Alternator testing

[Paulprior]

My battery charge light stays on at start up and measuring from the cigar lighter shows about 12.5v when I disconnect the trickle charger, I know I need to check on the alternator output but it’s not so easy to remove the cover, I believe I read that there is an access hole I can use to measure when everything is in situ, is that correct and if so where is the access, one of the 3 in the photo maybe on the side facing the passenger?

[phillpot]

Put your voltmeter across the battery, should rise once engine revs pick up a bit.

[kris450]

I literally did this yesterday to help track down an issue !!

A small screw driver will pry the top of the cover off ( as per your pic, pry towards the rear of the car) just enough for you to be able to sneak a multimeter test probe in and onto the main alternator post. If thats what you're looking to test of course !!

[Sir Paolo]

phillpot said:

Put your voltmeter across the battery, should rise once engine revs pick up a bit.

Absolutely agree, it’s the easiest way.

You should see around 14v with the engine running with a healthy alternator.

[Zener]

When you find the alt bigger 8mm terminal/post also put a small load on it to check it's integrity to Batt + i.e 12v use bulb in parallel to load it not just multimeter obviously, if volts drops right off or no voltage at all check main fuse to kick off , engine running not required for this above check

Edited by Zener on Monday 19th September 11:28

[Paulprior]

Ok, so I prized open the cover, the big connector is at the top and accessible through the larger hole at the top side of the cover if anyone else is doing the same, connected a lamp from there to earth, all ok, started the engine, the charge light went out straight away and I have a solid 14.2v at tickover, so all good apart from why the change from last time?, I will try a few more times and just take it for some close to home drives to check it, but it certainly has a question mark mow, I have previously replaced the infamous 100A fuse with a midi one to avoid the cracking issue

[Zener]

Now check volts @ the batt terminals making sure you have charging numbers

[Paulprior]

I checked at the alternator as well as reading from gadget in the cigar lighter that shows voltage and has a USB port , both within 0.1V running or stopped