Off to France(again)!I always have two 7kg bottles with me.I use one then when it runs out switch to the second.Never use more than one when we are away for a couple of weeks.Checked this morning and can't remember which is the full one.It would appear that neither is full.One weighs 11.4kg and the other 12.4!what should a full one weigh.Have I got enough between the two??