[Coloradude]

I am in desperate need of some help here fellow xterra owners. So I purchased my 05 Xterra S in July of 2019 and ended up having some issues in September. Brake light and battery light came on, car died. It restarted almost instantly and got me to autozone. Battery tested good and alternator had to low of voltage to be tested, meaning the voltage regulator in the alt was bad they said. Got.the car home and it completely died. A couple days later, my father and I put in a new alternator and everything has been good until about 4 days ago (Feb 2019).

Woke up in the morning and brake and battery lights were on. Drove to work in 4×4 with heater and radio(cold snowy day), and did just fine. For drive home at night, had lights heater radio 4×4 on, battery and brake lights still on and was just hoping I could diagnose the lights the next day when I would be off of work.

Nope. As a red light turned green, I pushed on the accelerator, got to maybe 1500 RPM's and then lost acceleration. Still had all electric at this point. I was moving enough (5-10MPH) and had power so I was able to get to a good spot to pull off. Put the car in Park and I was able to rev the engine. Headlights and dome lights still bright. I put back into drive and then back to not being able to accelerate. I began calling for consulting and as doing so, I turned headlights on and off. Battery voltage on my dash started dropping from its normal level (about the middle) and the VDC OFF, SLIP, AND ABS lights illuminated while meter still draining. Meter drained to 10V before I turned the car off which had been maybe 2 minutes.

I had to wait for a friend for help and walked to the gas station ( was gone about 30 mins). Got back to car and before trying to jump start, I just turned it over and it started. On start, volt meter on dash at normal level. I moved about 40 feet and then lost acceleration and battery started draining again. Car died. We jump started it, and same thing. On start, at normal volt reading but as soon as I moved (this time only about 15 feet), no acceleration and battery dies.

The next day, we pulled the battery and took it to autozone and at resting it put out 12V and a 29% charge. We charged it up and then it had 12.7V 100% charge. We put the battery back in the Xterra and got it to autozone. On this test, the battery was giving out 12.36V while running and 12.7V not running. While running they switched to the test for the alternator and it said that there is to low of voltage.

I am at a loss here. We have a warranty on the alternator since we just replaced it, so we are going to do it again. But I fear there is something causing the death of the alternator. Perhaps something with the voltage variable control system aparatus that exists on the battery terminals? Or the alt fuse? Or even ground wires on battery or alternator? Just my luck there is about 1ft of snow on the ground and counting so as soon as I can I am going to get my baby fixed but I need some brains to bounce ideas off of! Thanks guys!

 

[LNXPenguin]

It sounds like you may have an intermittent grounding issue. I would check the chassis grounds and cables for corrosion, rust, other things that may cause high resistance. The stock battery terminals are also notoriously bad, I would clean them thoroughly to test, and replace them for sure if that turns out to be the issue. It seems when you are stationary, there is adequate ground temporarily then the second you move, the ground path gets iffy. From the battery, there is 1 bolt that ties the negative cable to the body, then another that goes to the engine block. I would disconnect the cable, sand the contacts and the mating connection points on the body and see if that helps. Several of us here have beefed up our alternators for various reasons, and replaced the ground cable from the battery completely, that cable is undersized to begin with in my opinion. 1/0 welding cable will fit through the current sensor with a friction reducing fluid and patience.

You mentioned that the alternator was replaced recently, did you clean the mounting bracket and get the metal shiny before installing the new alternator? You could be getting a high resistance in that ground path if the metal to metal surfaces are corroded. If they salt the roads there, the salt could lead to corrosion, but also, could increase conductivity just enough to let current flow until the saltwater dries up and causes the intermittent problems you are experiencing, hence it runs after sitting for a bit then cuts out soon after getting it restarted.

The second issue could be that you have a bad diode in the alternator, which is causing it to drain the battery instead of charging, more unlikely, but not completely out of the question.

 

[Coloradude]

I will be sure to check all the chassis ground conmections for rust and what not as well as re evalutate the battery terminals. We visually inspected and cleaned the battery terminals and they seem clean and trustworthy. I also will do the removing of the ground cable on the battery and sand the contact and mating connection points and maybe even replace it since that wont be much extra work anyways and hopefully is a player in this. We did clean the metal bracket for the alternator as well as the connecting pin/harness, but I will be sure to make sure its as clean as can be when we put this 2nd alternator on. Do you know if there is a way to test the functionality of the voltage variable control system a.k.a as the box attached to my positive battery terminal? Does everybody's battery have this? From what I can find online it acts as the first line of defense voltage meter and when it fails the voltage meter in the alternator is suppose to take over? Also, am I wrong in the understanding of how it works? Appreciate any and all responses, thanks!

 

[IntellectualRedneck]

I experienced similar issues when I had a weak battery, and then then same issues again when I had a poor connection at the negative battery terminal, which caused the alternator to toast. To test, I just put a multimeter on the battery and had someone start the X, and then put electronic load on it. When the X starts up, the voltage regulator is in open loop at 18V, and after a warm up period of about 1 min, the loop closes, and the voltage regulator is fed back by the ECM and should put out 13 - 14 V if the demand is needed.
@LNXPenguin has some good advice, I'd start with that.

 

[Brunnie]

Does the positive connection on the battery have a shim on it? Nissan positive cables are notorious for being too large for the post on the battery, and thus require a shim.

 

[Coloradude]

So on a good alternator, when I start my Xterra, after about 1 minute of warm up, I should be getting between 13 and 14V right? More on the 14 end with no load and more on the 13 side with load? And anything under that indicates that the alternator isnt charging the battery, right? I'm just trying to fully understand this system and process. Thank you guys for your suggestions and input! Definitely am going to re clean the batt terminals, ensure the shams are snug, take off the battery ground cables and clean the connection points and the body and see what I've got. Its going to be a couple days sadly. What do you guys know about the voltage variable control systems?

 

[MeHere!]

Does the positive connection on the battery have a shim on it? Nissan positive cables are notorious for being too large for the post on the battery, and thus require a shim.

This...I had similar issues, then noticed the terminal kept coming off, until I wedged a paper clip in there...worked like a charm till I could upgrade the connection

 

[LNXPenguin]

I would suggest the military type terminals, they clamp on real secure and allow you to connect a lot of stuff to the battery through a nice solid 3/8" bolt, which can be swapped for a longer one to add more connections

 

[gtitonta]

@ Coloradude your friend or family do not have current clamp? Simply hook current clamp to positive side of cable from alternator and measure it. If you can not see any current, definitely either connection or alternator problem. normally, the voltage will goes up over 14V within 5 seconds or so once you start engine normally. It really depends on how much battery power left and outside of temp.
If I am you, measure current with current clamp to see current coming from alternator or not. If not, check connection at positive side of alternator. It is kind of pain, but you can take out passenger side of tire and remove inner splash guard. Then, you can see and access cable. see this thread how to do it to access to alternator. (How-to: Alternator Replacement - 2005+ VQ40DE - PBR).

Then, check the main ground which is located at engine block. you can just follow ground cable from battery. to make sure connection is ok or not.

good luck.