I recently bought a Cabanon Venus trailer tent which had been stored for some time, perhaps two or more years. In the storage box I found a small sealed-for-life car battery which I thought must be useless after so much inactivity, however as one who prefers to try things rather than chuck them away, I connected it to a battery charger. After 48hrs, there was some life in it but it wouldn't charge up fully. I then connected a small bulb to it and it lit up, and I left this connected up for another 48hrs before reconnecting the battery charger. After a few spells of this, I connected my Optimate II smart charger and after 24hrs it shows a full charge at last.
Now this could all be a waste of time and the battery might still let me down just when I need it but as it will only be used for powering and interior light, I think there's life in the old dog yet.
I have a couple of Optimate IIs which I connect to my motorcycle batteries when left standing for months and these work a treat.
1. But it would never have a decent load, just a small interior light.
1a. I have no way of trying it with a 10amp load.
2. Yes, that would be Stage 2 after I've discovered how much life, if any, I can get out of the old thing. I have a Halfords Trade Card which gives me a hefty discount on batteries and stuff.
The standard caravan lights can be upto 3 amps, stick them all on and thats probably a 10A load. Then put the waterpump on and see what the voltage is like.
Ah, I have a 2-berth trailer tent with a small plug-in lamp, which I have only just bought and have yet to use for the first time. I intend to live simply ;-) I'll see how it goes anyway and it will be a simple job to buy another battery if this gives up the ghost.