What brand of AGM?
Generally, converters do not excel at feeding any given battery all it can accept during limited generator run times.
AGMs tend to be lumped together as to their charging requirements but they actually vary widely as to what the AGM manufacturers want and recommend for best life and performance during the lifespan of their batteries.
For example some lesser $$ AGM's say to limit Amps to NO MORE than 30 for a hundred amp hour battery, while Odyssey says when their battery is deeply cycled, Feed their Hundred amp hour battery No LESS than 40 amps initially until 14.7v is reached and then 14.7 is to be held for 4 hours or until amps required to hold 14.7v fall below 0.5amps.
Lifeline AGM basically says to Feed them as much amps as you can muster but do not exceed 14.4v and terminate charge when that 100 AH battery needs no more than 0.5a to hold 14.4v
So trying to find the converter which best fits your AGM's is not just a Powermax vs PD vs Iota.
In come the frontal lobe chargers, or adjustable voltage power supplies which have gained favor with many of us. We choose an end voltage and the power supply feeds the battery all it can provide and as much as the battery can accept at that voltage, until battery voltage nears that end( Absorption) voltage.
COnverters suffer from 'premature efloatulation', dropping voltages to 13.6 or 13.2 well before the battery is done accepting what it wants at 14.X as as such, recharging slows to a crawl, while you waste gas and annoy everything around who can hear or smell your generator.
And here you will get those who love to proclaim how quiet their generators are, or that nobody is around anyway, and bla bla bla chest thump, and their system works 'just fine' and their batteries last years and years in their quest for approval of their methods, without realization or care that everyones needs, uses, and desires differ.
Beware of "just fine!". Often it is synonymous with "has not failed yet". Often it means " I have no real Idea, nor do I care, and you should do the same".
This 'Premature efloatulation' is fine when one has a power pedestal to take as long as needed to shoehorn the last amphour back into the battery, but on a generator it is a whole different game.
There are a lot of ways to skin a cat, and no one right way for everybody, or every cat.
I choose to have a 41 amp adjustable voltage power supply( MeanWell RSP-500-15) for when I have ~120 vAC available, 198 watts of solar does the majority of my recharging, and I make sure my alternator is not limited by thin cabling between it and the thirsty battery and I do not fear letting it feed either battery 75+ amps upto the 14.9v my vehicle's voltage regulator allows.
I have one of those hungry AGM'S that loves huge recharging currents, and I only Deep cycle it when I have enough miles to drive or AC available to feed it 40+ amps, and I mostly cycle a single flooded battery to 35 to 50% or deeper the rest of the time. 11.25 out of 12 months a year and likely more than 27 out of every 30 days, continuously.
And it works, "just fine :)"
