Alternate Alternator Upgrade - Nissan/Infiniti

[Bob Weir]

Fortunately, I never had a problem with battery & alternator and insufficient power running AC & lights. I've always had Deka 2nds from the factory lasting about 4+ years and I was mindful of fixing grounds and replacing wire when needed.

Ed's comment
<One possible contributing factor re Scorpio versus XR voltage is the rats nest power leads at the Scorpio positive battery terminal each sapping small but cumulatively significant decimal point volts.>

Maybe I found a better way to hook em up - see pik

[brokencase]

Secind pic waiting at bank drive thru, in park w/injun running, blower on low, radio on, no other load on battery.

First pic driving from bank @~25 mph, blower on low, radio on, (actual V registered when I clicked the photo was 13.6v).

YMMV

..and what with the A/C clutch engaged and blower full blast? ...and while you are at it - run a jumper to the front electric fan to force it on.
Then you will see...

Oh yea... and install a heated seat kit like I did. What is that? Maybe another 8 amps?

No regrets regarding the Titan alternator upgrade.

[Ed Lijewski]

Those loads are mostly temporary. No one keeps heated seats on for more than few minutes, ditto for blower on high speed, ditto for rear window defogger (if they're alert re the defogger). ABS pump running is also temporary, same with windows, sunroof, power seats... So the concern will be that engine rpms rise enough for long enough with heavy power draws to enable battery charge replenishment. (Note that the '88 Scorpio condenser fan radiator switch and fan wiring is two-speed, low and high, with high only actuated if either a/c pressure rises to set level or cooling system temp rises to set level.)

I've noted multiple times here that on my XR those loads are handled fine by its alternator. The XR has a cooling fan (old style, draws big amps) and a condenser fan that has slightly more efficient fan blades. Both XR fans operate with the engine warm and a/c on. With blower on medium (high setting doesn't really cool faster and makes objectionable air noise) the XR voltage reading at idle might be in lower 13s, rising to mid 13s with car underway. I don't have pics of that but trust me, I watch voltage readings more than tach or speed readings under those scenarios.

My posts on this are to underscore that there must be a reason why the XR system more capably handles real time power loads while maintaining relatively steady voltage, while the Scorpio system struggles to do that. Both XR and Scorpio alternators are 90 amp Bosch units of the same mid-late 1980s period.

I'll also note here that I have a suspicion that the cigar lighter voltage readings are (slightly?) less accurate than my XR's voltage readings which are hard wired to the battery positive terminal. The cigar lighter element has typical corrosion on it.

YMMV

[brokencase]

The A/C is not a transitory load. I recall a 3 hour trip up to the Poconos where I was running the A/C and monitoring the battery voltage and it just kept dropping. I finally shut off the A/C so as to ensure I would make it to the final destination.

There is no big voltage drop to the cigarette lighter. It's a high current circuit.

My experience with the two Scorpios that I have owned is that they both went through batteries more quickly than they should have.

On my current Scorpio I put a Walmart battery in it when I bought it and it only lasted 2 years. I did a warranty replacement and the second one one was about to go when I installed the Titan alternator.

With the Titan alternator and a new AGM battery I finally feel the issue is licked.

There wasn't anything wrong with the Bosch unit. I tested the diodes, windings, and everything. Installed the new adjustable regulator and I could see that it did raise the maximum charging voltage. But it still did not have enough juice at low rpms and when loads were placed upon it.

The Bosch unit is just marginal.

[Ed Lijewski]

Certainly battery integrity plays a major role re what we're discussing. I've had good experience with Walmart batteries over years (only bought one other kind once in an emergency...it sucked), for both XRs and Scorpios. Although, my last/current Walmart XR battery doesn't have the oomph of the battery it replaced when new and over ~3-4 years of usage. That one was a 5 year warranty battery; I brought it in just for testing but learned Walmart stopped offering that service during its pandemic retreat. I was told they no longer stock 5 year warranty batteries, and of those on shelves of my fitment there was only the 2 year warranty unit. I recently had replaced the starter in that XR, but the 2 year battery doesn't spin it as fast as the 5 year unit did.

I don't doubt that battery purchases can be a crapshoot. But Project Farm on YouTube compared several batteries against several measures and Walmart's Everlast brand came in ~second overall but first (IIRC) factoring in unit cost.

The experience with your Scorpio batteries is at odds with my long term '88 and my 2 years old '89. I keep each XR and Scorpio on a battery maintainer when not in daily use.

Logically, powering the a/c clutch and condenser fan on a highway/country lane trip shouldn't result in inadequate alternator output. I have no clue why that occured for you. Well, maybe I have a correlative experience. Once in an XR on very congested city street traffic, running lights, a/c and blower on low removing interior humidity, I saw the voltage dropping at idle and failing to rise when traffic got moving a bit. Long story short, I turned off all power draw when I could in traffic and made it home. I had a reman alternator in my stash and installed it and output V returned to normal.

I may be mistaken, but I don't recall that you replaced alternators in your Scorpios until the Titan unit.

Re the cigar lighter, take a look at the heating element. Mine works (amperage) but the element is crusty and crusty surface where voltage is being tested does result in iffy readouts. The reading on the Chinese meter in my photo jumps around in decimal point numbers unless I press it more firmly in and/or rotate it, but those actions don't clean the element. Accurate V or Ohm readings require clean surfaces for reliable readings in decimal points.

Battery prices today encourage bargain shopping. I think Project Farm may have used a longer than 2 year warranty battery. My next replacement may have to be another brand no matter price if Everlasts in my needed size with more than 2 year warranty aren't available.

Again, I'd buy a Titan alternator fitted for install based on your experience.

https://youtu.be/h7rTcBanpMk

YMMV

[DPDISXR4Ti]

I just bumped this thread as it had never before occurred to me that when doing a 3G alternator swap you also take the instrument cluster out of the picture as a critical path of the charging circuit...

viewtopic.php?f=30&t=22201

Having just gone through a mess with the Scorpio instrument cluster, I'm thinking it should be a similar goal with an alternator swap in the Scorpio to NOT be dependent on a functioning instrument cluster.

I haven't even gone back to study this Nissan alternator swap yet, but I'm wondering if it does already address this. Yes, no, maybe???

[brokencase]

Brad - The only thing in the cluster that goes to the alternator is the warning light. Generally not a big deal.

Ed- The only thing that is different regarding my setup is that I run the aftermarket cooling fan when the A/C is on. It only draws 6 amps.
I also saw the Project Farm vid, but it was after I had purchase the Walmart battery.

It is interesting to look through Rockauto and see how the alternators have been uprated over the years for other cars.

For example..
1989 Mustang had a 75 amp alternator.
By 1995 they had a 130 amps.
in 2010 they come with 150 amps.
in 2017 it is 175 amps

Taurus is the same way. A 2017 Taurus has a 200 amp alternator BTW.

It is no doubt the more recent vehicles have higher electrical demands, In dash infotainment, auto start/stop, etc.

But I don't think there is a big difference in electrical loadings between an '89 and a '95 Mustang. So why did it get uprated?
I think it was just because things get improved over time as they went through a new design cycle. The designer's were always looking for more output in a given size package and through design improvements they got it.

So from this perspective the Titan alternator upgrade is a wise improvement.

But I would even take the '89 Mustang's 75 amp alternator over the Bosch 90 amp unit any day. Because I know the Bosch unit has poor output at low rpm and I'm not the only one who has made this observation.

[Ed Lijewski]

Still no explanation for the good performance of the same Bosch unit in the XR system...

YMMV

[DPDISXR4Ti]

Brad - The only thing in the cluster that goes to the alternator is the warning light. Generally not a big deal.

Understood, but isn't it true that a failure of that exciter circuit to the cluster will result in a no-charge condition of the alternator? I know that is the case with the XR, which is why a resistor was added on the later clusters so that a failed bulb would not result in a no-charge condition. Given the issues I'm having with my Scorpio cluster right now, I believe on the Scorpio too, if the exciter circuit fails, the alternator does not charge the battery.

[Ed Lijewski]

Correct. Another identical similarity of both XR and Scorpio charging systems.

YMMVZ

[brokencase]

Understood, but isn't it true that a failure of that exciter circuit to the cluster will result in a no-charge condition of the alternator?

It's just a light. Failure would mean the light is blown. Yes it is a minor hassle if the light burns out and that you have to pull the cluster, change the bulb, to get the alternator to work. But it practically never happens. Remember - the bulb only lights momentarily until the car is running.
It is a very low duty cycle.

But if it did then I'm glad I am forced to fix the light, rather than if you somehow managed to get a 3G installed on your Scorpio and the dash light fails and you never get around to fixing the dash light because you feel that it is "optional".

As a temporary workaround - You could always bypass the dash bulb and wire your own bulb to the alternator from ACCESSORY +12V.
But it is easier to just replace the bulb. Not sure, but I'll bet I can probably replace the alternator bulb without unplugging the cluster.
At this point though, I've pulled Scorpio clusters so many times I think I can do it in my sleep!

Now - if you current problems with your cluster prevent the alternator from working...all I can say is you have bigger fish to fry. Changing to a 3g alternator is way down on your list of things to do...

[Ed Lijewski]

On XRs some owners have reported the Batt light failed; I haven't heard of a Scorpio owner reporting that possibly because Scorpios haven't been driven as much as XRs (so far...)

For me the light is valuable not only when turning off to indicate the alternator is charging but when dimming faintly while the engine started or is/has been running to indicate a charging system issue (alternator or battery or something else, e.g.). That scenario has been reported often enough by XR owners.

I think the value of the Batt light equals the value of the oil pressure light in regards to the alerts each sends.

YMMV

[brokencase]

Just as an aside..

When I first received my current Scorpio there was one of the cluster lights blown out. So I decided to change all the bulbs to LED's
In fact, I changed a lot of lights to LEDs. Footwell lights, door jam lights, over head console lights, etc.. I bought most of the LEDs from China.
BTW - if you are considering doing this - make sure you get the "warm white" style bulbs.

Anyhow - I systematically changed all the bulbs in the cluster to LED's. It was an involved task, I had to figure out where + and - was for every socket. I got through all of that, but I had forgotten about how the alternator light works. So it too was also replaced with an LED.

The symptom of an LED substituted for the alternator light is as follows... You start the car and the alternator light does not go out. You rev the engine up and then it goes out.

Anyhow..it was fun tracking down that issue.. It is yet another cause for my repeated R and R of the dash cluster!

[Ed Lijewski]

The symptom of an LED substituted for the alternator light is as follows... You start the car and the alternator light does not go out. You rev the engine up and then it goes out.

On my '88 I installed a rebuilt alternator. That unit turned out to have a higher cut in rpm than the OEM one so on start-up and run the Battery light remains Illuminated until the accelerator is depressed to raise rpms to ~1200 level.

YMMV

[brokencase]

Still no explanation for the good performance of the same Bosch unit in the XR system...
YMMV

I'll venture a guess. Take a look at this chart..

galts.jpg

You'll notice that the 95 amp 3G alternator actually puts out less than the 75 amp 2G alternator does at 1000 rpm!

Now, I don't know what the Bosch alternator curve looks like but from what I have heard it is probably something like the 3g 95 amp curve. I searched the web but could not find one.

But you can see the curves are very steep for the lower output alternators at low RPMS. The bigger alternators can make 50 amps or more at idle.

So a Scorpio idles around ..what 700 rpm? ... and the XR4ti idles what...around 1000rpm?

Even that 300 rpm difference could make "tens of amps" difference between the two cases.

Also be aware that these curves represent the max output the alternators can provide at a given rpm. The load and regulator define the actual output. And sticking a 130 amp alternator in has nothing to do about ever using 130 amps. Its about having 40-50 amps available at idle