Critique proposed solar battery upgrade

BFL13 wrote:
People seem to like their AGMs but I am not a big fan. There are two in the truck camper because Flooded batts cause fumes inside where the batts go. No choice except AGMs there.

They do well for having little voltage sag under high inverter loads. What I don't like at all is not being able to tell when they are truly full after a recharge except at home after a camping session. You need to observe their amps acceptance when they reach spec voltage, but you can't do that while camping because they always have a draw on them from the RV.

With Flooded you can tell by using an hydrometer. This only matters if you spend a long time off grid without getting shore power so you can operate the RV on converter with the batts disconnected. Now you can do the amps observation on the AGMs to make sure they are truly full and won't get sulfated to death so soon.

For long periods on solar only, where you often go long periods on incompletely charged batts, IMO AGMs are worse than Flooded for being able to keep them from sulfating, because with the Floodeds you can tell what state they are getting in.

BTW, I have tested my AGMs for voltage sag against Trojan 1275s (both deep cycle 12v) and found the AGMs did slightly better per AH of capacity, but not enough to matter.

IMO, T-1275s are the way to go for most RV situations, but you can also get by with all sorts of other set-ups, AGM or not.

One thing that does concern me with AGM is I imagine I'll need to change my converter, from what I heard AGM doesn't like high voltages and a converter that has a profile for AGM is the way to go. Taking that into consideration, I wonder if the added cost doesn't kind of eliminate any advantage I'd get from in switching from FLAs.

Now, if I was to take the cheapest path possible: my existing 4 T125's still hold charge well, don't usually dip below 12.0v for any extended period (they do dip to 11.4-11.3 under inverter load for a few minutes when making coffee, but rise back up), can I get away with just adding a new pair of T-125's? The existing bank are 4-5 years old. I'm psychologically prepared to swap out the entire bank (best to have all new batteries), and I can get some money back by reselling the old ones, unless someone really wants to talk me out of it.