Alternator schmalternator

[4lex]

96 HDJ80. I recently 'upgraded' the alternator as I have started towing an RV which has an absorption fridge, elec brakes and a 30a dcdc onboard. I run a 60a dcdc in the 80. Might have been ok on the stock unit but I went with one from a reasonably reputable supplier here in oz that puts out 180a, and it did a good job for a couple of thousand.
Today, when I'm 600 miles from home and 200 from any realistic spares options, the cinch bolt on the tensioner bracket s*** itself. I heard it go, and hoped it was just a stone flicked up, but momemts later the dash is lit up, and I pulled over to see the belts slack and could feel the sheared off bolt.
As a quick fix I pulled a lashing strap round the alt to the chassis and drove a small softwood wedge in between the block and the alternator which gave me enough tension in the belts to keep them on for 6hrs of driving at 2500 rpm.
Thing is, although my 'fix' made the dash lights go off, there's no charging. 3hrs into the drive I hear the battery monitor in my rear build losing its s*** and find the pair of lead acid batteries I have in the front are down to 12.2v, as they've been running all that other stuff and getting no charge.
I pulled out my solar panels and hooked them up for an hour while we had some food in the rv which would give me about 30ah and the batteries lead acid batteries went up to 12.5 and started the truck. Disconnected the various loads aside from the trailer brakes and we made the 5hr drive to a place I can buy parts. I was glad I had an old mechanical diesel that doesn't require any electrical input to work, and rued the day I ordered a 300 to replace it.
I don't buy that the alt tensioner failed coincidentally with the alt. Welcome thoughts on what might have happened here. I'll be able to pull the faulty unit tomorrow.
Cheers,
Alex

 

[4lex]

Some progress. I pulled the alt this morning and noted that the pivot bolt housing on this so-called uprated unit isn't close to the right size for the OEM bolt, thus allowing it to rattle around on the mount, eventually fatiguing the cinch bolt to failure. Quite how this physical failure coincided with electrical failure however remains unclear.

 

[4lex]

Does anyone know how to bench test the alternator? I can spin it up with a drill, what should I see on the pins? And what should I see on the 3pin connector on the vehicle with no alternator connected? Cheers

 

[doc_random]

Does anyone know how to bench test the alternator? I can spin it up with a drill, what should I see on the pins? And what should I see on the 3pin connector on the vehicle with no alternator connected? Cheers

Some auto parts stores have alternator testers. Mount the alternator on a post, attached the wires and belt. Pull the lever in the center this picture to tighten the belt. An electric motor spins the alternator while the display shows results. Seems safer than try to use a drill.

 

[TrickyT]

Find a place that rebuilds alternators and see if they have a test stand that can test your alternator. This is a MUCH better approach than "spinning it up with a drill" since they measure the output of your alternator under load. If your HDJ80R uses the same alternator as an FZJ80, then full output is 80A.

As far as the 3-pin connector goes, pin 3 (black wire) supplies the current for the rotor, pin 1 (yellow-blue) powers the red "not charging" lamp in the dash (0v means lamp lights, 12v means lamp is dark), and pin 2 (black-blue) enables the voltage regulator when the ignition is on.