What about this to replace 3ea 12 volts?

[scottma]

MK Battery 8A8D, 12 Volt, 265 Amp Hour, Sealed AGM Solar Battery

Detailed Description These are completely sealed, absorbed glass mat, valve-regulated batteries with efficient recombination. UL Recognized components to UL MH17218. AGM batteries are recommended for battery backup standby power systems where batteries are in float service with occasional deep discharges. They can operate at temperatures from -40 to 140 F. Delivered from one of 20 MK warehouses across the US.
Volts
12

Terminals
T975

Capacity (Ah)
245 - 257

Dimensions (in) L x W x H
20.8 x 11 x 10

Weight lbs
161

The Benefits of a MK AGM Battery

Sealed Absorbed Technology:
- Completely sealed; valve regulated battery with efficient recombination.
- 250 quality control checks through ISO 9001.
- UL recognized components MH17218.
- Rated non-spillable by ICAO/IATA/DOT.
- Forged terminals and bushings assure no leakage.
- Tank formation ensures voltage matching between cells.
What do you see as the pros and cons?

[Hitchhiker]

Would they be as durable as a wet cell considering they are recommended for battery backup standby power systems where batteries are in float service with occasional deep discharges? Some MH usage styles may involve frequent deep discharges, however yours may not.

[Gary RVRoamer]

You should be able to put 3 x Group 27 12v in that same space and get about 315 AH. Choose either flooded cell or AGM batteries, depending on your preference for maintenance and venting. Lifeline makes a great 12v AGM in Group 27 size; so does Trojan. Or pick a much less expensive flooded cell deep cycle such as the Minnkota size 27 trolling motor battery from Johnson Controls.