No combination allows the Ctek 5 to charge via the trailer socket. I've seen this model of charger just shut down on a very flat battery when the regular 'non-smart' charger will just charge it. So it could be oxidised connectors/old wiring or the Ctek not liking the load it's detecting. I'm going to find an old style charger and try that before giving up on charging through the trailer socket. Car may be on the drive for a while! Key won't open the lock manually. Wondering if I inadvertently 'superlocked' the car somehow on Thursday when I was messing with the weak signal on the fob?

The buttons on the key always activate superlocking Martin. RAVE says that in this mode, using the key blade in the lock barrel will still unlock the door.

Has any work been done involving removing the driver's door card?

Simon

The intelligent chargers will not charge a totally flat battery, I have got around this before by bridging to pos and neg poles with a pp3 9v battery with the charger attached, this fools the charger into thinking it is almost flat and it begins charging ;).
Or, if you have a 2nd charged car battery, you could try to fabricate a pos and neg lead from the 2nd battery to plug into the towing socket.

I've never had the door card off, but I'm sure it has been off at some point in the past. Rick said the manual key worked OK when he had the car and the battery went flat on him when stored, but I've had the car over a year now, which is plenty of time for something to shake loose behind the card I guess. I don't recollect trying the key to unlock until this weekend.

That confirms my suspicions. I've got an old style Clarke machine, but it goes to high amps on a flat battery and I don't want to risk blowing any fuses in the trailer electrics. I'm guessing a safe current would be 15a or less. If I go low and use a trickle charger, or even fool the CTek into charging, it might not be enough to overcome whatever drained it that was causing all the clicking. I think I need to aim to charge at around 10a to ensure the battery charges despite the drain but also avoid blowing the fuse?

If the key worked manually before and no work has been done to the door it will be the cable that has snapped that connects the key assy to the lock assy. door open door card off and strip down reqd

It does feel like there is nothing there, so a snapped cable would explain that. Just have to get into the car to get started on the door card. Hopefully one of the other locks will open when the battery is re-charged. I've ordered a 10a current limited variable DC supply arriving tomorrow. It was the same price as a 10 amp battery charger from Halfords but more versatile. Hopefully it won't fry the fuse in the tow socket line but will overcome the current drain and charge the battery. I can't push the car so I'll have to make up a 20 metre test lead to the socket so the power supply will be under cover.

Thanks Jon for that.
I have a thirteen pin socket which I assume is a Euro socket. Pin 9 should be live and pin 13 ground. I was worried the current from another battery might exceed the fuse rating on the circuit if the battery in the car is very flat. It will be great if it works. I guess I could put a 10a in - line fuse as a precaution. I shall give it a try tomorrow and report back:}

Why should you not use a charger ?