Hi,
I have a Hymer motorhome on a 2004 2.8 JTD Chassis.
On trying to start it a few weeks ago I found the battery to be completely flat.
I tried jump starting it but my jump leads aren't up to it so I called the AA, they diagnosed a duff battery and duly sold me a new one. We drove about 800 miles on the new battery without a problem until the weekend, when I tried starting it after it had been sitting for 4 weeks, and the battery was completely flat again.

Having charged the battery fully over night and re-fitted it I have a number of additional problems :-

1. The main engine cooling fan comes on as soon as I connect the battery. The ignition is off and the engine is cold.

2. When I turn the ignition key no warning lights appear, the immobiliser doesn't function but the engine turns over.

3. No other electrical components work.

4. The 7.5 amp fuse to the ABS system and the 125 amp alternator fuse, on top of the battery, have blown. All the remaining fuses are fine.

I think the alternator fuse having blown would stop the warning lights showing and I've read on here that a faulty alternator can drain a battery but would it also blow the alternator fuse?
Also, what would cause the ABS fuse to blow in these circumstances? Is it just a by product of an alternator problem?
Should I just replace the fuses and cross my fingers, hoping they don't blow again!

Any help will be greatly appreciated,
Thanks