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Discussion Starter · #1 · (Edited)
Having just gone through the RVC problems I make reference to a earlier 2011 post on how a properly functioning Cruze system should perform, particular to the post by n4435rc :

http://www.cruzetalk.com/forum/17-o...uze-regulates-voltage-boost-fuel-economy.html

In 2011 there appeared a rash of RVC problems noted on this forum. Then the reported occurrences appeared to die out until recently when its seems that the last 1-2 years another rash of RVC problems are potentially appearing. I make the connection that RVC problems are showing up symptomatically as widely varying DIC voltage ( 11.1 to 15.5 volts), random dead batteries (I had this happen to me), early (premature-under 3 years failures) factory battery replacement. I would make the argument that the advent of RVC systems has brought a host of new problems which did not exist with the old "dumb" charging systems although the origins can be vary basic in nature once the system is understood and analyzed.

For the last 6 months and 15K miles and one occurrence of a dead battery for no reason, I watched while my DIC voltage display vary from 11.1 volts to 15.4 volts with the only explanation that it was a "smart" charging system. Understanding the basics involved for charging a battery one quickly concludes that the dismissal of this "PROBLEM" as "SMART" charging is just simply B.S. and there is and was an underlying problem. I repeat this drama for the only reason, there are new Cruze drivers experiencing this problem and lessons learned some time ago have been forgotten. A battery life can be defined in the number of discharge/charge cycles to which a battery is subjected. So if a RVC system is malfunctioning it can subject a battery to MANY more cycles then it would otherwise be in normal operation. If the battery is not maintained at 85% charge due to faulty RVC system, the battery charge can be sitting at a level just charged enough to start the car but if the car is left unused for extended periods the parasitic currents drain the battery so that level of charge is no longer enough to start the car. A battery maintain at a low level of charge will have a shortened life span. It has been reported (service bulletin issued) that the neg battery cable has a defective crimp which causes a low charge/no start condition. Therefore there is an on underlying on going problem unless repaired/replaced properly and completely. This condition can extend into any of the high current charge and starter cable crimp lugs including that 3" jumper cable between the battery positive post and the fuse block top of the battery.

Well in my case the solution was simple... it was not only the neg battery cable with the defective crimped lug it is basically ANY of the high current large gauge cables which can have this lug crimp problem! After pulling out each battery cable one by one, examining the results to see incremental improvement with each repair made to the cables. Ultimately one needs to remove the cables, stake the lugs to the wire, drill the lug and solder each lug through the drilled hole to make a good low resistance contact with the wire. If one had a Milli-ohm meter one could measure each cable to determine if repairs are required. However in my case brute force of repairing all cables proved wise in that after the job was completed the RVC functioned as described. The DIC voltage display now no longer wanders any lower then 12.8 volts and no higher then 15.0 volts. One can even see the change in charging voltage as the temperature transitions through 32 F, it actually now functions was as designed!!

So if you are having any of the titled problems, have your RVC system thoroughly checked out to insure it functions as designed.:grin:
 
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I will have to watch my volts to see what's going on with them. My factory battery only lasted 2.5 years and there's no doubt a reason.
 

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My RVC runs from 11.5 to 15.5 volts and I'm still on the factory battery, four years and 80K miles. While RVC may be a stresser on batteries, it is not the cause of early battery death. JD Powers has reported that the battery is the number one item replace in the first three years of a new car's life; even more than tires.
 

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For whatever the reason battery life has declined.

Blame poorer quality batteries, higher electrical demand or global warming - batteries are just not lasting as long as they used to.

I have twice gotten more than 10 years out of a side terminal Delco - and just 2.5 years out of the one in my CTD. But as we know, Delco is no longer Delco.
 

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Discussion Starter · #5 ·
I believe we all have to admit that RVC is the common NEW addition to the charging systems over the last several years but also occurring at a similar pace as application of RVC is the decline in the battery warranty period offer by the manufacturers. Is this just Coincidence or are the battery manufacturers recognizing the inherent potential for real problems with RVC?:uhh:

There were just to many crimp issues on my Cruze's battery cables and non functioning RVC to blame any issues solely on the battery at this point. The battery needs to be charged properly to expect at least the min life from it! The posted material by n4435rc in 2011 clearly indicates that the battery voltage should not drop below 12.8 V if the VRC is working properly. A voltage of 11.2 volts is clearly a high discharge state for the battery. After the simple repairs to the all battery cable lugs my battery voltage no longer drops below 12.7V and i hope the problem was caught before the battery was damaged. Although the battery does have one total discharge state on it from the cut off not working (another defect??).
 

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I watched mine on a drive this morning. it held pretty steady at 14.6-14.7 but I didn't drive very far. Just long enough to warm up the oil for a change.
 

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I believe we all have to admit that RVC is the common NEW addition to the charging systems over the last several years but also occurring at a similar pace as application of RVC is the decline in the battery warranty period offer by the manufacturers. Is this just Coincidence or are the battery manufacturers recognizing the inherent potential for real problems with RVC?:uhh:

There were just to many crimp issues on my Cruze's battery cables and non functioning RVC to blame any issues solely on the battery at this point. The battery needs to be charged properly to expect at least the min life from it! The posted material by n4435rc in 2011 clearly indicates that the battery voltage should not drop below 12.8 V if the VRC is working properly. A voltage of 11.2 volts is clearly a high discharge state for the battery. After the simple repairs to the all battery cable lugs my battery voltage no longer drops below 12.7V and i hope the problem was caught before the battery was damaged. Although the battery does have one total discharge state on it from the cut off not working (another defect??).
Did you replace the alternator, or just the faulty cables? If just the cables then this isn't an alternator issue. It's the alternator that's variable output. Bad cables can occur even with a traditional single output alternator.
 

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In all this discussion, something else should be remembered: The DIC is just one voltage measurement of the system and may not represent the actual voltage on the battery. It might be reading low because of resistance between the battery and the voltage measurement. But why is it being allowed to be so low (since it appears the voltage measurement is being made at the same point as the system voltage is regulated)? First, there's a limit as to how much the alternator can go. Second, the system also has a battery current sensor. If charge current is too high, the voltage will be dropped until the charge current falls within spec. So the system may not be undercharging batteries, but boiling them.
 

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Discussion Starter · #9 · (Edited)
I watched mine on a drive this morning. it held pretty steady at 14.6-14.7 but I didn't drive very far. Just long enough to warm up the oil for a change.
.

Watch your DIC voltage (and your driving:grin:) from when the car starts through warm up to hwy driving when battery charge has reached full float state and battery temp stabilizes, if your RVC (smart charging) is functioning one will see the state/conditions as described in n4435rc write up from 2011. Once stabilized and warmed up one should clearly see voltage decrease as you accelerate (un-loading) and increase (regen) when you slow down. Also as temperature transitions down through 32 F you will see the voltage increase. Those are the easy to spot activities of RVC.

Did you replace the alternator, or just the faulty cables? If just the cables then this isn't an alternator issue. It's the alternator that's variable output. Bad cables can occur even with a traditional single output alternator.
No reason to replace a good alternator! Only the cable lug crimps were found defective with low parasitic resistance. All high current cable lugs were re-staked, drilled, and soldered with 96/4 silver solder, that was the only fix!

The main pos battery cable (artery from top of battery fuse block to starter to alternator) was replaced with 2 awg in consideration that OEM cable is only 4 awg and the high CCA required for cranking a cold diesel at -37 F with oil that has 5K miles and full of soot not to mention degraded oil temp stabilizers!!

In all this discussion, something else should be remembered: The DIC is just one voltage measurement of the system and may not represent the actual voltage on the battery. It might be reading low because of resistance between the battery and the voltage measurement. But why is it being allowed to be so low (since it appears the voltage measurement is being made at the same point as the system voltage is regulated)? First, there's a limit as to how much the alternator can go. Second, the system also has a battery current sensor. If charge current is too high, the voltage will be dropped until the charge current falls within spec. So the system may not be undercharging batteries, but boiling them.
The DIC display voltage was check against a NIST traceable DVM connected right on the battery terminals and found to be within 0.1V of the DVM.

The Cruze alternator is able to meet full normal electrical demand of a warmed up engine at idle and produce >12.8V (no glow plugs or add on power amps, etc). My initial concern was that since the voltage would randomly vary (before the fix) between 11.1v and 15.4v there was concern for discharge (11.1v ) and overcharge (15.4v)

One needs to remember that the Cruze has a "smart" charging system ( RVC) therefore the system voltage will vary from around 12.8V and about 15.1v based on many conditions including regen when slowing down and unloading when accelerating. Well... that is when its not suffering from a dumbed up disability due small parasitic resistance in defective high current cable lug crimps. In the older "dumb" charging systems one would never have notice the small parasitic resistance.
 

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The DIC display voltage was check against a NIST traceable DVM connected right on the battery terminals and found to be within 0.1V of the DVM.
As I recall, the measurement is done at the BCM. And I wasn't questioning the accuracy of the measurement, but that it's taken, though the wiring harness, at a distance from the battery. I don't recall any dedicated voltage measurement leads. Hypothetically speaking, any current though defective voltage measurement leads is going to throw off the voltage measurement. As long as the voltage measurement is being taken though wiring that is not dedicated to the voltage measurement (like a pair of test leads), there is a possibility that the voltage measured is not an accurate indicator of the battery voltage.

You stated "Even that short 3" jumper from the Pos battery terminal to the fuse panel contributed to the problem. " I don't think that wire has anything to do with charging, but could well be part of the voltage measurement process.


We also can't ignore the current sensor on the battery. It's not there for grins and giggles. It also must be playing a part in determining system voltage. I'd imagine that the BCM is going to limit the system voltage to limit the charging current on the battery. If the measured current is erroneously low, then the system will command an high voltage - limited only by the limit of what it can command and the battery current. That would cause an overcharge, rather than an undercharge.

You stated "Even that short 3" jumper from the Pos battery terminal to the fuse panel contributed to the problem. " I don't think that wire has anything to do with charging, but could well be part of the voltage measurement process.

Clearly, a wiring problem is the root cause, but until we know exactly what parts, I'd like to keep an open mind on what exactly is happening.
 

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One needs to remember that the Cruze has a "smart" charging system ( RVC) therefore the system voltage will vary from around 12.8V and about 15.1v based on many conditions including regen when slowing down and unloading when accelerating. Well... that is when its not suffering from a dumbed up disability due small parasitic resistance in defective high current cable lug crimps. In the older "dumb" charging systems one would never have notice the small parasitic resistance.
So the problem isn't the smart charging system. It's the cheap cables paired with it. You just invalidated your premise that RVCs are responsible for shortened battery life. It's been well known in the electrical engineering community for decades that crappy cables will lead to early replacement of almost all electrical components.

What you have identified, however, is a possible cause of early battery death in the Cruze - bad cables. Since GM already knows the main Negative battery is bad in some vehicles maybe this cable should also be replaced when a battery dies under the B2B warranty.
 

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This is an interesting concern... I own a 2015 with 40000 kms on it and log every PID that is available on Torque Pro, including Voltage (Control Module) and voltage (OBD Adapter) and decided to review the last two commutes which for this day a drive on the old coastal highway with lots of short hills and speeds between 50 and 100 KPM. The first is before sunrise and includes an engine shutdown key in run while I stopped for coffee and the second is mid day. The very last column has the delta between Control and OBD voltages

I am concerned about the initial battery voltage and the voltage decay in run mode, engine off (sort of indicates the size of the load when the alternator is not running. I provided the complete log for both runs in my Dropbox for your review and discussion, a sample is logged every 500 milliseconds

https://www.dropbox.com/s/ap7gvnz0fep24zu/trackLog-2016-Mar-04_04-48-55 latlong cleaned.csv?dl=0

https://www.dropbox.com/s/4sehp2czd8vyt92/trackLog-2016-Mar-04_11-06-04 latlong cleaned.csv?dl=0
 

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I watched my battery voltage on a longer trip today and I saw between 13.9 and 14.8
 

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Discussion Starter · #15 · (Edited)
So the problem isn't the smart charging system. It's the cheap cables paired with it. You just invalidated your premise that RVCs are responsible for shortened battery life.
Your argument is faulted!! Look at it as a "complete" system which has to work together in a real automotive environment and not in a perfect isolated world on it own!!

Suppose the head lights, radio, ignition system, HVAC system, body control system, etc, etc,etc quit working just because there was a few milli-volts difference in the 12V battery supply or "glitches"? I believe everyone would consider that ridiculous!! But this is the real world environment for any vehicle, train locomotive, and airplane, etc! There can be significant variations in these environments due to electrical surges/transients, temperature, humidity, etc, etc. Suppose your car quit working just because its humid outside? The system needs be fault tolerant and still function correctly. And these same engineers are putting driver less vehicles on our highways? I think I'll go back to walking!! LOL

Chances are the RVC was design in a lab using hand made cables and not production cables made by the lowest bidder, by children in a third world country so you could have your Cruze for less then $50,000 and the Auto Industry CEO's could keep their "Golden" parachutes!!

Another example of designed for the auto environment, the 6.0L PS diesel FICM requires 48V to open and close an injector for each injection cycle. The 48V DC to DC converter operates from a nominal 14.0V with the engine running. However it will continue to convert 10.5V to 48V which is a lower voltage then any 6.0L PS will turn over at. That lower voltage could be due to a ohmic contact, connection, etc but it did not matter because the system FICM continued to function!! I make the same argument for RVC it needs to function in REAL WORLD AUTOMOTIVE environments that is its application NOT setting in someones constant AC line voltage control environment living room.

Clearly the Cruze RVC is not a 6 sigma design where a few milli ohms due to cheap cable crimps can cause its dysfunction, dumbing up, no start, low voltage, and contribute to short battery life through erratic charging. Do you truely believe that the few remaining battery manufactures all conspired to provide cramp batteries to the auto industry and shorten their warranties deliberately? Or maybe it was the realization that there are problems with the "whole" RVC system and like systems by any other name, so they are just playing CYA because they don't want to take the fall and become the stuckee?
 

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Discussion Starter · #16 ·

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Discussion Starter · #17 · (Edited)
I watched my battery voltage on a longer trip today and I saw between 13.9 and 14.8
That observation is typical after the system stabilizes but does not reflect start up conditions before stabilization occurs. My DIC voltage, after repairs, will "float" at a constant 13.8 to 13.9v after stabilization (charge cycle) and constant speed. If I was to decelerate the voltage will go up (regen) or if I was to accelerate the voltage would go down (unloading the engine). This process of regen/unloading is claimed to save all of 8 miles per tank of fuel or about 1.5% is the claim. Don't use it all on one trip.:eek:ccasion14:
 

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I believe we all have to admit that RVC is the common NEW addition to the charging systems over the last several years but also occurring at a similar pace as application of RVC is the decline in the battery warranty period offer by the manufacturers. Is this just Coincidence or are the battery manufacturers recognizing the inherent potential for real problems with RVC?:uhh:

There were just to many crimp issues on my Cruze's battery cables and non functioning RVC to blame any issues solely on the battery at this point. The battery needs to be charged properly to expect at least the min life from it! The posted material by n4435rc in 2011 clearly indicates that the battery voltage should not drop below 12.8 V if the VRC is working properly. A voltage of 11.2 volts is clearly a high discharge state for the battery. After the simple repairs to the all battery cable lugs my battery voltage no longer drops below 12.7V and i hope the problem was caught before the battery was damaged. Although the battery does have one total discharge state on it from the cut off not working (another defect??).
Having just gone through the RVC problems I make reference to a earlier 2011 post on how a properly functioning Cruze system should perform, particular to the post by n4435rc :

http://www.cruzetalk.com/forum/17-o...uze-regulates-voltage-boost-fuel-economy.html

In 2011 there appeared a rash of RVC problems noted on this forum. Then the reported occurrences appeared to die out until recently when its seems that the last 1-2 years another rash of RVC problems are potentially appearing. I make the connection that RVC problems are showing up symptomatically as widely varying DIC voltage ( 11.1 to 15.5 volts), random dead batteries (I had this happen to me), early (premature-under 3 years failures) factory battery replacement. I would make the argument that the advent of RVC systems has brought a host of new problems which did not exist with the old "dumb" charging systems although the origins can be vary basic in nature once the system is understood and analyzed.

For the last 6 months and 15K miles and one occurrence of a dead battery for no reason, I watched while my DIC voltage display vary from 11.1 volts to 15.4 volts with the only explanation that it was a "smart" charging system. Understanding the basics involved for charging a battery one quickly concludes that the dismissal of this "PROBLEM" as "SMART" charging is just simply B.S. and there is and was an underlying problem. I repeat this drama for the only reason, there are new Cruze drivers experiencing this problem and lessons learned some time ago have been forgotten. A battery life can be defined in the number of discharge/charge cycles to which a battery is subjected. So if a RVC system is malfunctioning it can subject a battery to MANY more cycles then it would otherwise be in normal operation. If the battery is not maintained at 85% charge due to faulty RVC system, the battery charge can be sitting at a level just charged enough to start the car but if the car is left unused for extended periods the parasitic currents drain the battery so that level of charge is no longer enough to start the car. A battery maintain at a low level of charge will have a shortened life span. It has been reported (service bulletin issued) that the neg battery cable has a defective crimp which causes a low charge/no start condition. Therefore there is an on underlying on going problem unless repaired/replaced properly and completely. This condition can extend into any of the high current charge and starter cable crimp lugs including that 3" jumper cable between the battery positive post and the fuse block top of the battery.

Well in my case the solution was simple... it was not only the neg battery cable with the defective crimped lug it is basically ANY of the high current large gauge cables which can have this lug crimp problem! After pulling out each battery cable one by one, examining the results to see incremental improvement with each repair made to the cables. Ultimately one needs to remove the cables, stake the lugs to the wire, drill the lug and solder each lug through the drilled hole to make a good low resistance contact with the wire. If one had a Milli-ohm meter one could measure each cable to determine if repairs are required. However in my case brute force of repairing all cables proved wise in that after the job was completed the RVC functioned as described. The DIC voltage display now no longer wanders any lower then 12.8 volts and no higher then 15.0 volts. One can even see the change in charging voltage as the temperature transitions through 32 F, it actually now functions was as designed!!

So if you are having any of the titled problems, have your RVC system thoroughly checked out to insure it functions as designed.:grin:
So you are blaming the system as a whole for this problem when you posted that fixing the cabling errors fixed your car's problems. Then you claim that the system as a whole is faulty. In cars without bad wiring the RVC system works as designed. The final statement to check the RVC system is inaccurate - the accurate statement would be to check all the power cables in the engine bay. Based on your posts you did NOT check your alternator, just the cables.
 

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Discussion Starter · #19 · (Edited)
So you are blaming the system as a whole for this problem when you posted that fixing the cabling errors fixed your car's problems. Then you claim that the system as a whole is faulty. In cars without bad wiring the RVC system works as designed. The final statement to check the RVC system is inaccurate - the accurate statement would be to check all the power cables in the engine bay. Based on your posts you did NOT check your alternator, just the cables.
Yes I do blame the RVC system, you fail to grasp the concept that every other system from basic engine function of starting and running, lights , radio, HVAC all work properly with the cables lug as they were, EXCEPT the RVC system. That system was not design to work with REAL world component tolerance stacking, in simple engineering terms its NOT a 6 sigma design and it only works with perfect components in an engineering laboratory... otherwise one will see varied and UN-predicable results.

This is not a new issue isolated only to the Cruze, go to the other boards including the trucks and one will see a similar pattern developing with RVC and like system by any other name.
 

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That observation is typical after the system stabilizes but does not reflect start up conditions before stabilization occurs. My DIC voltage, after repairs, will "float" at a constant 13.8 to 13.9v after stabilization (charge cycle) and constant speed. If I was to decelerate the voltage will go up (regen) or if I was to accelerate the voltage would go down (unloading the engine). This process of regen/unloading is claimed to save all of 8 miles per tank of fuel or about 1.5% is the claim. Don't use it all on one trip.:eek:ccasion14:
OK, so I watched it from startup. It started out at like 11.7, went up into the 12's briefly, then back into the 11's briefly then it started climbing until it got into the 14's and from there remained in the high 13's to mid 14's.
 
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