I've read a lot of posts and they've given me some things to think about but nothing that fits my issue.

the car is a UK Ford Focus 1.6 TDCI on a 55 plate (First registered in 2005 I believe) Other than a new turbo it's stock.

The problems started a couple of weeks ago when I went to unlock the car with the fob and nothing happened. To cut a long story short the car was dead and after first getting imobiliser PAT code 12 I took the battery off for half an hour, reconnected and got a jump start and all was good for a while. After speaking to a friend of a friend who is a ford mechanic he suggested that the recent rain might have got into the fuse box under the glove compartment and caused a drain on the battery as he has fixed a few of these cars with that issue. Seemed unlikely but the car was working so I drove as usual.

Then two days ago I was driving in the rain, hoping the car would work fine which it was until we parked up and came back to the car 10 minutes later. The car unlocked fine, PAT light was flashing as usual etc.. put the key in, turned it to ignition and it immediately died. Back down to 4.7ish volts on the battery. Got a jump start and drove it home, as long as the engine wasn't turned off it was fine. As we got home and I was about to park up I heard the relays under the glove box start clicking like mad as my power steering/braking died and all the dash lights flashed on. Lasted a couple of seconds and everything came back (engine remained on the whole time).

The next morning it started fine so I hoped all was well. 50 miles later in the rain after parking up for about 5 minutes the same thing happened. got a jump start and went home, about 5 minutes of driving and I hear the relays clicking like mad, power steering goes, no lights, no radio display, nothing. Car stalls and we coast into a layby. Again the battery is ready 4.7ish volts, slightly erracitcally so I guess the battery is naff.

I figure that if there is a drain on the battery it should show a slightly higher reading when the positive lead is disconnected so I take that lead off and test the battery. 12.7 volts, perfectly full battery, that's not right.... Reconnect the positive lead and still at 12.7 volts. The battery was never dead instead it had an 8 volt drain on it somewhere which was cleared after disconnecting it for 5 seconds. Start the car and everything runs fine, alternator is putting out nearly 14 volts, all instruments and lights work so we gingerly drive home. We get home mostly without incident except for the power steering light showing for about 10 seconds (even though steering felt fine for that time) and then a random stall just after leaving a toll booth. Hazard lights were still working after the stall so the drain had rectified itself and the car started fine and we got home.

To summarise: Car develops a battery drain that "neutralises" about 8 volts during the rain. The drain only seems to occur AFTER I turn the ignition (Since remote locking still works BEFORE turning it then after turning it I loose ALL electrical systems, seems the ignition causes the drain)

Drain is *possibly* cured by disconnecting the battery for just a few seconds.

Battery *seems* fine since it starts the car reliably once the drain is "rectified"

Alternator puts out about 14 volts at idle

Any ideas? Going to try to put my multimeter on the battery and pull fuses to identify which circuit causes the drain although I will only be able to test it when the drain is "active" IE after trying to start the car and failing.

Only other issue is that the Horn stopped working several weeks ago even though the fuse is fine. Is it possible that the horn wires behind the grill are getting wet and causing an 8v drain?

I just want to see if there's anything I can do before getting it to a garage!