Dear all,
My Infiniti m56x 2011 had a problem with voltage (it was producing 11.2-12 volts) which was a bad indicator. So I took it to a service and they repaired the alternator/generator module.
Now it produces 13.1-13.3 volts.
Still I think that 13.3 volts is not the correct value that my car should produce. I have asked several nissan owners and all of them had 13.8-14 volts.
Please can you share with me your results ? specifically 5.6 liter models.
Thank You in advance

You may not have any actual issue, the M56's have "smart" alternators controlled externally by the IPDM to respond to load. However, this can cause battery-depletion issues if your car makes a lot of short trips. If so, there's a simple fix that puts the alternator on "internal regulation" (14V fixed-output) and removes the IPDM from the loop. See this thread:

topic623786.html

PS - For anyone else reading, this approach will work on any Nissan product with an IPDM-controlled alternator. Late model Armadas, for instance, often have similar short-trip issues. The same fix will work, although the exact wire color and position will differ. It may or may not work on models with an ECM-controlled alternator, I don't know anyone who's tried it yet, but it can be used freely on any model using the IPDM.

THank You for a quick reply.
So for my 2011 M56x can we state that it is an IPDM-controlled ?
And returning to my first question. As you said I might not have any actual issue, do you mean that 13 volts for my model is a good indicator ?

You're most welcome. To my knowledge, all the M56's have IPDM control. Since it's load-based control, the voltage you see at any given time will depend on the electrical load and the battery state of charge. Generally speaking, if you enable the AC, turn the blower motor on high, and turn on the high-beams, the load will kick the alternator into "high gear" with 14V output. If so, the system is probably working as-designed.

If I were to give you a quick answer, it would be 9.8 volts-14.8 volts for the M56 I drive most.
I would like to be a little more specific though.

So apart from the low-ish voltage readings, did your car exhibit any other symptoms? Did your battery keep dying, or what exactly brought your attention to the charging system?
Unless I missed something, it seems like you have only replaced the alternator but not the battery itself, correct?


***
For example, here are results from my 2011 M56S with around 95k miles. It has a 750CCA AGM battery from NAPA that has been in use for approx 2 years. I don't have immediate access to the exact duration and mileage, but the car has been operated in the midwest since the battery replacement.


I got these results on a Fall day with an ambient temperature of 32 degrees F.
I collected 4 types of voltages:

1. Battery voltage before starting the car
2. System voltage while starting the car
3. Voltage with the vehicle at idle, and no loads
4. Voltage with the vehicle idling, with electrical loads

I tested the vehicle at these different states:

1. At the first start of the day after the vehicle had sat undisturbed for a day.
2. Immediately after test #1, I turned it OFF then ON again.
3. After I drove around town, and made sure I did not cross the 8-mile mark. This was a normal commute with traffic lights plus a few shut-offs & start ups as I ran errands.
4. After I drove further out of town, and accumulated over 8 uninterrupted miles.
5. Immediately after testing #4 above, I shut it OFF then ON again.

I did these many tests to show that different testing and operating conditions could result in slightly different results from one vehicle to another, and even within a specific vehicle.

The battery tester I bought from AutoZone would indicate normal or high for certain voltages, so I made a point to note that down in the chart. It never once showed low.
For the sake of data integrity I find it beneficial to post the entire chart rather than just handpicking my favorite combination of numbers.

I should also add that this car has never suffered a dead battery with the current battery.

It still has the original VK56VD starter, which sometimes gives me a click-no-start condition. I plan to replace it over the winter and will be eager to repeat the preceding tests to see what effect the new starter has, if any.

The car is still running the original ECM-controlled alternator setup from factory.
Although at different times I have exclusively driven the car under 8 miles in an attempt to fatigue test it, I have not suffered the same issues some members have reported with their batteries dying.
Granted, I wasn't driving around with a battery tester those days, but I am the kind of guy who gets in the car and leaves my convenience features all set to AUTO and that prevents inadvertently bypassing any of the car's operational logic.

Well done, Ed.

Man this is extremely helpful !!!! THanks a ton for that research you have done there. Amazing.
I have acctually suffered the well known issue of battery replacement. I did it like 3 times already. I also replaced the starter as it was dead already.
I started to notice my problem with my low voltage when I installed a video registrator with a small ups (backup battery) and after some time the battery of the registrator was getting low all the time as it wasnt getting enough charge. So I tested my voltage when the car was running and it was 11.9 - 12.3 max.
I went to a service, that worked on my alternator, changed some parts and now it produces 13.2 max.
As I saw your research on voltage in various conditions I now see that I have an alternator problem for sure.
I am going to have it repaired now.
THanks again

Thanks guys, glad my results offer some point of reference.

asafinar wrote: ↑

Wed Dec 09, 2020 6:41 am

... I did it like 3 times already. I also replaced the starter as it was dead already.
I started to notice my problem with my low voltage when I installed a video registrator with a small ups (backup battery) and after some time the battery of the registrator was getting low all the time as it wasnt getting enough charge. So I tested my voltage when the car was running and it was 11.9 - 12.3 max.

That's quite a lot of work you've put into the starting & charging system!

Have you ever tried to disconnect the UPS to see if the problem goes away? I am curious if it is wired in a way that basically screws you over twice.
By being a parasite to the main battery, while also telling the alternator that it doesn't need to charge at full capacity.

Barring that, I would try the fix that others have been talking about to see if it stops the premature battery deaths. howto-disable-ecm-controlled-alternator-t623786.html

Also, I am not discounting the possibility of landing 2 bad alternators, especially if your replacement is an aftermarket unit. Nissan already gave us a questionable starter for the V8, so I wouldn't be surprised if they started offering a "revised" replacement alternator for these cars.

Jokes aside, for reference, the OEM spec for the system with the engine running is a nice and tight 14.1 volts - 14.7 volts.
The "smart alternator" stretches that to range from 11.4 volts to 15.6 volts.