Alternator goosed?

[Miked5]

After changing the gearbox and cam belt over the winter I went to go for the first drive yesterday and the low battery light/stop light came. I’ve had the car started on and off over the last month but very for a long period of time.

Things I’ve checked so far:

Battery voltage 12.2v with engine idling
Continuity between alternator live and battery positive
No blown power supply fuses (the ones surrounding the battery)

I think this points to a failed alternator or voltage regulator? Or is there anything else I should be checking before looking for a 2nd hand alternator?

In the back of my mind I’m thinking have I disturbed something on the alternator while doing the cam belts or box change but can’t find anything. If I was missing an earth surely I would see other issues aswell? Everything appeared fine before I tucked it up in the garage over winter.

 

[Miked5]

For anyone in future who has a similar issue, check your earth cables. My gearbox to battery earth cable was dodgy Replaced it with a new earth cable from Halfords and all good 14.3v at the battery now

 

[Eze264]

@Miked5 i could here my car was becoming more difficult to start so i checked the charge, 12v so i thought oh crap alternator, battery died so i put one on and now i have a charge rate of 14.60v but its flicking around to be honest like 14.60 to 13.90. What was yours charging at with a poor earth?

 

[Miked5]

When I had a bad earth mine was only 12.3-12.6v with the engine running. After I fixed the earth it was 14.3v +/- 0.1v

 

[chris_blue]

Engine turning over, wont start
Always been told start with the battery. So charged it overnight
Maxed out at holding 13.2 volts. (Should it max out at 14.4 volts as if so, battery needs replacing?)

Put back in, started fine
With engine idling, voltage was 14.4


Soooooooooo......... Is 13.2 enough to start continually? Or does battery need replacing does anyone know
Will monitor it obviously- just dont fancy getting stuck 50 miles from home and wont start

Least alternator appears working

 

[Miked5]

When the engine was turning over but not starting did it seem to be turning over any slower than normal?

The voltage should only be above 14v with the engine running and it should start will 13v however batteries can show correct voltage but if damaged they don’t have the amps/load to start a car.

A fully charged battery is normally 12.6-12.8v.

Might be worth investing in a jump starter, I’ve got a NOCO GB40 one that will start the engine of the battery is flat.

 

[chris_blue]

Yes. Turning over fine but getting nowhere after several attempts
Checked my paperwork and cant see a new battery fitted in last 6 years

So, as Ive done in past (And never regretted) bought a new Youasa battery and will fit it tomorrow

Think will keep the charged up old one in the boot for couple weeks, as supplementary power if need (I have charge leads)

Just will never trust the old battery again ......