Hi David
just had another recurrence of the grey material .It sounds like a heavy drain to empty your battery in 2 1/2 hours but intermittent. IIRC i had a freelander that would do the same thing occasionally come in to the garage .using an clamp ammeter one day it showed a 10 amp discharge with everything switched off . Eventually traced to a relay which powered an heating element in the inlet manifold to warm the air/fuel mixture when cold . the relay was faulty and occasionally didnt trip out hence a while later flat batttery
jump start car off it went again
took ages to suss that one
Dave