alternator break in? (1 Viewer)

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danthman114

danthman114

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I read through an older thread on a guys volt gauge pulsing and one comment on there said a new alternator will do that and fluctuate voltage. he said that you need to run it for a good 10 hours so the brushes wear enough to form to the armature. it makes sense but is there any truth to this?

not too long ago my voltage regulator went out and I bought a Toyota reman and now I'm getting weird goings on...
first off, I have the blue seas auto charge relay and switch to go with it. theres an led wired into it to show if its isolated on start, low voltage lockout (9.5vdc), or charging. i also used #2 welding cable for the entire system accept the start cable is oem.
now when I'm sitting at a light and have the ac on, and my lcp fan on i can see my voltage drop and the batteries isolate because of discharge.
could it be that the new alternator brushes need to seat properly?
 
No expert here, but I've not heard or experienced this.
 
Brushes are typically already 'beveled' to sit on the commutator mostly ok. Obviously they fully seat and conform to the arc of the commutator as they wear in.

I've not seen voltage issues due to new brushes.

Certainly AC clutch engaged and a big electric fan are going to be pulling decent amps (20A+ likely), so at idle a typical alternator will be challenged to maintain a high charging voltage. What's the health of your battery like? Rev up the engine a bit (vs idle) and see what RPM the engine needs to be at for the batteries to combine again. I'd assume by 1000rpm all should be happy.

cheers,
george.
 
george_tlc said:
Brushes are typically already 'beveled' to sit on the commutator mostly ok. Obviously they fully seat and conform to the arc of the commutator as they wear in.

I've not seen voltage issues due to new brushes.

Certainly AC clutch engaged and a big electric fan are going to be pulling decent amps (20A+ likely), so at idle a typical alternator will be challenged to maintain a high charging voltage. What's the health of your battery like? Rev up the engine a bit (vs idle) and see what RPM the engine needs to be at for the batteries to combine again. I'd assume by 1000rpm all should be happy.

cheers,
george.
Click to expand...
It could be my optima got cooked a bit when my regulator quit. I considered that. At 700 rpm without fan the voltage will dip to 12.8 with ac on. With rpms at driving the voltage will go up to 14.1ish and the 13 range sometimes. If I have to replace it I'm going to go the Sequoia alt route. Hopefully I can get a bracket from photoman
 
^ Just AC running and 12.8V at 700rpm seems way too low for a good alternator and good battery (assuming wiring etc are all good).

12.8V is nominal for a fully charge battery voltage with no load. So, seems like your alternator isn't doing a good job.

You should be measuring voltage across the battery with a 'reasonable' meter to get a true idea of alternator/battery voltage.


cheers,
george.
 
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So what I think I'm going to do is rebuild the old alternator and try it out. If it still does it I have other problems. But only after checking all my ground points. If I ever have to use my winch I'll worry the whole time. OCD induced worry sucks!
Today after work I'm going to disconnect my whole dual battery circuit and run it to see. Then test the cells of the main battery.
 
Unfortunately I have yet to see a reman unit match OE in performance and longevity, no doubt there good workshops out there but are few and far between. Plenty of poor quality chinese components out there makes the situation worse.

I have not read the complete thread but some points to look into.

Both batteries should be of the same age, type and power, this allows comparison of charge condition.

Make sure both batteries are earthed not only to the body but to each other as well.

Make sure engine block is well earthed.

Check the plug in the rear of the alternator, this can give weird dashboard readings.

Test batteries when disconnected from each other, one bad will pull the other down.

Regards

Dave
 
Last edited:
Dave 2000 said:
Unfortunately I have yet to see a reman unit match OE in performance and longevity, no doubt there good workshops out there but are few and far between. Plenty of poor quality chinese components out there makes the situation worse.

I have not read the complete thread but some points to look into.

Both batteries should be of the same age, type and power, this allows comparison of charge condition.

Make sure both batteries are earthed not only to the body but to each other as well.

Make sure engine block is well earthed.

Check the plug in the rear of the alternator, this can give weird dashboard readings.

Test batteries when disconnected from each other, one bad will pull the other down.

Regards

Dave
Click to expand...
I'm going to get on camelback and get the parts needed and do it myself and keep the "new" one in a glass case for emergency if I don't get the sequoia one instead. the way I have my batteries set up is the only time theyre combined is during charge or if I manually combine them. they isolate on discharge or overcharging. I checked the 2 battery grounds yesterday and theyre good. I used 10 ga crimped and soldered. ill look into the plug on the back. when I installed it I put alittle dielectric grease on it beforehand.
 
well today, this morning, I started it up and listened through the grill and I can hear the alternator. I do believe a bearing is going out. it has a grumble that wasn't there with the old alternator. wonderful, just wonderful...
I guess I'm going to order the parts needed to fix the old one and throw it back in which leads me to my next question. the website totoyota.com, are those oem because they seem to be cheaper than the camelback website. they list the Toyota part numbers...
 
In my area, we still have some good shops that will rebuild alternators. I would do that before before buying a rebuild of unknown origin. JMHO.
 
I'll change out brushes and maybe bearings, but I've never rewound a stator. Not sure something I want to tackle for the few times I need it done.
 
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