Went to start my defender and found the battery was pretty flat.
Turned the key to turn the ignition on, glow plug light came on and went out 4 or 5 seconds later as normal.
Without turning the key any further, about 5 seconds later there was a real groaning noise from the passenger side, it sounded like it was right in the bulkhead, at the same time the voltage came up by a couple of volts, although still low.
Not sure whether this was the cause or because of a flat battery
Any ideas, never heard anything like it before.
