On Sat, 25 Feb 2012 10:13:27 +0000, Martin Brown wrote:

I suppose it is possible that the charger is too clever by half and sees
even a small resistive load in the cable as nearly charged battery.

I thought the "extension cable" was between the mains supply and the
car which contained the charger. Thus thuis being the US and 110v the
volt drop on the cable when (trying to) pull a decent current was to
great perhaps causing the charger to drop out due to low supply
volts.

--
Cheers
Dave.