Hi Anton, sorry I missed your reply.
The seller was using them as a slave load for generator testing. He would run them to test (like industrial 10kva stuff) and charge the system and then run his whole outdoor office with them.
They have done about 3-400 cycles so still loads of life.
As for what bits will come out, I'm not sure. The latest idea about Iceland is to go in the Nissan Patrol. Which means using 12v stuff. So some of it may get used. I think I will keep everything until the build is finished and then I understand what I don't need/can't use.
Latest Vlog is here. Checkout the UK premier Overland/Expedition show - I did a terrible job of viewing/filming it. But you get a flavour.