What kills alternators?

I keep killing them....

last one was a "brand new" aftermarket unit....died after like one rally...Was SUPER hot when i took it off.

Amperage demands are not huge....

2 x 35 Watt HID driving lamps = 5.8 amps
2 x 55 watt Driving Lamps = 9.16 amps
2 x 55/65 watt OEM headlights = 10.83 amps

total lighing amps = ~25 amps.

should be more than managable by the stock 75? amp alternator.

Battery is a Deka/Braile "race" 15lb race battery, located behind the co-drivers seat. Heavy 1 AWG welding cable runs from there, through battery switch, to the post on the starter. A heavy 4 AWG cable runs from there to the OEM location on the OEM fuse panel.

Very confused....and getting expensive....

Have not bothered to get someone to check the dead alternator to see what is up with it...

Ideas? Sugggestions?

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Chris

I had problems too but switched to an STi 90 amp alternator and so far so good. And I'm drawing more amps then you with 6 auxillary lamps and headlights.

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Gone fishing

I used to run a 2002 wrx. 3 years, 16 rallys. Never had a problem with the alternator. Carried a spare in the van. Never touched it.

I have heard more than once from pro mechanic types that a lot of "rebuilt" ones are shit, though, but no one could explain why. Maybe 'cause that's what someone told them. So I buy used un-rebuilt ones for spares.

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Ted Mendham
www.rensport.net

could it be the battery? I've heard not so good things about the lightweight 'race'batteries not holding a charge. Add the fact you've got it going through ~10feet of wire....maybe?

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Jon Burke - KI6LSW
Blog: http://psgrallywrx.blogspot.com/

It's possible the battery is causing the problem...but doubt full.

It holds are charge just fine, it will die if you leave in unattended for months...but i have been very impressed with the battery, especially for it's size.

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Chris

Chris,

Hmmmm..... are you using an OEM alternator for the EJ20?

Otherwise (if it's from the EA engine) could increased RPM be an issue?

Rich Smith

Used OEM alternators for the 91 Legacy Turbo Fitment....roasted a couple....

Used alternators for the 1998 2.5rs fitment...this was the latest victim.

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Chris

Just a couple of ideas:

Check alternator speed. Are your pulleys stock size?

Check air flow to the alternator.

Check maximum current flow from the alternator with a clamp on meter.

Good luck, Robert.

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Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

tedm Wrote:
-------------------------------------------------------
> I used to run a 2002 wrx. 3 years, 16 rallys.
> Never had a problem with the alternator. Carried
> a spare in the van. Never touched it.
>
> I have heard more than once from pro mechanic
> types that a lot of "rebuilt" ones are shit,
> though, but no one could explain why. Maybe
> 'cause that's what someone told them. So I buy
> used un-rebuilt ones for spares.
>
>
>
> Ted Mendham
> www.rensport.net


I have a mechanic friend who couldn't get a break from changing newly dead newly rebuilt alternators out of his personal car. FWIW

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Andrew M
Onterrible
30ish

Rallymech Wrote:
-------------------------------------------------------
> Just a couple of ideas:
>
> Check alternator speed. Are your pulleys stock
> size?
>
> Check air flow to the alternator.
>
> Check maximum current flow from the alternator
> with a clamp on meter.
>
> Good luck, Robert.

I'm no expert, but my simple understanding is that the Alternator doesn't "see" the load it's running.

It's producing electricity regardless.

I could be completely wrong here.

I would imagine the roasting has to do with poor quality, improper cooling/getting too hot, maybe even too much tension on the belt roasting a bearing.

Your dead alternators are not making power anymore, but the shaft spins fine? What?

Cheers,

Andrew

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Andrew M
Onterrible
30ish

Nippondenso has a pretty good line of new replacement alternators. Many of the remans are not so good. I see about 20% failure across the board. Suncoast, Delco, Motorcraft, Endurance doesn't seem to matter. We just got 3 bad alternators in a row for a diesel Ford. I suspect they all had the same shitty regulators from a bad batch. Switched brands no more issues.

Change the pulley size to slow the rpms. Most street cars never see past 3k. I'd also try to get up around 100 amps.

I sell Deka batteries, lotsa failures there too. Nothing is worth a hoot anymore...

Andrew,

How could an alternator not "see" the current it is producing? The more current the alternator produces the more heat is created.

I taught basic electrical systems at the local community college.

Gene,

I agree. Probably a low quality alternator being turned too fast.

I have seen a few "lifetime warranty" alternators that had old bearings in them!

Robert.

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Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

Check alternator voltage out put at alternator and at battery with car running at higher speeds (as if running event) and see if the charging voltage is dropping off-over running alternator, also load test battery (engine off) to test for battery reserve voltage/battery life, remember the vehicle electrics run off the battery and the alternator keeps the battery filled (battery is capacitor).

If voltage is dropping check battery an alternator voltage at different engine RPM, also do voltage drop and see if there is poor connection between battery and alternator (voltage lower at battery then at alternator)-don't forget engine to frame ground and possible alternator housing to engine/frame ground wire/s...

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As always IMHO

SEAN TENNIS KF7JJR
SEATTLE, WASHINGTON
SAAB 99, SAAB 850
SAAB V4, SAAB 99T

Rallymech Wrote:
-------------------------------------------------------
> Andrew,
>
> How could an alternator not "see" the current it
> is producing? The more current the alternator
> produces the more heat is created.
>
> I taught basic electrical systems at the local
> community college.

Robert,

Please re-read my post. If I still sound like a moron, then I must be.

Cheers,

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Andrew M
Onterrible
30ish

what is in the car now is i suspect an OEM subaru alternator (mitsubishi) unit, but unknown history...likely off some JDM clip...

I suspect picking up a NEW unit will be the best bet, along with checking everything mentioned.

I am using the stock OEM pulley...well almost...i have used a fancy pants alloy replacement from a sponsor once or twice.


The latest unit that was "dead" was spinning free no problem...but noticed when pulling into a control that the battery light in my SPA gauges would flash (set to 12V). This was with just the OEM headlights on.

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Chris