# RVC - battery volts, dead battery and early factory battery replace problems



## diesel (Jun 8, 2013)

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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## obermd (Mar 3, 2012)

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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## Tomko (Jun 1, 2013)

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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## theonlypheonix (Oct 8, 2015)

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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## diesel (Jun 8, 2013)

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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## obermd (Mar 3, 2012)

theonlypheonix said:


> 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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## ChevyGuy (Dec 13, 2014)

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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## theonlypheonix (Oct 8, 2015)

diesel said:


> 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.



obermd said:


> 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!!



ChevyGuy said:


> 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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## ChevyGuy (Dec 13, 2014)

theonlypheonix said:


> 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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## obermd (Mar 3, 2012)

theonlypheonix said:


> 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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## obermd (Mar 3, 2012)

I just created a poll at http://www.cruzetalk.com/forum/25-s...ent-replaced-your-negative-battery-cable.html to see what our members' experience has been.


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## ssnscruzeeco2015 (Dec 29, 2014)

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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## diesel (Jun 8, 2013)

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


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## theonlypheonix (Oct 8, 2015)

obermd said:


> 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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## theonlypheonix (Oct 8, 2015)

obermd said:


> I just created a poll at http://www.cruzetalk.com/forum/25-s...ent-replaced-your-negative-battery-cable.html to see what our members' experience has been.


All you need to do is sum up all the posts on this board covering like topics since before 2011 up to today's date, there are many.


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## theonlypheonix (Oct 8, 2015)

diesel said:


> 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.ccasion14:


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## obermd (Mar 3, 2012)

theonlypheonix said:


> 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??).





theonlypheonix said:


> 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
> 
> ...


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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## theonlypheonix (Oct 8, 2015)

obermd said:


> 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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## diesel (Jun 8, 2013)

theonlypheonix said:


> 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.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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## theonlypheonix (Oct 8, 2015)

After about 6 months of observations it seems that the major repairs required to stabilize the voltage range has been accomplished so that the nominal DIC displayed voltage no longer drops into the low 11's (11.1 to 11.2 v) . While the DIC voltage variations does appear quite active they're no longer are reaching the past lows of 11's V as was the common conditions prior to repairs. Some people look for simple one fault repairs but in many cases the problems can have their origins in multiple causes. While I'm not sure I am in agreement with some of the observed voltage vs external stimulations, the change in voltage can be correlated to the external stimulation of operating conditions. During all observations and repairs the alternator remained the original as the car was equipped from the factory.

Observations generally seen after engine start up are as follows, the voltage will quickly rise and run in the 13.8 to about 14.6 range until the battery charge state is reached, assuming one drives long enough to fully charge the battery. Also deceleration will tend to push the voltage up (regen) and acceleration will push the voltage down (unloading engine). Low temperatures will push the voltage up and high temperatures will push the voltage down. The HAVC system operation will generally push the voltage up also. A lot of these coordinated changes require observation over longer time periods at a steady speed. However some can be observed occurring quite rapidly i.e. the changes due to accel and decel allowing for the slow DIC display updating.

There are some note worthy events with the automatic headlight control. I saw no difference in voltage display when the headlights are manually turned on or off... however with the automatic light control on, when the automatic control turns the lights on the voltage would increase to the 13.8V to 14.5V range and when the automatic control turns the lights off the voltage could drop to a low of 12.5 V depending on battery charge state and Accel or Decel conditions, temperature, etc. Note the battery voltage is a true 3D mapping depending on the many active external operating inputs and state of battery charge, temperature, accel/decel, HVAC state. Under all normal loading conditions using standard equipped accessory's I could not get the voltage to drop below 12.6 V with a charged battery. Obviously if one was to equip their car with non standard equipment i.e. 2000W amp or power convertors the results would be much different. I've also put a glove over the light sensor so that the car runs with the headlights on, the DIC voltage will always be in the 13.8 to 14.4 V range. Its also worthy to note that after running in this state long enough to charge the battery to this new level, with the battery on a load tester the battery now shows a higher state of charge as one might expect.

So far I have not had a reoccurring event of dead battery after parking as happen when the car was 300 miles new. But I'm concerned over whether the On-Star system can check on the car operating state even with the ignition turned off? If On-Star can check the car with the ignition key off then they could leave the transmitter in an on state thereby draining the battery and therefore being the origin of the "dead battery" after the car has sat for a period of time. Does turning ignition key off disconnect On Star?


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## ChevyGuy (Dec 13, 2014)

theonlypheonix said:


> Does turning ignition key off disconnect On Star?


They wouldn't be able to unlock your car if it did.


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## theonlypheonix (Oct 8, 2015)

ChevyGuy said:


> They wouldn't be able to unlock your car if it did.


That's exactly my contention, the system is in hibernation mode until they need to pull information from it. Even though I'm not an OnStar subscribe I still get emails that I can get my cars latest diagnostic report. Which means they are remotely monitoring my cars operation even while it should be asleep with the ign key off and removed . So what happens if their monitoring software has a bug in it that after sending a report on diagnostic the transmitter is left in an on state while the car is setting at an airport for 7-10 days, it would follow that it would drain the battery. Seems that this could suggest the random "battery dead" issue when the cars are left key off for extended periods of time. Maybe its time to pull the fuse on OnStar if one doesn't use their service. What good is OnStar at a remote airport location with a dead battery? :uhh: I've had to resort to my cell phone service to call roadside assistance at 12:00 am in the morning for this common emergency situation. So can OnStar be summed up as a basic false sense of security?


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## ChevyGuy (Dec 13, 2014)

theonlypheonix said:


> So what happens if their monitoring software has a bug in it that after sending a report on diagnostic the transmitter is left in an on state while the car is setting at an airport for 7-10 days, it would follow that it would drain the battery.


You can say that about any module - of which the Cruze has at least a dozen. Just read a post today about someone claiming the blind spot monitoring system stayed on due to corrosion in the harness.


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