Gel: Dead at the tender age of 4

Paul,

To the best of my knowledge, the Remco battery would be an AGM and not a gel battery.

They only make one 12 volt, 80 A/h battery and it is listed as an Absorbed Glass Mat construction.

As far as the life you got out of it, 4 years is not all that bad, but I suspect you have "killed" it. Running it for 3 days until the fridge cuts out sounds like you let it run down too far before re charging it. A battery should not be taken down below 11.6 volts (30%) too often, or it will develop excessive sulfation on the plates.
Sulfation resists the ability for a battery to receive and hold a charge.

As for a replacement AGM.
The most cost effective AGM battery from my research is the REMCO. They can be bought from any Whitworths Marine store.

X-Cell brand.....EBAY.....You are asking for trouble Paul.

Bill.

Paul,
unfortunately you killed your battery...
""she used to run the fridge, lights and the inverter for 3 days BEFORE the fridge would cut out""

To get 3 years out of any battery under the conditions you nominate, I would only (strongly) suggest you get another Remco battery !!

Mainey . . .

one of my batteries is a Remco 110a/h.

Had it three years.

So far so good
(now I've cursed it, look out for further updates)

"many fine cracks in the case.has dried out at the neg end"

As well as the deep discharging, Sounds like its been living in the heat under the bonnet, and the charging current has been unrestricted. Remco tell you that charging current should be limited to no more than 24 amps for your battery.

Remco info here"