I kind of wonder where you get Gel Cells in 12 volt or big six volt formats, Kind of rare
NO, Gel's are not good for RV use, They are the fussiest of batteries, Need very tender loving care when it comes to charge and electrical maintenance.
That said: Many people call AGM batteries GEL (I say that because I have seen it happen right here on the forums many times)
AGM's are about as far from GEL as you can get.. Though they share some features.
Differences: IN a GEL battery the electrolytic is a gel, kind of like jello, But like Jello it can still flow a little, Very very slowly, but if the plates push againste it it moves out of the way. AGM's use a fiberglass mat, that "Absorbes" the liquid electrolytic, (Absorption Glass Mat or Absorbed Glass Mat = AGM) this is not as "Giving " as the Gel is if the plates try to move, makes a battery that can take more physicl abuse.
GEL, is, as I said, the fussiest of the big 12 volt or big six volt (Big being more than 10 amp hours) formats, AGM, The most forgiving when it comes to re-charge.
Common feature: IN both cases the battery can be mounted on end, on it's side, upside down, cockeyed, no "This side up" label.
OPTIMA batteries are not GEL (I have seen people her ecall them Gel) they re AGM, sprial wound, and are also a bad choice for house batteries due to the fact that they have sixty percent of the capacity of the same size AGM or "Other" type.
This is due to the shape of the cells, by the way 73 percent is the therotical sice of optima but per the battery company web page. 50 percent is all that is there.
Example: Group 27 Standard, (Flooded wet, maintence free or AGM) about 100 AH.
Group 27 Optima: 60
My recommendations: 1: Avoid GEL
2: If easy access for maintenance (Cleaning and watering, Distilled only please) Flooded wet cells, If and only IF you have the room GC-2 (Golf Car) batteries from Sam's Club may be the best Bang for your Buck.. If access is an issue then:
If mounting is a problem then: AGM.
Home is where I park it!