Alternator issues

[cmacp5]

I have searched the forums and have not found my issue,

I have just replaced my TD42 alternator with a 100amp one, the car has been set up to bypass the original charge fuse and has been replaced with a single cable from the back of the alternator through a fuse and straight onto the battery. (not my doing)

All I did when I replaced the alternator and a thicker wire and 120amp circuit breaker. the alternator came with a plug that fit the original also.

The issue I am having is that after 5 minutes or so, I am tripping the breaker... now that could be on revs or not on revs. I cannot seem to source a short in the wiring and all earths are brand new and tight.

Getting 13v at idle and 14 above about 1200RPM

I am lost as to what is happening and hoping someone can shed some light.

Also I am running an Optima blue top AGM battery (which I don't think should matter?)

[Cuppa]

Just thinking aloud.

Voltages seem ok. I’m assuming the battery is in need of a good charge & thus accepting whatever the alternator can output & that the CB is one which will pass an over rated current for a short time before tripping. If the battery is close to fully charged I think there’s a problem

Maybe you got lucky & have an alternator which outputs more than it’s rating?
Can you substitute a higher amperage breaker to see what happens?

If it were me I’d take to an autoelectrician & get them to measure what is going on..... they might just suggest a higher rated CB??

EDIT: Another thought. 1200rpm seems quite low revs to be getting the full whack from the alternator - are you sure you have the correct pulley on the alternator? If not & it were spinning too fast at normal driving revs that could result in the problem you are seeing.

I note you are new here, can you head over to the intro section, it’s generally considered good forum manners to introduce yourself, & you’ll likely find you get a better response. Please also feedback what the story was once you get it sorted. Feedback makes those who try to help more likely to help the next person or yourself should you post again. Good luck getting it sorted.

[cmacp5]

the battery has not had a good chance to charge your right. I have got it on a charger at the moment while im at work.

Are you able to explain this a little further?

"that the CB is one which will pass an over rated current for a short time before tripping"

*sorry edit* re-read it, you think that the alt could be putting out more then 120 amps... could that explain the wire being warm and the alt heating up a decent amount after say 10 minutes...


thanks

[Cuppa]

Check my post above, I added to it. I’ll put my money on the wrong pulley.

[cmacp5]

Just thinking aloud.

EDIT: Another thought. 1200rpm seems quite low revs to be getting the full whack from the alternator - are you sure you have the correct pulley on the alternator? If not & it were spinning too fast at normal driving revs that could result in the problem you are seeing.

I note you are new here, can you head over to the intro section, it’s generally considered good forum manners to introduce yourself, & you’ll likely find you get a better response. Please also feedback what the story was once you get it sorted. Feedback makes those who try to help more likely to help the next person or yourself should you post again. Good luck getting it sorted.

Thanks for that, it could be possible, hadn't thought about that.

I will put up the intro sorry, being at work and not being able to sort out my car just wanted to see if anyone knew.

thanks again