Battery light was on with engine running, headlights on, so I put the multimeter across the battery and was reading 9.8v ,. I tried to wiggle the alternator connectors to see if that made any difference, none. I decided to put the heated rear on, then it jumped to 12.8v and the battery light went off.
Recently sometimes the battery light has been coming on, sometimes it will go off. No consistent pattern. Sometimes instead of the battery light getting brighter when u switch on more load ,it gets a weaker red (the load goes up so the alternator must suddenly kick out more power). Somehow its like if you switch the heated read on and off it kind of wakes up the alternator. Would this indicate a specific part of the alternator failing?
An AA mechanic suggested igiving the alternator a whack as this sometimes 'cures' it?
How do you test if the cars earths are ok?