suitable habitation battery for my nuevo,?

I bought my Nuevo ,she is 2003 registration 2 berth, almost four years ago. i have replaced tyres, drainage taps etc. This year I thought I would tackle the batteries. It seemed fairly easy to decide on the engine battery but the best quality habitation has me stumpted. We are usually plugged in and I keep her plugged in through the winter with a greenhouse heater. On the occasions we are not plugged in I need to be able to run certain bits of equipment as my husband is disabled so...fridge ignition,cooker ignition ,lighting and CPAP ( breathing machine I have managed to get 12v conversion ) that runs overnight. He rather likes his talking book as well but that is a bonus.
I am less worried about the price and more concerned about maintenance free capacity.
Advice please!

You are governed by physical size under the driver's seat. Standard for the size is 75 amp but I looked at Tayna online who deliver nationwide and got an 85 amp, the largest available in the size. It is a sealed one so no topping up needed

thanks for this I will look, i guess you are telling me i need to measure the existing battery....is there a particular type I should get ??? I understand the sealed bit. & the amps

Maybe telling you the obvious here, but bear in mind the drivers seat has to be removed to get at the battery. If you've not done it before, it's quite a heavy lump and the front screws can be a pain as the nuts are not captive and are hard to get a spanner on.
Not something you want to repeat too often, so best to measure up and replace the battery while the seat is off.
Al.

It appears that what you need is increased capacity (amp hours). You should consider installing a second battery rather than a replacement, effectively doubling the available amp hours.
I am unfamiliar with the Nuevo but I'm sure someone on this forum will step in with some sound advice. Keith.

From what the poster says, it's only on occasion that they don't have EHU, so I would have thought a new 85 Amp hr battery would suffice. However, before I fitted a solar panel I was looking into fitting a second battery. The most likely places are under the passenger seat, but to my mind this is not a good idea due to having to fabricate a battery box and run wires across the space between the seats. The alternative position is under the bench seat directly behind the drivers seat. Easy access and minimum work to secure a battery and fit short connecting cables.
What put me off doing this is the considerable extra weight of a second battery, a 100w solar panel and regulator on the other hand weigh next to nothing and keep the battery topped up when away from EHU.
Al.

Tanya now have a 100ah battery that will fit under the seat of my Devon. It uses Ca technology so not only is it smaller, but lighter too compared to the large heavy 90ah one I took out. https://www.tayna.co.uk/EXV100-Enduroline-Leisure-Battery-P8705.html

Thank you for the advice.Especially the warning about removing the seat.It is a bit heavy. i shall have a look at the Tanya and go to a garage.I found a lovely garage in Woldingham who fitted my vehicle battery, a BOSCH . Not sure they will get a tayna as they are Bosch agents.nyone know of a reliable service  for habitation and Truma maintenance in the East Surrey , North West sussex ( Gatwick ish) area ?