Alternator playing up. (85amp Falcon alternator on 18RG)

[JadeEstevez]

Okay so about two weeks ago my Alternator died, It was an 85amp EA Falcon alternator from U-pull-it so it was a ticking time bomb anyways... I went out and bought a brand new 85amp from Sprints instead of rebuilding the old one (I'm lazy) and bolted it in, Everything was working great, It was charging at 14volts just like the old one did... until recently that is. When I first start the car it charges at 11volts and stays there until I reach 5000RPM, Then it starts charging at 14volts like normal. The wierd thing is, After it begins charging again there is a dead zone where it won't charge properly.
I'll try explain it like this:

...Idle - 2000RPM: Full charge, 14volts
2000RPM - 2500RPM: 11volts
2500RPM - 7000RPM: Full charge, 14volts

Now does anyone have any idea what the hell is happening? O___o It's frustrating me, It wasn't doing it before and the old one didn't have this issue either.

Thank you.

[stealth]

Does it have a voltage regulator hanging off the back? Sounds like the reg is pooped. Brushes may be replacable...

[JadeEstevez]

See, I thought that too but the alternator is brand new... Unless I got a dud one, That seems to happen a lot when I order new parts. Something wierd happened again, It's now functioning like normal?? What the hell could have happened? O_O

[Javal]

If you got it from sprints it's probably the cheap chinese repro that everyone is selling.

[JadeEstevez]

It's a bosch alternator though? Has bosch started making the shit in china now?

[Javal]

It's a bosch alternator though? Has bosch started making the shit in china now?

If it's stamped bosch then I doubt it. I know one of the main auto electrical wholesalers in Adelaide don't supply bosch EA falcon alternators anymore and are selling chinese made ones (which, by all accounts, aren't actually that bad) at a lesser price. I drew a few assumptions and would not be surprised if sprints use this wholesaler.

Anyway, if you bought it brand new, get it tested, get it replaced under warranty.

[JadeEstevez]

Yeah but to get it replaced under warranty I have to remove it and it's my daily >___> It's working fine now, Which is odd.

If it starts happening again I'll pull it out and get it replaced.

[ta22fan]

Maybe just the new brushes bedding in? Not something I would expect to see on a quality unit tho....

[oldcorollas]

one thing I have had happen to at last 5 Bosch alts so far, is that the soldering of the main wires inside gets brittle with age and breaks... so it only charges on 2 out of 3 coils or something.

I can7t remember exact details, but I think it was where the main stator coil wires connect to the field diodes?
just get big soldering iron, and resolder the joints, and should work again.


in this pic, the white wires... the solder breaks between them and where they go on the diode panel thingy

this is also for the older style alt, not the modern compact type, but might be same cause?

you can diagnose it with an LED battery voltage kit (jaycar/DSE) with 10 LEDs, cos the voltage is not steady, and since the leds have fast reaction time, you can see the voltage going up and down at a fast rate (if one coils is not charging, then it's missing voltage 1/3rd of the time)
edit2: I killed a few with vibration, but some also died in their natural habitat, ie in falcoons..

[JadeEstevez]

It was a new alternator though, Would the solder really be that crappy fresh from the box?

[oldcorollas]

oh, should be ok if brand new.

was the alt painted with silver paint?
another thing that can prevent charging is shitty electrical connection to the motor via the brackets, or crappy earth lead from motor to chassis/battery.
probably not the case here, but I've had that happen before...


oh.. you've never had something fail when new?

[JadeEstevez]

oh.. you've never had something fail when new?

It happens way to often, If it isn't broken from new then it's the completely incorrect part... I always just thought it was bad luck.