I have an 1800 zetec ford focus mk2 2008 plate.

After my son went through a dep puddle recently in the focus, which fried the alternator and the battery, I had the alternator rebuilt and bought a new battery.

However, since the incident and resulting alternator/battery fix, the car intermittently loses all electrical power, that is all lights go off internally and externally, no fan etc, engine dies too. there is no warning other than that the power starts failing. When it happens I notice because the radio goes off first before power steering, lighting etc.

The power comes back on after a while, but sometimes I have had to jump it to life then it is fine. It is completely random too, It has happened more at night, but it has happened through the day too.

Could it be a bad earth after water ingress from the puddle incident? If so, where would the earth points be so I could check for corrosion?

Or could it be something else?

Hi,

This sounds like a bad alternator. Unfortunately I haven't had good experience with 'rebuilds' myself and have seen other forum members have issues with them recently as well. I would recommend getting an auto-electrician to test the alternator again before chasing alternative faults.

The main earth point is from the back of the gearbox to the chassis. That one does fray over time and could be weak now. The other one is from battery to chassis, but that's easily visible from above. There are a few smaller ones for PCM etc on the chassis rail but I can't see this type of fault being caused by a small earth point. It would also be possible for the main positive cable to be overheating over longer use if there is a poor connection to the alternator or battery.