Just trying to help

Our other daughters partner, future son in law possibly, is a lovely bloke but he has this enormous, flashy, Range Rover, which seems to have problem after problem.
Latest thing is the battery dying. I said I have a spare battery in the garage and I put it on charge. Johanna called to say she was getting a new battery so it was alright.
When she arrived last night she had this battery that was of equal proportions to the enormous vehicle!! Anyway, Luke was off somewhere so Jo and I went off to where the Range Rover was stranded, removed the gigantic old battery, fitted the new one and it started.
Jo took it to the car park where Luke was at the Gym and when he came out the new battery was dead.
Today the shop exchanged the battery, which was very good of them, and I fitted the new new battery and followed Jo home, me driving her car and she the Range Rover. She got home, about 15 miles away, stopped the engine, realised she was a bit too far from the garage door so turned the key to move forward a little - Nothing, dead again already.
So this is me putting the battery on charge for when Luke gets home this evening. 
Something terribly wrong which is draining the battery, these vehicles are notorious for consuming huge amounts of battery power so it could be the alternator, Earth problem, fuse, who knows.
Luke will investigate.

Edit note - Just noticed I have a 'Julius Caesar' type hair style, looks like a comb over but I promise you it is totally natural!