I can leave my defender 90 td 5 for an hour and the battery will be flat.The fault is intermitent but I have to use a quick diconector every time I stop the engine as I have been caught out several times and have to get a jump start. This fault started a year ago and I was told I needed a new battery. Bought new one, still got massive intermitent disharge and old battery still starting my ford tractor, so Im sure its not battery. Live battery terminal gets very hot and Im afraid of a fire , Have done all the relevant checks for discharge with ammeters and multimeters but when I disconect the negative terminal to do tests the fault is gone .I cant leave connected in fear of blowing up mutimeter. can anyone suggest any thing other than changing alternator and starter motor which is very recent anyway.

No way I would even think about driving that! The positive cable must be chaffed somewhere and rubbing against the chassis. Where it passes through the front of the seat box is dodgy, as the rubber grommet usually comes off. I use a short length of rubber heater hose secured by nylon ties, to insulate the cable at this point. Check the cable along its entire route and protect where necessary.

Yep, you have a short somewhere. Most likely on the live from the battery to the engine. Its a fire risk as well as a pain in the ass!

Agreed, dead short somewhere, get it to a garage ASAP and make sure its all disconnected if your not with it, also may be worth thinking about your fire precautions i.e. extinguisher

Have checked live and negative cables along their entirity, No chaffing apparent. but I agree its something that looks like its shorting out the battery very quicklyand its something which is connected by a live wire as this occurs when the ignition is off.Have had a recent starter motor but fault was present before this was fitted but did not occur so often as it does now. Could it be something on or in the alternator configuration ???

I recently had a similar discharge problem on my 03 Defender TD5 though it would discharge overnight as opposed to an hour or so.

Spent ages trying to find the cause and in the end it turned out to be a tiny amount of oil which had worked its way along the wiring harness from the engine and into the red plug on the ECU. The amount of oil really was small and you had to take the red plug out of the ECU and remove the white insert from the plug to stand any chance of finding the oil. Just try removing the Red plug from the ECU and see if the battery drain stops, if it does it may be the same problem.

What services work with ignition off? Lights, but through a separate switch, also would blow fuse if short before the switch. Radio, possibly depending on who installed it. It must be some short if it heats up the battery terminal. The alarm system needs to be permanently connected to battery, but again, any short would need to be before fuse box.
So I would first check all cables feeding power to the fuse boxes.