51 Plate GTi issues

[Glowstone]

A lead acid battery can drop down to about 6 or 7V under a very heavy short term load (starter motor) but it will not drop below about 12.1V under a draining type load if it is healthy. The current will cease before the volts give up. Leaving the lights on falls in to this category.

Under a very light current the voltage can drop to the point that the sulphur in the acid deposits itself on to the lead plates. Once that happens the battery is done. Car alarms draw the right amount of current to kill even a brand new battery given enough time. Normally a voltage reading of 11V or so means that the plates have sulphated. It does take a long time though.

I haven't seen a battery give up 2V. 9v or so when a cell (or two) was dead and 10.8V when the alarm had killed the battery are the lowest I have seen.

Quality...thanks for those nuggets 

I had an assesment graph scrawled down with all the battery figures on to know what to test for (expected volts/ amps generally for a battery) but it went west..probably rolled up in a fag and smoked?

I just asked my friend by text if she can verify  the battery was properly new or used...her boyfriend told me it was new....I want to find out !

[Mr_Orange]

Puddle lights could be as simple as a bulb out, but my money is on microswitches in the door lock modules. Again, another typical and fairly painful repair.
Ref the coolant leak, check the coolant flange on the side of the engine (with temp sender in), these can leak ;-)