Join Date: Jul 2006
Nominated 11 Times in 37 Posts
TOTW/F/M Award(s): 17
Thanked 2,467 Times in 1,851 Posts
I'd be inclined to think its a circuit which has quite a large 'draw' on current, something like the engine cooling fan, for example (rather than the stereo remaining on). Your best bet would be to get an auto electrician to test which fuses are remaining 'live' after the ignition key has been removed. I would presume that only the alarm, stereo (code), immobiliser, and central locking should be the only items which should receive power.
Another possibility (although its a bit of a long shot), is that the new battery has a defective cell - cold starts require more 'shove' than warm starts, so it would be a good starting point (pardon the pun)
Hope that helps.
This job should never be complete - the day I think I've done it all, is the day I resign.
Currently in VelSatisfied's garage:
2005 FIAT Ducato 2.8JTD LWB Gran Volume, 2000 Kawasaki ZZR 1100 D7 'fullpower' in black + full GIVI & KAPPA luggage, 2007 MB R-Class 320 CDi Sport LWB uprated by Brabus to 300Bhp don't know if there's a 155mph limiter - will be fun finding out! 2004 Mercedes Vaneo 1.7 CDi Ambiente 7-seater