This is a continuation and distillation of this thread: https://www.thenewx.org/forum/56-rugg...talled-10.html
Update, 4/3/18: awaiting replacement sense wires to test.
Here is our data @SteeevO
We are trying to collect as much data to send to Rugged Rocks and DC Power to alleviate a voltage fluctuation we are seeing at idle.
Known members with Rugged Rocks/DC Power Alternator installed + output:
- On cold start, we are seeing initial voltage around 15.2v.
- At engine idle, there is a wide fluctuation in voltage. With the most extreme case being 11.7-14.9v. Mostly 13.7-14.3v at idle (LNXPenguin's rig) 13.67-14.85 (KingTruc's Rig).
- On my vehicle, at night, idling with just stock headlights on, you see noticeable dimming and brightening at stop light. Voltmeter shows fluctuating voltages.
- Video from @kingtruc
showing example of fluctuations
What we know:
- Crankshaft pulley diameter: 5.879"
- Alternator pulley diameter: 2.0625"
- Pulley ratio: 2.8504
- Engine Idle: 580-675 RPM (observed on OBDCII) LNXPenguin's rig
- Alternator output seems to stabilize reliably above 750 RPM (at engine), 2,137.5 RPM (at alternator pulley) based on KingTruc's rig w/ 180A alternator
- Alternator may stabilize as low as 2000 RPM at alternator pulley, 700 RPM (at engine) based on LNXPenguin's rig w/ 270A alternator
- Based on observations, a 1 25/32" diameter alternator pulley, creates a 3.30:1 ratio, this should get 650 RPM at engine to 2145 RPM at alternator, theoretically fixing the problem.
Suggested corrective actions applied:
- Got rid of cheesy stock battery clamps and charging cables.
- Upgraded alternator output cable to 1/0 with 5/16" lug at alternator B+ output, to 300A ANL fuse holder, to 5/16" lug to fastening bolt of marine style terminal.
- Upgraded battery ground cable from 4AWG to 1/0 with 5/16" lug at engine block. Cable was fed through the stock hall current sensor, and terminated 3/8" lug to military style terminal on negative post.
- Odyssey Extreme Series 34R-PC1500 KingTruc
- Odyssey Extreme Series 34R-PC1500 LNXPenguin
|I installed two 4ga cables (less than 2 ft each and going from alternator to battery positive and battery negative to engine) yesterday and the voltage fluctuations are still present. It's present primarily at idle and other RPMs when the engine is not under load. Engine idle speed once warmed up is 600-700 RPM. I used a multimeter connected to the front 12v outlet for readings.|
|Yesterday, on the freeway drive home after the install and going 65-70 MPH with engine RPMs between 2,000-2,250, voltage mostly held at 14.88v for the 30 minute drive home. In-town, city driving, voltages were between 14.4-14.6v but never hitting or going above 14.7v.|
|This morning when starting the car in about 55 degree (F), voltage was at 15.1v and held. In-town, city driving voltage ranged but held between 14.4-14.85v for a 10 minute trip. Two 15-minute trips on the freeway afterward saw steady voltage rise and mostly hold between 14.75-14.88v. Returning to in-town, city driving afterward, voltage was between 14.4-14.63v but never hitting 14.7v. 14.63v was only if driving was sustained without stops for at least 1/2-3/4 of a mile.|
| I think I've solved the voltage fluctuation mystery I've been dealing with but the rest of the voltage scenarios are still the same. The alternator I have doesn't like the stock 650 RPM idle. I connected my Bully Dog to check the idle reading and voltage (which is even more jumpy than my multimeter and down by ~0.1-0.2v from the multimeter). As soon as I increase idle speed to 750 and above, the voltage stabilizes and doesn't dip down to ~13.8v but stays in the 14.4-14.7v range depending on where the X is in the warmup cycle (lower after warmup).|
|I adjusted the idle yesterday using the Bully Dog to between 760-800 RPM for the time-being to test and it's been stable, which leads me to believe that DC Power is using the incorrect idle RPM spec to build the alternator in addition to whatever else is going on with this alternator.|
|On secondary and afterward trips in city driving, it's still not hitting 14.7v. On sections that exceed 1/2-3/4 mile or on the freeway, it does get up into the 14.6-14.8+v range.|
|I'm going on a camping/wheeling trip for the next few days so we'll see how it behaves on the trail. I don't want to keep my idle at 750-800 RPM, which is 15-20% above stock, just to resolve this alternator issue.|
|DC Power sent a replacement alternator. I swapped the alternators and the replacement alternator is exhibiting the same voltage fluctuations at idle. I also replaced the serpentine belt (Continental 4070873) and belt tensioner (Gates 38378) after the alternator swap and no change.|
|Update: after 300 miles today, voltage set point appears to have settled at 14.4-14.5 volts. Idle bobble is reducing a good deal too, it's looking like 13.9-14.4 which is a smaller window. I did experience one glitch in my audio system when the voltage jumped to 15.3v shortly after cold start and driving on city streets. Screen blacked out completely for 2 seconds. Everything came back with no noticeable adverse effects.|
|I headed out toward corral hollow today, and encountered snow just outside of Murphys, CA. Looks like they got a good dusting the past few days. I drove through snow and turned around just past Dorrington, traffic got a bit nasty. In 34 degree weather, the lowest voltage output i saw was 14.2v at 2500 rpm. Once i got to warmer temps at slightly lower elevation and no snow, 14.5 was seen at 1000rpm+. I am a bit concerned that the set point seems to have drifted that much in a day. On the drive home at freeway speeds, holding 2200-2500 rpm, i saw brief bursts of 14.8, but 14.5 was typical. I feel comfortable with the battery being fed 14.5 constantly and i think this new alternator is going to work out great. |
|I never saw voltages like what I get now with my stock alternator, even brand new. I had always complained to Nissan that the stock alternator was barely pushing out an acceptable voltage, but they kept saying as long as it hits at least 13.6v at times, the charging system is working properly, I think the highest I ever saw was 14.2 and that was only for a minute or 2 after startup. As months passed and the warranty crept up on expiration, I kept seeing voltages sink lower and lower. I was upset when I would only see 12.4v on the meter, this was definitely not charging the Odyssey battery anywhere near full. I had to plug in the expensive Odyssey charger after long trips to keep the battery happy. The 12.4 got my attention, so I rolled the dice and upgraded the alternator. Overall, I have to say I am pretty happy. It looks like I broke the unit in pretty well yesterday and the voltages are beginning to settle. I hope to see the bobble at idle go away soon. |
|Quote: Originally Posted by PhullD View Post|
|I can take a video if you like. Mine has been doing this since I was able to monitor it via the Bully Dog. It bounces back and forth a bit (14.2V-14.6V) depending on temperature. When fully warmed up it can be anywhere from 13.9-14.6V, usually 14.2-14.4V. Probably normal, I wouldn't think much of it.|
|It's good to know that the voltage variation at idle seems to be normal even stock. I have a simple volt meter that reads directly from the battery and that is what I based my readings on. The meter on my HAM radio is connected straight to the positive terminal on the battery and to the ground lug on the engine block where the hall current sensor connects. There is a 0.1-0.2 variance between the voltages at certain times. I was really surprised to see how quickly temperature affected the output voltages as well. One day is hardly enough data to give an accurate overall impression and I am just throwing out things as I observe them. I hope to get a better how to set up as it seems there is mild interest in it.|
|I went to go test out the rig in the snow. The ammeter didn't show up until late so I haven't gotten it connected yet. I have 2 meters here that I am going to test out, here are links:|
|The top one uses a hall effect sensor similar to the one built into the X, the second one requires a shunt to be installed. I probably won't have time until the weekend to try this install. If I get to it sooner, I will definitely post results. The first link, I tested on my radio and I am not getting accurate readings, but the manufacturer is saying it won't properly report loads less than 30A, my radio takes 5.68A at peak so I hope it will work on the X. The second is a amp/volt/watt/coulomb and capacity meter. It has a pretty beefy shunt and will hopefully handle the sustained current through it. I am a bit worried about overheating since it is a large potential current running in. I have noticed my idle voltages have really settled in today, at the long stop lights here, the fluctuations have tightened up from 13.9-14.2v. I think that this is an acceptable variance and could just be meter error at that point. I am still waiting to hear back from Steve at RR. The battery has charged up to the full 12.9v and shows that with engine off. |
|With the stock alternator, I was getting lucky if the engine off voltage was 12.1-12.4, which was very low in my opinion. When it would get to the 12.1v range, I knew it was critical to get the Odyssey charger out there. It sucked having to let the rig sit in the driveway plugged in for 10-14 hours. Now, when I shut off the engine, the voltage holds at 13.0 for about 20 minutes and eventually settles in at 12.8-12.9, which is more in line with the tech specs for an Odyssey. Now the battery achieves the accepted "fully charged" level shown in the Odyssey manual, meaning anything over 12.65v is fully charged and ready to go. I am curious too as to how the voltage fluctuations ironed themselves out. Perhaps the 2 120 mile freeway speed stretches helped break in the alternator or something. It's all speculation without being able to see the actual amperage vs voltage being produced. |
|I drove 450 miles Sunday, went to Yosemite with friends. Left at 5am, got home about 9pm, this was the first time I drove in the dark since I installed the new alternator. The voltages are still holding stable at idle within 0.3-0.5v BUT I notice the head lights ramping up and down in intensity in sync with the odometer back light. It has to be annoying for the driver I am behind to have the lights ramping up and down in brightness. It is really noticeable the darker it is outside. I need to figure out what is causing this now. I am going to try adding another lug from the engine block to the chassis, not that goofy lug that goes to the sensor module bracket.|
|Edit: I noticed even new, the rig had issues with lighting at idle with the stock off-road lights on. They would change in intensity. Dealership said this was normal as at idle, alternator isn't generating as much power. It wasn't a big deal then. Looking at some pictures of other people's rigs, there appears to be a grounding point near the coolant reservoir, under the stock battery location judging by the picture. There is nothing there for my rig. I will try running a ground strap from the engine to the chassis at or near that point.|
|Followed this thread for install:|
|How-to: Alternator Replacement - 2005+ VQ40DE *CPL*|
|And noticed lack of ground lug based on GeoXplorer's thread: How-to: Dual Battery Install - Under the Hood *CPL* (pic 10)|
|I really am beginning to wonder if the lug that Dave shows was a deletion between the Off-Road becoming the Pro-4x model. It seems there were funny deletions between model years. The stock negative cable only connected to the Voltage sensor bracket, but all surfaces including threaded portion appeared powder coated, and then a branch to the engine block. Going out on a limb, I wonder if this is why the fluctuation problem seems to be common to 2 2011+ models.|
|I will do some "field" testing and post results. |
The smaller diameter of the RR pulley introduces a bit more belt slack and nearly maxes out the tensioner's ability to pull in the slack, after much deliberation, I think the unanimous decision is to use this belt 5070862
for the GT-R!
**Apologies to the mods for all the edits. Just didn't want to lose any of the information. I combed 23 pages to distill it into a more digestable format. **
Please, for the love of God, people chime in and help us solve this problem. Remember, "Only you can prevent forest fires." That's not the one.
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|___________ This is what I was looking for.
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