550F charge issue?

[Davelu88]

Many thanks for all the helpful suggestions,  the problem has been solved with much checking of wires I noticed the the the wires that come from the bottom of the stator the white one had come loose but being underneath I couldn't see it , a quick push back together and she is charging up to nearly 14v from a fully charged battery 😀

[Sesman]

Superb…

[McCabe-Thiele (Ted)]

Always nice when you find an electrical gremlin and sort it - well done.

[Oddjob]

Seem to be a few of them failing on loose wires from the stator just lately. Maybe they are just getting to that age.

[Laverdaroo]

Well done, result!

[mickwinf]

Glad you sorted it out Dave, an easy fix.

[K2-K6]

Nice to get easy fix, and always good to really find out the true problem too.

I've had very few alternator confirm as failed over many years, they often get blamed but when changed the problem persists and ultimately found to be something else.

More recently had a car one go "clunk, thunk, clonketty, bonk" then charge light came on. Pulled over to inspect and found the drive pulley missing, just the alternator nose shaft sticking out with belt still going round it !
Got home to find that pulley wedged up under the radiator top hose, think that was the bonk of final resting place 
Closer examination showed that the one way sprag bearing in the centre of it had seized then the vibration resulting from that had taken it apart.
It's an overun pulley so that at low diesel engine speeds that can decelarate in abrupt phase doesn't need to be shocked through the alternator (the spindle and rotor can overrun belt speed to avoid the phase change) that also makes them quieter. It was getting a bit noisier at tickover before this, but no direct idea where that was coming from.
Two mates have similar engine that we share knowledge on, both checked to find the same seized sprag, and so preventative swap was done.
You do need special tool though  as many of these things do nowadays. 

[Bristolbadger]

Read this with interest but I've a problem with overcharging. If it ain't one thing...
Anyway, fully charged new batt and getting 19v at idle. 🫣 Using an M&P parts solid state reg/rec. Was blowing headlight bulbs, led's etc so out with the multimeter...
Yet to check all the connections especially a solid earth. But suspect the reg/rec at this stage as have heard similar issues from others on various threads... what else should I be focusing on at this stage?

Tapping into all your combined wisdom, what procedure of tests would you start with. Will get some pics up of the wiring but I must say I used the original bullet connectors from the alternator into the new reg/rec and trusted all was good after initial tests, from memory the yellows all tested very similar Ohms

Not great with elecs but have the basic skills and understanding, was wondering when I'd have a leccy problem to solve with this mongrel, she's taught me a ton already and still learning... constantly

[Bristolbadger]

Read this with interest but I've a problem with overcharging. If it ain't one thing...
Anyway, fully charged new batt and getting 19v at idle. 🫣 Using an M&P parts solid state reg/rec. Was blowing headlight bulbs, led's etc so out with the multimeter...
Yet to check all the connections especially a solid earth. But suspect the reg/rec at this stage as have heard similar issues from others on various threads... what else should I be focusing on at this stage?

Tapping into all your combined wisdom, what procedure of tests would you start with. Will get some pics up of the wiring but I must say I used the original bullet connectors from the alternator into the new reg/rec and trusted all was good after initial tests, from memory the yellows all tested very similar Ohms

Not great with elecs but have the basic skills and understanding, was wondering when I'd have a leccy problem to solve with this mongrel, she's taught me a ton already and still learning... constantly

Oops should add I'm taking 750 but guess it's all vaguely similar?

[Bryanj]

Only 2 things cause overcharge
1 duff regulator

2 volt sense wire at reg showing less than battery voltage

[Sesman]

If you have a solid state reg/rec then the culprit is the regulating part of that unit, which is overexciting the alternator field coil. If the regulator field coil connections are open circuit you will have no change in rectifier output voltage.

So in short, as BryanJ has suggested…

[Bristolbadger]

Only 2 things cause overcharge
1 duff regulator

2 volt sense wire at reg showing less than battery voltage

Ok that makes sense thanks Bryan. So if I'm to replace the unit which should I go for,

DS https://www.davidsilverspares.co.uk/CB750K3-FOUR-1973-USA/part_220371/

Or Electrex
https://www.electrexworld.co.uk/acatalog/RR24_-_Regulator_Rectifier_CB750F1_CB750K1-K7_CB750KZ.html#SID=439

[McCabe-Thiele (Ted)]

Plenty of warnings on the Electrex site about what battery types are suitable e.g. Not Lithium-Ion & downloadable fitting instructions.
Plus the Harness repair adapter if needed.

I like the original adjustable regulator on my 400.

[Oddjob]

Electrex are Mosfet type Reg/Recs IIR, always preferable.

[SteveD CB500K0]

Mosfets were cutting edge technology when I was a design engineer (early 80’s)

Surely there’s something better nowadays?


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