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Discussion Starter #1
Hi,

I've been fighting the battle with Stanza electrical for years now. I'm on my third alternator, I've cleaned all the pulleys and replaced the belts. It finally isn't slipping and when the engine is at decent rpm >1200 it does ok.

I've come to the conclusion that perhaps Nissan didn't put as big an alternator in as they probably should have. According to thier specifications, they say "hot output current" is >50 @ 2500 rpm and >60 @ 5000 rpm. I figure they mean alternator rpm and not engine rpm, but it doesn't say specifically. I also can't find any information about the engine to alternator ratio.

The issue is this, if I have any sort of accessory load on and I pull up to a stop or wait at a traffic light, the alternator is easily overwhelmed and the car is pulled down to battery voltage.

At 750 engine rpm I just don't think it is making enough power. And on top of that, I usually have my foot on the brake which is another 9 A in brake lights and possibly 4.5 A in a on/off turn signal.

I've made some measurements of the electrical loads in an attempt to see if any are excessive so I can reduce them:

Key=Accessory 0.5 A
Key=On (not running) 4.1 A
Fuel Pump by itself (part of key=on) 3.0 A
Key=On (engine running) 6.0 A
Headlights=On 14.3 A (left main beam 4.0 A, right main beam 4.2 A)
Brakelights=9.8 A
A/C=10.0 A (measured through fuse box, probably include A/C radiator fan)
Radiator Fan=unknown haven't measured it yet.
Front Wipers=6.0 A
Rear Wiper=1.5 A
Radio=350 mA
Interior Light =0.5 A
Fan=Lo=3.3 A, Med1=5.0 A, Med2=9.7 A,Hi=15.9A

The problem is that these can add up pretty quickly and easily overwhelm the alternator at low rpm. Since my Stanza has a battery monitor (the one at walmart for $17 is absolutely wonderful!) always plugged into the cigarette lighter, I always know what is going on with the voltage.

My question is - has this always been a problem with the 86 Stanza? Does it just not have enough power at idle to supply accessories? At night you can easily see the headlights dim down when pulling to a stop and it drops the voltage to the low 12's.

I don't know of any more powerful alternator and I'm not so sure adjusting the pulley size on the alternator is a great fix as it might provide more voltage at low rpm but run too fast at higher rpm's.

My only idea is try to to reduce the load. I admit that in the summer when it is hot I want to run the A/C which is 10A + 9.7 A or 15.9 A for the fan depending on its setting which is 20 to 26 A and is a huge load for the car to keep up with when idling. It does fine on this when in motion (engine above 1000 rpm).

Maybe this is normal for a car to drop voltage when idling, dropping to below battery voltage (meaning current is being pulled from the battery) doesn't seem normal to me although maybe it is.

I'm going to try replacing the lights except headlights with LED's. They consume 96% less electricity and could potentially eliminate a big current draw. I am especially hopeful that the brake lights being chopped down from 9.7 A to much less than 1 A will make a big difference when stopped at a light or in traffic.

I wonder if the manual version of these was not as affected by this as they are supposed to idle around 900 instead of 750.

My other technique to deal with this (besides turning stuff off when I slow down or stop) is to take the transmission from drive to neutral. This allows the engine to idle around 1000 or 1100 and the engine does alter its idle based on its electrical load which is good. I just don't see how that feature helps when it is in drive because the transmissioin holds it down to 750 regardless. I don't want that to cause undue wear though so I am hesitant to switch from drive to neutral on a routine basis everytime I pull to a stop.

All comments and suggestions welcome!!

Thanks,

Alan
 

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Have a 5 speed 1986 Stanza wagon and it has been through a bunch of alternators. They tend to overheat and burn out. I replaced it myself at least twice. My mechanic once. I finally had Nissan replace the the alternator a few years ago. It died 12.001 months later! Got Nissan to replace it after a major bruhah. It's been fine since. All the replacements were rebuilts. Couldn't get new units. This car only has 119,000 miles on it and is my winter/ dump car now and OEM parts are hard to get for it. Perhaps a replacement from Advanced Auto Parts which claim superior new units would help.
A/C has long since died and no longer loads the alternator as you experience. Also, since its a 5 speed, I don't have the A/T loading the engine at idle. Keeping the idle at 1,000 rpm helps. I also use one of the LED voltage indicators plugged into my cigar outlet.
 

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Discussion Starter #4
Hi,

rjbasta: Those LED plug in voltage indicators are a must, that is for sure!! I've been debating just not using the AC, but it gets pretty hot here in the summer and it is nice to turn on.

NissanPartsDept: I wonder if the OEM models had a better IC regulator in them than the one's I've been getting from NAPA. My engine seems to idle around 650-700 rpm and the alternator just doesn't produce enough power to run the A/C at that speed. I considered putting a smaller pulley on it, but didn't know if it would be spinning too fast when the engine is going faster. The service manual says 60A for the alternator, but I think the last one I bought said 70A on it. With the AC, fan blower high, both radiator fans running, engine running, maybe headlights too, I think I measured 77A with my clamp meter a year ago. Then again, these fans and parts are very old and are probably pulling more current than originally designed. Do you happen to know how much current the radiator fan or compressor fan should pull? I don't think I saw that in the service manual.

Thanks,

Alan
 
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