go with what we've got until we are able to make intelligent upgrades, but the cost comparison between AGMs and flooded batteries is very complicated and I don't think we have all the empirical data needed to make a valid comparison
Thanks for your comments. I agree I would LOVE to have a larger Alternator, and it is really called for with the size of mine and my mates battery banks. Is why I am considering the solar cell to take some of that time away passively.
I used to have the standard 30amp Hatachi which came with my 30hp Yanmar. Anything over 80 amh alternator would require a serpentine basically and a 150 alternator would - not fit oin my engine configuation and 2- drawn to much hp off my small hp deisel Yanmar. I too have the Victron. I would love to have the 150 alternator as you mentioned and put the charge in more quickly with less time on the alternator.
The most I have driven down my battery bank was 3+ days of non-replenishement and showed I had used 240 ah (420 ah left or 64% capacity left) of the 660 ah bank. When I motored for 3 hours the Victron was stating I was placing almost 75 ah back into the banks till I hit 580 ah ( about 85% capacity) ( It was a cool day so the temp sensor didnt slow down the alternator rate. ) At the 540 ah mark the rate the batteries accepted was considerably less at 30 ah. It took 3 hours total to get to 580 where I was aiming. In the same period of time it took my friends 5+ hours.
My point in all this is that the wet cells because of their acceptance rate kept the same alternator and engine running almost 2 hours longer which costs money and of course eats into the lifespan of the alternator. It is a hidden cost of the wet cells which is not measured when looking at the initial price differences between agm and wet cells. MOost people are aghast at the price of the agms and steer away, when in the long run if they built their whole electrical systems better they would actually save.
One of the things I learned a few years ago is that this electrical think is something which I needed to monitor more closely and now I am kind of a hawk about my ah, and battery banks and monitor quite closely. Going through a set of wet cells convinced me that if I didnt I would literally pay the price again and again.
Sigh...things were far simpler with the hobie cat or first keel boats with 2 group 31 and only occcasional overnight sailing. But then again no refrigeration, not chartplotter, no shower pump or pressurized water, no solenoid for propane, no inverter...g,d...how did I ever survive
Bbut the Admiral is far happier and wants to go out all the time so we now travel in "style" now with al the lectrical stuff.. A willing compromise.