Disabling the "intelligent" alternator charging

95maxrider

95maxrider

Member
I think I'm going to disable the "intelligent" (stupid) alternator charging system on my 2011 FX50, but I wanted to run it by everyone here in case they have any insight.

The intelligent charging isn't explicitly spelled out anywhere from what I can find, but the general consensus of how it generally operates on other Infinitis/Nissans is that the ECU tells the alternator when and how much to charge, as opposed to letting it just charge all the time, in an effort to improve fuel economy. Some people say that the system won't turn on the alternator until you've driven 8 miles. You can probably see how this could be a problem if you don't regularly drive more than 8 miles. There is also a voltage sensor on the battery negative cable that feeds info to the ECU. It's not clear if the ECU will tell the alternator to charge if voltage drops below a certain level (I would think that it would) or if it's really all down to driving more than 8 miles.

Here's a thread on the Armada forum discussing the issue:
Smart Alternator ???

And here's a video of a guy showing how to disable the dumb charging feature:

Here's info from the FSM for my 2011 FX50:

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So, just like as shown in the video above, the wire that needs to be disconnected is pin #76, the only difference for our cars is that instead of it being a yellow wire, our wire is either purple for the 5.0 cars, or violet for the VQ cars.

Since I don't care about taking a 0.001 MPG hit from having the alternator run all the time like it should, I think I'm going to try this out. I just can't figure out if I actually need to pull the wire from #76, or if I can just unplug the sensor from the battery ground cable. What do you think?
 
Following - looking forward to updates. I have a 3.5 mile drive to work so I rarely drive past 8 miles in a single trip.
 
I read through a different and very long thread on the Armada forum:
Armada (and QX) charging system problem fix

And basically yeah, you can just unplug the wire harness from the sensor on the battery negative cable. This prevents any voltage signals from getting to the ECU, which then tells the ECU to let the alternator determine how it should charge. Removing the wire from the IPDM as described above will get the same end result, but it's quite a bit more work. Now, some people mentioned that disconnecting the voltage sensor may throw a hidden code for some module, but it won't trigger a CEL. Other people said that it doesn't. Since I recently got a more powerful scan tool, I should be able to test this out once I get my car back together.

I'll post back up in here after I do some testing on my car.
 
Wait, I'm confused. When my battery dies and I jump start it, leaving the engine running for a hour adds charge to battery. And it's not moving.
 
That's why I said at the beginning that I'm not 100% sure of how/when it decides to let the alternator charge. Even if you don't drive 8 miles, I would imagine there is some threshold, like 11.8v, where it would tell it to charge.
 
I read this thread after 2 dead batteries and a new alternator. I was only receiving 11.6v at the b-post of the alternator and at the battery. After lots of troubleshooting the fuses, wiring, grounds and replacing the 3 prong connector I decided to test this bypass. I got some of the wago connectors for the connector install so it was easy to test. I just jumped pin2 over to pin1 and started the engine. That fixed it. Im now receiving 14.7v at the batter with engine running constant. This did present 1 unfortunate result though. The parking brake light and battery light are on on the dash. This is due to abnormal voltage reading and the parking brake light is somehow tied into the same system I bypasses so...w/e. Its running now. BTW its a 2014 infiniti qx70.
 
Ifindit said:
I read this thread after 2 dead batteries and a new alternator. I was only receiving 11.6v at the b-post of the alternator and at the battery. After lots of troubleshooting the fuses, wiring, grounds and replacing the 3 prong connector I decided to test this bypass. I got some of the wago connectors for the connector install so it was easy to test. I just jumped pin2 over to pin1 and started the engine. That fixed it. Im now receiving 14.7v at the batter with engine running constant. This did present 1 unfortunate result though. The parking brake light and battery light are on on the dash. This is due to abnormal voltage reading and the parking brake light is somehow tied into the same system I bypasses so...w/e. Its running now. BTW its a 2014 infiniti qx70.
Click to expand...
Also worth noting that id broken down twice, two tow charges...before figuring out it wasn't the alt, battery, or wiring lol
 
So I played around with my 2011 FX50 and can report some updates. With the car in the stock wiring configuration, upon starting the car I would see 14.0v at the OBD2 port, but after about 10 seconds it would drop down to 13.0v and stay there for about 8-10 minutes of driving, after which time it would kick up the voltage to 14.0v. Note, that I only drove 2-3 miles in those 8-10 minutes, so it seems to be more time-dependent than mileage-dependent before it decides to fully charge things. Because this is a surefire way to kill a battery, I unplugged the wire harness thing at the negative terminal. Now the car is steady at 14.0v no matter what I do! The only downside is that this does trigger two silent/ghost error codes about the intelligent charging system, but they don't trigger the CEL. You would only know they're there if you run a scan for codes.
 
I've replaced several AGM batteries in 2009 FX50 over the years, well before they should have been dead. I thought I was going to need a new battery a few months ago and I found about about this current sensor and disconnected it. Now the battery seems to be charging the way it should and its running great. Typically see 13.5v to 14.1v on my voltmeter now when the engine is running.
 
2009FX50S said:
I've replaced several AGM batteries in 2009 FX50 over the years, well before they should have been dead. I thought I was going to need a new battery a few months ago and I found about about this current sensor and disconnected it. Now the battery seems to be charging the way it should and its running great. Typically see 13.5v to 14.1v on my voltmeter now when the engine is running.
Click to expand...
Did you have the brake and battery light come on on the dash after only disconnecting the sensor?
 
Ifindit said:
I read this thread after 2 dead batteries and a new alternator. I was only receiving 11.6v at the b-post of the alternator and at the battery. After lots of troubleshooting the fuses, wiring, grounds and replacing the 3 prong connector I decided to test this bypass. I got some of the wago connectors for the connector install so it was easy to test. I just jumped pin2 over to pin1 and started the engine. That fixed it. Im now receiving 14.7v at the batter with engine running constant. This did present 1 unfortunate result though. The parking brake light and battery light are on on the dash. This is due to abnormal voltage reading and the parking brake light is somehow tied into the same system I bypasses so...w/e. Its running now. BTW its a 2014 infiniti qx70.
Click to expand...
You know, I was troubleshooting an alternator issue on my other Infiniti, and it too was throwing both lights on even though my voltage was good and my alternator passed a load test. I ran through the troubleshooting steps in the FSM, and it turned out that the alternator fuse was blown. Once I replaced the fuse, the lights went off!
 
Ifindit said:
I read this thread after 2 dead batteries and a new alternator. I was only receiving 11.6v at the b-post of the alternator and at the battery. After lots of troubleshooting the fuses, wiring, grounds and replacing the 3 prong connector I decided to test this bypass. I got some of the wago connectors for the connector install so it was easy to test. I just jumped pin2 over to pin1 and started the engine. That fixed it. Im now receiving 14.7v at the batter with engine running constant. This did present 1 unfortunate result though. The parking brake light and battery light are on on the dash. This is due to abnormal voltage reading and the parking brake light is somehow tied into the same system I bypasses so...w/e. Its running now. BTW its a 2014 infiniti qx70.
Click to expand...
I should also add there are multiple ways to skin this cat for ppl reading this in the future. Unplugging sensor didnt fix it for me. Dash lights came on. You can do a few things...you can get rid of smart charging by removing the wire from the ipdm, and jumping the wire from pin2 to pin1 at the alternator. You could also quick-splice with a resistor the jumper wire and run and extension wire to a ground on the engine block. This tells the ecm that the voltage of that sensor wire isn't 12v anymore but more around 6-8v which would cut the dash lights off, give u 100% alternator power and bypass the smart charging system because the ecm doesnt recognize an "abnormal voltage" on the battery anymore. The battery current sensor retails at 444 bucks. U can find thru advanced at 283 bucks...or like me today...go to junkyard and pull one off a 05 altima for 5 bucks lol. I reversed my jumper and replaced sensor and enabled the smart charging system again...whichever way u want to do it...there's a fix from multiple angles for cheap. Hope this helps someone.
 
95maxrider said:
So I played around with my 2011 FX50 and can report some updates. With the car in the stock wiring configuration, upon starting the car I would see 14.0v at the OBD2 port, but after about 10 seconds it would drop down to 13.0v and stay there for about 8-10 minutes of driving, after which time it would kick up the voltage to 14.0v. Note, that I only drove 2-3 miles in those 8-10 minutes, so it seems to be more time-dependent than mileage-dependent before it decides to fully charge things. Because this is a surefire way to kill a battery, I unplugged the wire harness thing at the negative terminal. Now the car is steady at 14.0v no matter what I do! The only downside is that this does trigger two silent/ghost error codes about the intelligent charging system, but they don't trigger the CEL. You would only know they're there if you run a scan for codes.
Click to expand...
Do you happen to have a pic of the wire harness thing? I don't want to unplug something else lol. Though this dead battery thing hasn't happen to me yet (newer battery), I can feel that the car is struggling to start in the mornings now that it is winter here.
 
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