My 320 has a Varta dual purpose agm battery & as far as I know it’s the original from when the caravan was new in 2017 not that you can guarantee age as the tyres were 2 years old when they built the caravan which of course I binned. I do try to look after the battery but I keep waiting for it to fail. Car batteries an often fail 3 years old depending on their life but a premium Varta dual purpose AGM I never used before and wondered what typical life span people have had. I also add my caravan has a motor mover but I do plug the caravan periodically though out the year

I must have a look at my charger fitted on the caravan as from what I read AGM batteries need the right charger. As I sad earlier I have a 2017 320 which I got the July/August before covid hit and I’m presuming it’s all original factory charger & battery but myself coming from the mainly tyre trade but 40 years ago I regularly used to fill countless tractor batteries up with acid and a batteries life starts when it’s filled & you see them in some caravan places possibly years old & had zero maintenance since they were first filled with acid & maintenance is critical & the big ones aren’t cheap

I have a 2015 Familia 320 with a motor mover from new, the Varta AGM battery is still going strong. I tend to have a 3/3 rule, every 3 weeks I plug the EHU in for 3 days to top up the battery 😊

A van built in 2017 should have a Schaudt CSV402 charger/distribution unit installed. This is the correct charger, and has a setting for, an AGM battery.
My Varta was new in the van when purchased in 2016 and is still (touch wood) working correctly. Like Colin my van is garaged and is plugged in all the time, it also has a mover.

It’s good to know that everyone seems to get a good few years out of their batteries, I was just wondering purely with going up Scotland at some point & wouldn’t want it to fail while I was up there. I do tend to check voltage every so often, not when it’s been on charge though because you tend to get a surface voltage and plug it on charge every 2 months usually.
Many thanks for the feedback

Two things kill a battery. Being discharged and cold weather. The two together are the worst.

When on charge a volt meter will read around 13.8 volts, that's the input voltage from the charger. To get a settled voltage reading, the charger should be off for about 30 minutes to allow the chemicals reaction to settle. A fully charged battery should read around 12.6 volts and at 12.0 volts it's almost flat. Lower than that risks permanent damage, especially if it's frozen.

A 100W solar panel will usually keep a battery in good condition over winter but failing that removing it and putting it on a smart charger. Aldi do one at a good price, will cosset it, or if keeping in the van a day's charging once a month is all that's necessary.

As to battery life, that's a as long as a piece of string question.