[ROVERNET - UK] Electrical mystery continued

[Paul Smith]

1.  The battery voltage started at 12.2
2.  I ran the engine, voltage was 13.3, 5 amps going in to battery.  That
seems normal.
3.  After the run, the voltage was 12.1!
4.  When I disconnected the battery the alternator output rose to 14.8,
which seems correct.

I have left it sitting with the battery disconnected to see what happens.

Meanwhile I refitted the RH lower ball joint, but could not get it in far
enough to get the snap ring back in.  Any ideas?

PVS