Because of my work rotas, my ed regularly sits for 2 weeks at a time, often for 3 weeks parked in an outdoor compound without any problems. If your electrics are in good shape, yours sould do similar. Give it a good run every 2 weeks or so, or get a maintenance charger on it some how.
That said, I did have a new battery this autumn, changed it as soon as the original showed any sign of hesitation on cold startup.
I've other cars that stand a bit, a boat and scooter too, and i use Maplins solar trickle chargers/conditioners to keep the batteries in reasonable shape, for longer. You can get a reasonable quality item, about 0.5 A i think, for about £25 when they are on offer. Dont bother with the real cheap ebay tat, they don't last... especially with the solar panel outdoors 24/7. Mine all have lasted several years, even on the boat near salt water. They will charge ok with the panel inside the car, if you're worried about security, but try to get thepanel aligned properly with the sun once you've parked up. That makes a massive difference to output from the panel.
Some how i don't fret as much with the battery not connected ti the mains permanently, and of course mains is not always doable.
I did use a solar charger on the ed originally, but now not needed.
