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Charging system help needed

prove_it

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Jul 3, 2008
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Sioux Falls, SD
So I had to head out of town a couple of days ago. I made the whole 1200 mile trip ok and never had any breakdowns. Now here's the problem. It seems that as I got 300 miles into my trip my car would die and restart in a split second, like turning the key off and on real quick. This would happen when touching the brakes, whether or not the headlights were on. I started to think that maybe the battery was headed out. Well I made it to the hotel and waited til the next day and get the starting/charging system checked out. Well the next day I had no issues at all and didn't worry about it. Fast forward to today, problem is consistent now. I had the systems checked and was told the battery was good, and the alternator has low output at about 30A. Well being 400 miles from home, and having installed a new alternator about 6 weeks ago, I just starting driving home and took the chance. She got us home safe.
Here's the facts,
My battery gauge at idle reads about 11.5-12.0 volts, and 12.5-13.0 volts off idle no loads. Also voltage at bat terminals reads the same.
With all lights off at idle or off idle then stepping on brakes the clock will dim briefly then go full brightness.
The alternator at the time was only showing about 30 amp output, loads and no loads.
I drove 1200 miles like this. I have a brand new AC Delco Alternator I installed 6 weeks ago. I also cleaned up and re-taped the wiring harness and washed everything off. I replaced the alternator since the factory one completely failed. I have yet to check the voltage at the alternator output terminal to determine that it's not the chargeback wire.
Question is, Is there anything else besides the chargeback wire that could cause a weak alternator output besides the alternator itself?
And how could I have made it so far if I only had about 30amps of charging power? I even had the headlights on for a while too.
 

broxma

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Joined
Nov 16, 2009
Messages
911
Location
San Antonio Tx
Well the honest answer is that the car really doesn't use that many amps under a constant load as you noticed. The usage is mostly intermittent so even if the alternator is only pushing about half it's rated output, you would be fine. The current will just draw from the battery in a high demand situation.

The real problem is why are you blowing through alternators. I just rewired my entire charging system the other day while looking for that cause of my CEL's. It is almost too simple a system to screw up and I am sure your capabilities are well within the scope of doing such a thing so let's rule out operator error up front. Is it possible there is some fluid leak or exhaust issue with it's location? I moved my alternator with a Jay Racing relo kit a while back because I wanted more room for pipes and turbo and what not but I have read it has some effect on things. The timeline of your failure seems to dictate a much more serious problem though.

We have to look at root causes of premature failure I suppose. Bearing failure due to an overtightened belt. You'd hear that though. Low static battery voltage may cause an overheat which would show as a burnt stator. Lack of ventilation would cause an overheat at the rectifier. A loose belt would cause slipping and force the alternator into a charging mode rather than a maintaining one. This is all of course ignoring any electrical issue.

Your idle battery reading is clearly low. It should be upwards of 13 at idle. Can you verify that all the charge wires are connected proper at both ends of the connection? If it's the factory wire it will be two white wires, as I am sure you know. If one get's half cocked you won't have enough copper to push a charge through, again, overheating.

What is the voltage of the battery with the car off? did you replace the battery when you got the new alternator? Is it possible you are bouncing back and forth between a bad battery and a bad alternator? Battery is low, starts to kill alternator, you replace battery but now the alternator wont maintain charge, kills the battery, repeat?

Just off the top of my head.

/brox
 

SouthCaliVR4

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Jul 31, 2010
Messages
984
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North county San Diego
The alternator in our cars is a strange beasty & it's location is of no help. it will probably test fine cold & as it heats up will drop off in output. first biggie is your turbo heat shield in place? & then as broxmo asked any fluids making their way in? otherwise I have sometimes had to go through a couple rebuilt units to get one that would last & damn near was ready to start carrying a spare. I seem to have a good one now but another consideration is the strength of your battery, with a stocker type batt I ran through alts much faster as hot out put is much lower & again more so at idle, now I have a red top Optima & have not had any issues in a while. To be honest I also skipped on a rebuilt & found an aftermarket new.

Another option is a Subaru alt. higher output & seems to have more heat resistance, likely due to where they are mounted in the subie they get all kinds of hot & probably had to address that. The one I have at the ready is from an outback & looks like it will fit with only minor mods & a change in pigtail but for now my aftermarket new has been doing the job well.
 

prove_it

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Jul 3, 2008
Messages
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Sioux Falls, SD
I have been having some issues with overheat at idle lately. I did forget about our alternators having heat soak issues. My battery tests fine and everything is in place and mostly stock. Fresh air to the alt is same as stock. I woke up today and drove 10-15 miles with no issues and pushing 13.5V the whole time.

I'll check out the wiring, But I do think it is the heat soak.
 

iceman69510

Turn Right Racing
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Mar 5, 2001
Messages
10,964
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Michigan
I would review the condition of your grounds everywhere in the engine compartment. I had a car once that all the lights would dim when I hit the brakes (when that circuit demanded high current). Turned out to be a bad ground under the dash on the brake light circuit.
 

G

Staff member
Joined
Feb 24, 2004
Messages
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Location
zompton
The problem is ac delco and or bad ground. Original Mitsubishi alternators don't have heat soak problems. Nor do bosch & denso.
 
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prove_it

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Any ways of fighting the heat soak?
 

SouthCaliVR4

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North county San Diego
I was looking at a couple different ideas till I quit having to replace every other week. One was to pull the shroud off a bmw 740 alt. it has a duct opening & thought I might run that to my jdm bumper lower vent. Maybe a small inductor fan to keep cool air running at it in the duct. Like a boat blower unit with a micro switch on the ttl to turn it on @ idle. right now I just have doubled up heat shielding & other than stuck in heavy stop & go don't see any low output issues, evn then I just have to turn down the stereo from "ear bleed" level.
 

G

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zompton
Quoting prove_it:
Any ways of fighting the heat soak?



Their is no heat soak.
 

G

Staff member
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Feb 24, 2004
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Location
zompton
Never had it with the stock heat shields installed.
 

ktmrider

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Sep 10, 2007
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Location
Tempe, AZ
Quoting G:
The problem is ac delco and or bad ground. Original Mitsubishi alternators don't have heat soak problems. Nor do bosch & denso.

This.

I went thru the chain-store reman fight last year due to some unfortunate events ( stranded out of state with no tools ). After the third one died, VR crapped out again BTW, I had it rebuilt locally by a shop that uses "quality" components ( Bosch ). No issues or problems since and my brother has put over 3k miles in summer heat on it.

Prove_it, you really should see 14v or higher measuring at the battery even at idle. Like mentioned the grounding system on our cars is nominal plus adding 20yrs of corrosion to the mix does not help. I cleaned all the OEM ground points plus added a few more ( TB to body, body to block, battery to body ) using some 6gauge wire and eyelets. Spent about $10 but made a HUGE difference! All was great until I popped the 100A alt fuse adjusting the belt one day, my alternator died about a month later and started the whole swap dance above.

You already have the DC voltage check done, other things:

1. Look for AC voltage. Higher than 50mV rms usually means the diode pack is faulty which reduced DC voltage output.
2. Grounds as mentioned, clean and add if bored.

Hope you get the system healthy again!
 

SouthCaliVR4

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Messages
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North county San Diego
On the ground issue, Yes!!! I forgot that I also added a dedicated body/engine ground set up using both the terminal options on my optima. top post to the block side post to body. I did this at the same time as My last alternator change & to be honest, may have had as much influence as the alt change out. the stocker cable's body ground is rather unimpressive & prone to corrosion issues.
 

prove_it

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Sioux Falls, SD
All very true and will be tried, but what I'm not understanding is that the issue began at 10 pm, at 85 mph after 300 miles with more than enough airflow to the engine bay. That's when it all began. I've put about 3000 miles on the car since I installed the alternator. I did start having over heating issues prior to the trip, but all within about a week and nothing major. During the overheat conditions the car wouldn't show any signs of low system voltage.

I can see how it's possible that the heat may have damaged a solder joint and it could be an intermittent issue, but why can I go a whole day of driving on Thursday and not have any issues at all.

Any ideas into that??????

I've tested the battery several times in the last few months, even before I hit the road I checked it. It is a cheaper battery with about 3 years of use on it, so I won't completely rule it out.

I've wanted to add multiple grounds for a while now, as I am a firm believer in it anyway, so I'll be trying that out. I do however have doubts to that solving anything.

I have also wanted to heat wrap my down pipe for a while too, mostly to help lower oil temps a bit, so I'll probably try that out too. I'm going to try things systematically so that once I do see an improvement we can have a real answer and it can be added to the info section so more owners can avoid similar issues.

I'm thinking a parts to buy/not buy sticky would be pretty handy to have.
 

ktmrider

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Messages
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Location
Tempe, AZ
It's Basic Electronics 101 for the most part PI. Great read here: click

The lower-quality electronic components used in many remanufactured parts can/will alter their static properties when subject to temperature changes ( both hotter and colder ). Using Ohm's Law triangle in the link above you change R/resistance you get a change to V/voltage. Having done aerospace level testing on electronic components in the past ( +550 F and -100 F ) I can assure you not all parts are created equal. In addition every time you heat-cycle a low grade component you put it that much closer to outright failure due to an alteration of its static properties.

It's what G so bluntly stated twice and I supported so much more eloquently LOL. Yes the alternator lives in a very inhospitable place ( next to DP and turbo heat sources ) however you did not see/hear about them dumping out 300 miles after leaving the showroom either. Most OEM units had long lives due to high-quality internal components.

End result, Economics plays the biggest card. The higher the grade component the more it costs, and the chain stores are about profit margins.
 

toybreaker

iconoclast
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Apr 30, 2006
Messages
3,581
pffft

... leave the geek at the office Mike ...



Automotive charging systems are intentionally temperature compensated.


Quoting factory service manual:


System Operating Voltage, Manual Transmission Regulated Voltage

14.2-15.4 V at -4 deg F
13.9-14.9 V at 68 deg F
13.4-14.6 V at 140 deg F
13.1-14.5 V at 176 deg F




[edit]

eloquently?

wtf? /ubbthreads/images/graemlins/dunno.gif

Let this be a lesson to you...

... more beer and less technical data sheets ...

shits getting to you man. /ubbthreads/images/graemlins/frown.gif







Sorry man, someone had to tell you ... it's what friends do ...

Now close down all your windows, turn your computer off, and go break something so you can fix it.

You'll feel better in the morning. /ubbthreads/images/graemlins/wink.gif
 
Last edited:

ktmrider

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Sep 10, 2007
Messages
3,128
Location
Tempe, AZ
Quoting Toybreaker:
eloquently?

wtf?

Let this be a lesson to you...

... more beer and less technical data sheets ...

shits getting to you man.


Sorry man, someone had to tell you ... it's what friends do ...

Now close down all your windows, turn your computer off, and go break something so you can fix it.

You'll feel better in the morning.

I'm gonna blame it all on Japan, umm yeah that's it! Sake, Kirin, Asahi, fermented rice drinks do wonders for ya... /ubbthreads/images/graemlins/crazy.gif Plus it was morning when I wrote it ( Sunday morning here ) LOL.

Eloquently = LOTS of rice-fermented beverages the night before.

On a more cereal note thanks for the 411 on the voltage vs heat! Now we just need to see what the craptastic aftermarket items are doing... /ubbthreads/images/graemlins/dunno.gif
 
Last edited:

toybreaker

iconoclast
Joined
Apr 30, 2006
Messages
3,581
All kidding aside, there's so much misinformation out there on the charging system of these cars, I've pretty much quit responding to these threads.


Heat shields will increase the service life of the alternator exponentially

Power steering fluid will shorten their life exponentially

Anything but a 90 amp new or reman from mitsubishi is step in the wrong direction. ( One exception to that rule is if you have a cool guy local rebuilder that uses o.e. parts )


In addition, it doesn't even have to come to that...


These alternators will live forever if they are well cared for.

At about a 100k, take them apart, clean the slip rings, install new brushes, and re-assemble.

done


If the regulator was working before, it'll continue to remain functional.

What kills the regualtor/diode packages in these alternators is when the brushes get too short to touch the slip rings. They begin to bounce and arc. The field strength will drop when this occurs, the output voltage will sag and then the regulator will try and compensate by turning up the field voltage to the brushes. The resultant intermittent arcing on the bouncing brushes is what will destroy the regulator/diode package.


cliffs

Preventative maintainance will prevent most of the alternator failures reported on this board.

After the alternator has failed, the reman houses just replace an "elegantly" designed voltage regulator with a piece of crap, replace the bearing with junk, and ship them...

Seriously, compare an o.e. regulator/diode pack with the aftermarket crap, and you'll see why your mileage will vary with these units ...

Many people report going thru two or three remans from the chain stores before they get one that works...

Best to fix the original unit before it's broke. /ubbthreads/images/graemlins/smile.gif
 

ktmrider

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Sep 10, 2007
Messages
3,128
Location
Tempe, AZ
Excellent, thanks a ton John!

And I for one do appreciate ( and pay close attention ) your input and knowledge. Like I have found at work I learn new things each day, regardless of how much I "thought" I knew... /ubbthreads/images/graemlins/worthy.gif
 

prove_it

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Jul 3, 2008
Messages
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Location
Sioux Falls, SD
This is all good info. I wish I had known this before spending 160 dealer cost on my new delco. I'll be checking my cost on a mitsu part tomorrow.
Now I'm really glad I cut my engine mount back, swapping the alternator takes about 45 minutes now. It even comes straight up and out like cake.
 
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