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alternator charging oddities


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12 replies to this topic

#1 VaporTrail

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Posted 12 December 2004 - 01:30 AM

82 Brat. Dual Batteries with solenoid between them. Xt6 Alternator.

when I first start it up, it will not charge. as soon as I take it over 3500 RPM's then it will charge,even when RPM's go lower...

bad diodes, or need a new wire from alt to battery?

#2 NorthWet

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Posted 12 December 2004 - 02:03 AM

82 Brat. Dual Batteries with solenoid between them. Xt6 Alternator.

when I first start it up, it will not charge. as soon as I take it over 3500 RPM's then it will charge,even when RPM's go lower...

bad diodes, or need a new wire from alt to battery?

Funny that you should ask... my alt (non-XT6) started doing something similar a couple of days ago. I haven't dug too deep into yet, as week-long deluge here makes it inconvenient.

Anyway, first thought was worn brushes, but the voltage stays slightly too high on mine, so I am beginning to think VR. I'll swap it out and have it tested, hopefully tomorrow.

#3 ShawnW

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Posted 12 December 2004 - 10:27 AM

Id guess moisture or oil is getting in the brushes and that spinning the alt at that RPM is giving them a quick cleaning so they start working.

#4 Vanislru

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Posted 12 December 2004 - 11:49 AM

Get a can of Contact cleaner, electrical wholesaler should be the cheapest, and give the alt a solid blasting around the brushes. Should remove any of the carbon and crap.

#5 Cougar

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Posted 12 December 2004 - 01:31 PM

I very much doubt that the diodes are causing this but it could be the brushes as was mentioned or also the regulator, rotor, or stator. I would suspect the regulator the most. At any rate, it seems you are going to need another alternator unless you pin it down. If you have more than 80k miles on the unit then I would replace it with a remanufactured unit.

#6 NorthWet

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Posted 12 December 2004 - 02:42 PM

Almost a hijack:

Anybody have any luck disassembling the GL-series alternators? I think that I tried once, and have a few partially torn-down ones that others have tried and failed on.

I used to replace brushes all the time on other styles (Datsun, Mistu, GM), so would be nice to try that on soobs. ("all the time", 'cuz I have around 500k miles of road behind me...)

End of almost hijack.

#7 naru

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Posted 12 December 2004 - 03:51 PM

Almost a hijack:

Anybody have any luck disassembling the GL-series alternators? I think that I tried once, and have a few partially torn-down ones that others have tried and failed on.

I used to replace brushes all the time on other styles (Datsun, Mistu, GM), so would be nice to try that on soobs. ("all the time", 'cuz I have around 500k miles of road behind me...)

End of almost hijack.



Yes,Brushes are a piece of cake.Requires a soldering iron.
Regulator a little trickier,but not much.

#8 NorthWet

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Posted 12 December 2004 - 05:04 PM

Yes,Brushes are a piece of cake.Requires a soldering iron.
Regulator a little trickier,but not much.

OK, not an issue with soldering, as I have ElecTech experience. But my problem is separating the unit to get at them. On all other alts that I have worked on, the back case came loose from the stator/rotor/front housing pretty easily. IIRC, the one time I tried that with the soob it frustrated me.

Any hints? Or is my memory flakey?

#9 naru

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Posted 12 December 2004 - 05:24 PM

OK, not an issue with soldering, as I have ElecTech experience. But my problem is separating the unit to get at them. On all other alts that I have worked on, the back case came loose from the stator/rotor/front housing pretty easily. IIRC, the one time I tried that with the soob it frustrated me.

Any hints? Or is my memory flakey?


Been a while since I did it so I had a quick look at the FSM to be sure.
Just remove the through bolts and tap it apart.EA-81,but I`m sure they are all the same.

#10 torxxx

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Posted 13 December 2004 - 12:15 AM

EA81 and EA82 alts are the same after a certain year. I think its 1984 and newer have the internal voltage regulator. I used a alt from a 85 brat (on my 86 ea82) and it works great.

Taking them apart is easy. just take out the 4 phillips head screws on the outside and tap the mounting ears apart.
When you are putting it back together, you have to push a piece of bailing wire through the back of the VR half of the alt. it holds the contacts in that push onto the brushes.

I've rebuilt about 10 of them. only two didnt work, and that was because I had two different size alternators.

#11 subaru_styles

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Posted 13 December 2004 - 01:32 AM

hey Mcbrat,

when I bought my coupe it was doing the exact same thing.....1 week later the alternator took a crap on me.

#12 NorthWet

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Posted 13 December 2004 - 01:43 AM

Changed out my alternator today. As expected, the voltage came up as it should without revving. Plus, the voltage stayed where it should, about 1.5 volts lower than where it has been recently.

McBrat, good luck. Definitely change out that alt before it leaves you in a world of hurt.

#13 All_talk

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Posted 13 December 2004 - 02:32 PM

82 Brat. Dual Batteries with solenoid between them. Xt6 Alternator.

when I first start it up, it will not charge. as soon as I take it over 3500 RPM's then it will charge,even when RPM's go lower...

bad diodes, or need a new wire from alt to battery?


Sounds like its not self-exciting, might be a problem with your dual battery system, did it work normaly with this system before? I had the same problem with a dual battery system in my '65 Pontiac, Just gave her a rev and lived with it for years.

NorthWet, I've got a Subie alternator apart on the bench, you can stop and take a look next time your in E-burg if ya like. And while you're here you can check out my new shop toy... Its got lots of levers and cranks and turns bigger bits of metal into littler ones. :D

Gary




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