# Battery volts



## winterset (Jan 21, 2015)

My 2014 diesel has 29k & original owner, and today i scrolled thru the battery volts for the first time. It read 12.2 running. I thought that was very low. Usually a parked car reads 11.9 - 12.0, and all my GM cars read up to 14.6 when running. Is this normal, or is the battery or alternator on the brink of a failure / fault?


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## Cruzator (Dec 31, 2014)

Drive the car and coast down a hill. Voltage will go up past 14.5. It is controlled by the computer. Goes up under no engine load. Will go down with engine load and at idle.


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## Tomko (Jun 1, 2013)

This voltage reading does not alarm me for a CTD as you describe. 

If you ever see it below 12.0 then it's time to raise a flag.


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## BU54 (Nov 24, 2014)

Voltage is a nominal 13.2 with the engine off. Each battery has 6 cells and each cell produces roughly 2.2 volts. A good test would be to monitor your voltage with the headlights and other accessories on while driving. If the battery doesn't need a charge then the alternator will not produce current to the battery. This is how the regulator works so the battery isn't being charged when not needed hence increasing the battery life. Charging isn't bad for a battery but charging when it isn't needed is.


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## diesel (Jun 8, 2013)

I have similar numbers on mine.


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## pandrad61 (Jul 8, 2015)

the alternator output varies by load on engine.


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## Canadian Cruzer (Oct 27, 2014)

winterset said:


> My 2014 diesel has 29k & original owner, and today i scrolled thru the battery volts for the first time. It read 12.2 running. I thought that was very low. Usually a parked car reads 11.9 - 12.0, and all my GM cars read up to 14.6 when running. Is this normal, or is the battery or alternator on the brink of a failure / fault?


I see the same low reading on mine and would expect, like you, to see over 14v. Mine has been like this since day one and has not been a problem in the 1.5 years I've had it, so the reading must be wrong on our cars (guessing cpu glitch.).


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## Tomko (Jun 1, 2013)

No reading error. Just a very efficiently designed electrical system on the CTD. 

Remeber, this electrical system is not sustaining a high-voltage ignition system just to keep the engine running.


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## Cruzator (Dec 31, 2014)

This probably falls under TMI, but here it is for those that might be interested.









[h=3]2014 Chevrolet Cruze 2.0L Eng Diesel[/h]
[h=3]Charging System Operation[/h] The purpose of the charging system is to maintain the battery charge and vehicle loads. There are 6 modes of operation and they include:


Battery Sulfation Mode
Charge Mode
Fuel Economy Mode
Headlamp Mode
Start Up Mode
Voltage Reduction Mode
 The engine control module (ECM) controls the generator through the generator turn ON signal circuit. The ECM monitors the generator performance though the generator field duty cycle signal circuit. The signal is a pulse width modulation (PWM) signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is between 5-95 percent. Between 0-5 percent and 95-100 percent are for diagnostic purposes. The following table shows the commanded duty cycle and output voltage of the generator:

Commanded Duty CycleGenerator Output Voltage10%11 V20%11.56 V30%12.12 V40%12.68 V50%13.25 V60%13.81 V70%14.37 V80%14.94 V90%15.5 V
 The generator provides a feedback signal of the generator voltage output through the generator field duty cycle signal circuit to the ECM. This information is sent to the body control module (BCM). The signal is PWM signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is between 5-99 percent. Between 0-5 percent and 100 percent are for diagnostic purposes.
[h=3]Battery Sulfation Mode[/h] The BCM will enter this mode when the interpreted generator output voltage is less than 13.2 V for 45 minutes. When this condition exists the BCM will enter Charge Mode for 2-3 minutes. The BCM will then determine which mode to enter depending on voltage requirements.

[h=3]Charge Mode[/h] The BCM will enter Charge Mode when ever one of the following conditions are met.


The wipers are ON for more than 3 seconds.
GMLAN (Climate Control Voltage Boost Mode Request) is true, as sensed by the HVAC control head. High speed cooling fan, rear defogger and HVAC high speed blower operation can cause the BCM to enter the Charge Mode.
The estimated battery temperature is less than 0°C (32°F).
Battery State of Charge is less than 80 percent.
Vehicle speed is greater than 145 km/h (90 mph)
Current sensor fault exists.
System voltage was determined to be below 12.56 V
 When any one of these conditions is met, the system will set targeted generator output voltage to a charging voltage between 13.9-15.5 V, depending on the battery state of charge and estimated battery temperature.

[h=3]Fuel Economy Mode[/h] The BCM will enter Fuel Economy Mode when the estimated battery temperature is at least 0°C (32°F) but less than or equal to 80°C (176°F), the calculated battery current is less than 15 amperes and greater than -8 amperes and the battery state-of-charge is greater than or equal to 80 percent. Its targeted generator output voltage is the open circuit voltage of the battery and can be between 12.5-13.1 V. The BCM will exit this mode and enter Charge Mode when any of the conditions described above are present.

[h=3]Headlamp Mode[/h] The BCM will enter Headlamp Mode when ever the headlamps are ON (high or low beams). Voltage will be regulated between 13.9-14.5 V.

[h=3]Start Up Mode[/h] When the engine is started the BCM sets a targeted generator output voltage of 14.5 V for 30 seconds.

[h=3]Voltage Reduction Mode[/h] The BCM will enter Voltage Reduction Mode when the calculated ambient air temperature is above 0°C (32°F). The calculated battery current is less than 1 ampere and greater than -7 amperes and the generator field duty cycle is less than 99 percent. Its targeted generator output voltage is 12.9 V. The BCM will exit this mode once the criteria are met for Charge Mode.


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## James1549 (Sep 14, 2015)

Wow, I have worked with diesel engines all my life and never heard of these low readings as being normal. Something new to learn.

James


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## obermd (Mar 3, 2012)

Those of us with the gas trims had to learn the same things. The Cruze's alternator is variable output to save fuel. It only provides sufficient voltage to charge the battery based on actual loads.


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## boraz (Aug 29, 2013)

James1549 said:


> Wow, I have worked with diesel engines all my life and never heard of these low readings as being normal. Something new to learn.
> 
> James


its not a diesel thing, its fuel efficiency


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## ChevyGuy (Dec 13, 2014)

I think the simple takeaway is the Cruze is much more sophisticated than most cars. I believe most just pump out 13.8 - 14.4 and use "float charge" to charge the battery. The Cruze does much more. It a computer controlled charging system. It monitors the battery current and the needs of the car.

Note that a fully charged battery (minus the float charge) is only 12.6. So once everything is charged, it doesn't need to be more than that.


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## revjpeterson (Oct 2, 2013)

boraz said:


> its not a diesel thing, its fuel efficiency


Yeah. GM has actually been using this variable output alternator technology for quite a while, but it seems that it went unnoticed until recently. I became familiar with it because my 2007 Grand Prix already had this tech. So when I got my Cruze, I was already used to seeing those numbers and it just seemed normal.


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## Reno12469 (Sep 25, 2015)

Normal. When I worked out of my car and had it running all day during the summer it would stay around 12.8V to 13V. During the winter I'd be in and out of the car all day and would have the heated seats on and the fan on high to keep it hot inside. Would always be at 15.3V. I thought something was wrong because I didn't know they would charge that high. Kinda sucked because I needed to use an inverter to charge the laptop all day and it would kick out because it would only work up to 14.8V. I did have the battery fail on me after one winter though. Don't know if it was a bad battery or the load on it. Warranty replaced it.


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## James1549 (Sep 14, 2015)

obermd said:


> Those of us with the gas trims had to learn the same things. The Cruze's alternator is variable output to save fuel. It only provides sufficient voltage to charge the battery based on actual loads.


I drove my '14 2LT RS today for several hours, city and hiway. Never once did it go under 13.6 and above 14.4 during that time.

James


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## peobey (Aug 9, 2015)

Same design for the fuel pump. GM uses a FPCM that controls the voltage to the pump. This extends the life of the pump, regulate pressure on our returnless system and prevents vapor locks. Also helps with emissions.

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## diesel (Jun 8, 2013)

peobey said:


> Same design for the fuel pump. GM uses a FPCM that controls the voltage to the pump. This extends the life of the pump, regulate pressure on our returnless system and prevents vapor locks. Also helps with emissions.
> 
> Sent from my Nexus 4 using Tapatalk


diesels don't get vapor lock


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## peobey (Aug 9, 2015)

Oh well... Just re-read the thread and realised it's about a diesel. Fml

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## James1549 (Sep 14, 2015)

diesel said:


> diesels don't get vapor lock


I would think that vapor lock with a gas engine is a thing of the past with the pump in the tank.


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## peobey (Aug 9, 2015)

If the check valve is damaged, it's very well possible.

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## theonlypheonix (Oct 8, 2015)

Cruzator said:


> This probably falls under TMI, but here it is for those that might be interested.
> 
> 
> 
> ...


This is very interesting if this is really whats happening? I've been watching the volt indicator very closely since I found the battery "DEAD" after leaving the car parted at the airport for 1 week (note nothing was left turned on and the 2015 Cruze diesel was only 2 weeks old). What I've been seeing is the voltage vary from a low of 12V to a high of about 14.8. The other strange part was the more electrics you turned on or the higher the RPM the lower the voltage would go. This on the surface would be what one would normally expect with a defective alternator or a battery going bad. If it wasn't for the dead battery I might agree with above explanation as correct or in the alternative there is a "BUG" in their otherwise what might be call "a Smart" charging algorithm?? I still like the old charging method where a charged battery would be floated around 13.2 volts and last 7-9 years. Today the battery manufacturer will not warranty their battery's for more then 3 years which has changed from 7-9 years a few years ago. Is this the result of advancement in technology??? I don't think so!!


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## ChevyGuy (Dec 13, 2014)

Without knowing exactly where the voltage is being measured, I'm not sure how much I'd worry about it. The voltage at the ECM isn't the same as the voltage at the battery itself.


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## peobey (Aug 9, 2015)

ChevyGuy said:


> The voltage at the ECM isn't the same as the voltage at the battery itself.


I disagree. The voltage should be the same across the board aside from very minor millivolts variations due to all the connections/connectors which act like small parasitic resistance.

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## ChevyGuy (Dec 13, 2014)

peobey said:


> I disagree. The voltage should be the same across the board aside from very minor millivolts variations due to all the connections/connectors which act like small parasitic resistance.


At the current the higher loads draw, you can easily lose several tenths of a volt in places. 

Since the BCM directly supplies the current for all lights (except for high beam and fog), I can see the voltage dropping at the BCM when more lights are turned on.


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## peobey (Aug 9, 2015)

ChevyGuy said:


> At the current the higher loads draw, you can easily lose several tenths of a volt in places.


Yes, but voltage will balance out. Quickly. At the speed of light .



ChevyGuy said:


> Since the BCM directly supplies the current for all lights (except for high beam and fog), I can see the voltage dropping at the BCM when more lights are turned on.


The BCM might feed current to them but his power input wires are engineered for this. They have bigger wires which prevents voltage drops due to overheating. Even if it is under major loads, the voltage won't drop enough for you to get a different reading at the battery vs V+ @ BCM. Now the dashboard might say otherwise because it could be buffered. I remember when I worked at a GM dealership before I joined, when the GMT 900 series came out, people kept complaining that the truck wouldn't charge after a cold startup. It was true. The BCM had a charging strategy that consisted of waiting a few seconds after initial startup before charging. The voltmeter reflected that. People started calling in like crazy saying they bought a 60k truck that doesn't charge. We tried explaining them. I guess GM's CS reps got tired of repeating how it worked over and over. We had an ICM update quickly that buffered the voltmeter so that it wouldn't go all over the place. Calls/Visits stopped 


Edit: I can fix cars, but I can't HTML


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## ChevyGuy (Dec 13, 2014)

peobey said:


> Yes, but voltage will balance out. Quickly. At the speed of light .


Yes, but what "point" in the system is the one being regulated? The only one that really matters is the battery. Everything else is along for the ride. The voltage determines the charging current and becomes the charging strategy. A few tenths of a volt does make a difference here - but doesn't make a difference anywhere else. (Or at least shouldn't.)

The biggest question I have is if the DIC voltmeter is measuring the same point in the system as the one being regulated.

Yes, the wires are sized to not burn out or cause excessive voltage drop - but no more. Thicker wires add to the weight and the cost of the car - and makes no difference in the operation.


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## diesel (Jun 8, 2013)

theonlypheonix said:


> This is very interesting if this is really whats happening? I've been watching the volt indicator very closely since I found the battery "DEAD" after leaving the car parted at the airport for 1 week (note nothing was left turned on and the 2015 Cruze diesel was only 2 weeks old). What I've been seeing is the voltage vary from a low of 12V to a high of about 14.8. The other strange part was the more electrics you turned on or the higher the RPM the lower the voltage would go. This on the surface would be what one would normally expect with a defective alternator or a battery going bad. If it wasn't for the dead battery I might agree with above explanation as correct or in the alternative there is a "BUG" in their otherwise what might be call "a Smart" charging algorithm?? I still like the old charging method where a charged battery would be floated around 13.2 volts and last 7-9 years. Today the battery manufacturer will not warranty their battery's for more then 3 years which has changed from 7-9 years a few years ago. Is this the result of advancement in technology??? I don't think so!!


How long had your car sat on the dealer's lot before you bought it? How far was your drive to the airport? Some of these may factor in to a dead battery, but it's also likely the battery itself is bad. I have left my diesel sit for up to a week with never any battery issues.


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## theonlypheonix (Oct 8, 2015)

The car had 10 miles on it when I bought it about a month ago. When I parked it at the airport it had about 250 miles on the clock and today it has 1400 mi. I drive 60 hwy miles (60-70 mph) each way to and from work (enough time to charge even a dead battery). 

This past weekend although warmer temps the DIC voltage was all over the map (12 to 14.9 volts)again. Now this morning it was glued on 14.8 volts (note today it is 10 degrees cooler outside). Cruzator suggests that there are smarts behind battery charging which might explain what's going on but if its not a smart charging system then most likely there is an intermittent some where in the system.

I read about the service bulletin on the Cruze defective (-) battery cable and the issues with the ground terminals on the front left strut tower and front fender needing to be checked for proper torque from this site. However all that has been investigated and/or corrected yet there appears irregularities in the DIC voltage display. Can any one confirm as to whether there is a "smart" charging system as Cruzator states? I might have to connect a external volt meter directly to the battery to see whether it matches with the DIC display. Does anyone know for sure from what point the DIC taps off for its measurement?

Note that service said you have to drive 2 times a day or the battery will go dead from the static drain of ALL the electronics, I call BS on that!! Where do they find these service people?


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## obermd (Mar 3, 2012)

theonlypheonix said:


> The car had 10 miles on it when I bought it about a month ago. When I parked it at the airport it had about 250 miles on the clock and today it has 1400 mi. I drive 60 hwy miles (60-70 mph) each way to and from work (enough time to charge even a dead battery).
> 
> This past weekend although warmer temps the DIC voltage was all over the map (12 to 14.9 volts)again. Now this morning it was glued on 14.8 volts (note today it is 10 degrees cooler outside). Cruzator suggests that there are smarts behind battery charging which might explain what's going on but if its not a smart charging system then most likely there is an intermittent some where in the system.
> 
> ...


The Cruze does employ a load based alternator to improve fuel efficiency. Normal voltage readings are from 12.3/12.4 to 14.6. If your battery isn't staying charged when parked for a few days you most likely have a bad battery, which is covered under the B2B warranty. However, don't take it back to the idiots who told you the car has to be driven twice a day - I wouldn't let them change the AA batteries in my flashlight.


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## Kexlox (Nov 4, 2014)

theonlypheonix said:


> Note that service said you have to drive 2 times a day or the battery will go dead from the static drain of ALL the electronics, I call BS on that!! Where do they find these service people?


That's ridiculous. I've been working from home this last month, and my car sat for 3 weeks until this past weekend. It started up just fine.

In fact, the car has a drain protect mode, if you sit in the car with it on or using an accessory for too long, the car will start shutting things off to preserve enough charge to start the engine.


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## theonlypheonix (Oct 8, 2015)

It seems as though our cars are smarter then the service staff? Ok with that said I guess I will need to park the car again for a week and see whether the battery go's dead again. 

But what appears strange is that while driving at hwy speeds and normal electrical load turned on i.e. engine ECM, running lights, radio and HVAC fan on a setting of 3 or above the DIC voltage is indicating a steady state of about 14.7V (I would anticipate this). However keeping all things the same, turning the fan setting down to 2 or less or off (lowering the electrical load), within several seconds the DIC voltage indicator will begin to drop to a low of 12.1V to 12.2V where it will continue to hover around this level. My understanding is that a fully charged battery with no load will have a voltage indication of around 12.6V to 12.7V. A battery voltage of 12.1V is indicating a state of discharge especially when the alt should be keeping the battery in a charge state with a voltage of greater then 13 V. Now if I turn the fan speed back to a setting of 3 or greater (increasing the electrical load) the voltage will go back up to 14.7V. This why I believe there is a bug or threshold issue in their "smart" charging system. But then again I need to connect an external DVM directly to the battery since the DIC voltage might not be giving the true alt/battery voltage?


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## ChevyGuy (Dec 13, 2014)

theonlypheonix said:


> But then again I need to connect an external DVM directly to the battery since the DIC voltage might not be giving the true alt/battery voltage?


That's what I'd suggest. If the battery voltage is really over 12.6 or so, then it's just a display issue. If it really is dropping, there's a problem.


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## obermd (Mar 3, 2012)

theonlypheonix said:


> It seems as though our cars are smarter then the service staff? Ok with that said I guess I will need to park the car again for a week and see whether the battery go's dead again.
> 
> But what appears strange is that while driving at hwy speeds and normal electrical load turned on i.e. engine ECM, running lights, radio and HVAC fan on a setting of 3 or above the DIC voltage is indicating a steady state of about 14.7V (I would anticipate this). However keeping all things the same, turning the fan setting down to 2 or less or off (lowering the electrical load), within several seconds the DIC voltage indicator will begin to drop to a low of 12.1V to 12.2V where it will continue to hover around this level. My understanding is that a fully charged battery with no load will have a voltage indication of around 12.6V to 12.7V. A battery voltage of 12.1V is indicating a state of discharge especially when the alt should be keeping the battery in a charge state with a voltage of greater then 13 V. Now if I turn the fan speed back to a setting of 3 or greater (increasing the electrical load) the voltage will go back up to 14.7V. This why I believe there is a bug or threshold issue in their "smart" charging system. But then again I need to connect an external DVM directly to the battery since the DIC voltage might not be giving the true alt/battery voltage?


Since you're the first person to report this (that I know of) this isn't a bug in the system. I do agree that you have a problem with you alternator, but I really think it's more likely a faulty battery. Even at full blower with A/C on my ECO MT voltage will vary with the terrain - going up hill it's lower; down hill it's higher. The fact that you're seeing 14.7 V and then 12.1/2 V is indicative that their is either a problem with your car's charging system or, more likely in my opinion, a problem with the battery. The reason I'm leaning towards the battery is because we have had several reported early (as in < 6 months) battery deaths here. A bad cell in the battery will cause just this type of readings.


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## theonlypheonix (Oct 8, 2015)

obermd said:


> Since you're the first person to report this (that I know of) this isn't a bug in the system. I do agree that you have a problem with you alternator, but I really think it's more likely a faulty battery. Even at full blower with A/C on my ECO MT voltage will vary with the terrain - going up hill it's lower; down hill it's higher. The fact that you're seeing 14.7 V and then 12.1/2 V is indicative that their is either a problem with your car's charging system or, more likely in my opinion, a problem with the battery. The reason I'm leaning towards the battery is because we have had several reported early (as in < 6 months) battery deaths here. A bad cell in the battery will cause just this type of readings.


Every day I have a 60 mi drive to and from work with other then the radio to break up the boredom of the 1 hr drive. So to entertain myself I fiddle with the knobs especially when the battery goes dead for no appearance reason. Then for a profession I'm a test engineer which devises test plans to validate electronic products meeting their electrical specifications. So the first time the battery went dead I tried using the cars accessories to simulate different loading conditions on the alt/battery. The HVAC fan, head lights are the largest electric consuming devices. The fan is nice because it can represent a variable test load depending on speed setting.

Since the majority of my drive is at 65 MPH the engine rpm is constant at about 1900 rpm. At this rpm the alt should be able to reach its max capacity about 160 amps if the load demands but the test conditions don't demand full capacity. Going up and down hills is irreverent since cruise control is on keeping speed/ rpm constant. During the hour trip I have the DIC displaying voltage constantly so any deviations can be noted at the time it occurs. The only correlation with voltage fluctuations are not speed nor going up/down hills but load correlated through varing the fan speed in increments. It has been previously stated that the alt voltage is computer managed based on some algorithm. Years ago the regulator was very basic simple control, voltage drop due to increased load the regulator increase output to maintain battery charged state. Other then for starting the car the battery is just along for the ride while the alt does the real work for maintaining constant voltage as the electrical system load changes. The battery has been put on load tester and shown to be in better then average condition. So this leaves the alt to be misbehaving either due to a "smart" charging algorithm which has a BUG or an ohmic / intermittent electrical connection some where in the system. Cruzator appears to have some insight into the "smart" charging this system uses. The common Cruze ground terminals problem on the left strut tower, front left fender and under the air box have all be checked for corrosion and torqued. The defective (-) battery cable has been replace pursuant to the service bulletin noted on this blog in another post.

I would ask how many owners specifically constantly display their DIC voltage keeping the RPM constant while observing any variation in DIC voltage as the electrical loading is manually manipulated through the cars electrical accessories loading being changed?? It would be interesting to see whether other diesel owners conducting similar experiments would observe the same results??


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## ChevyGuy (Dec 13, 2014)

theonlypheonix said:


> It has been previously stated that the alt voltage is computer managed based on some algorithm. Years ago the regulator was very basic simple control, voltage drop due to increased load the regulator increase output to maintain battery charged state.


Depending on the gain in the feedback system, the voltage variation could be infinitesimal.

However, once you add a computer to the system with unknown programming ..... 

What I've been able to find out is that it appears the voltage sensing is done by the BCM, and the BCM outputs a PWM signal to the alternator. For starts, we have no idea if that PWM is "stepped" or continuously variable. I'll take a WAG that it's stepped though 256 different values based on a calculated 8-bit number.

But if you've got a scope handy, you might want to look for the ripple coming out of the alternator. The alternator is a 3-phase AC device, with diode packs to rectify it to DC. If one of the 6 diodes open up, you're running on "2 phase and a gap" which could cause some interesting system response and readings.


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## spacedout (Dec 7, 2010)

Kexlox said:


> That's ridiculous. I've been working from home this last month, and my car sat for 3 weeks until this past weekend. It started up just fine.
> 
> In fact, the car has a drain protect mode, if you sit in the car with it on or using an accessory for too long, the car will start shutting things off to preserve enough charge to start the engine.


I agree that statement is ridiculous, however the battery run down protection will not prevent long term storage battery drain. My understanding this system only monitors the cars lighting and possibly power points and turns things off after 10 minutes. 

Parking your car for more than 2 weeks your suppose to disconnect the battery to ensure the battery will have enough charge to start. 

How long can I park my car?


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## BU54 (Nov 24, 2014)

I've parked my '66 chevelle over the winter(4 months or so)and she fires up in the spring without charge, but I usually charge it first. Yes there's a big difference between then an now with electronics in vehicles and that what I'm hinting at. I've parked my '13 cruze for 3+ weeks and she starts without troubles.
Look how many problems the are with cars these days.
Years ago it was other than oil, filters and lube the front end every 3,000 miles.
1. Change the plugs/points every 1-2 years, and they were easy to change. I can change the 8 plugs in my '66 chevelle 3x in the time it takes to change the 6 plugs in my 2003 S-10 once.
2. Brakes, tires, battery and maybe shocks every +/-5 years.
3. Anti-freeze every 2 years.
4. That's about it folks!!


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## KpaxFAQ (Sep 1, 2013)

BU54 said:


> I've parked my '66 chevelle over the winter(4 months or so)and she fires up in the spring without charge, but I usually charge it first. Yes there's a big difference between then an now with electronics in vehicles and that what I'm hinting at. I've parked my '13 cruze for 3+ weeks and she starts without troubles.
> Look how many problems the are with cars these days.
> Years ago it was other than oil, filters and lube the front end every 3,000 miles.
> 1. Change the plugs/points every 1-2 years, and they were easy to change. I can change the 8 plugs in my '66 chevelle 3x in the time it takes to change the 6 plugs in my 2003 S-10 once.
> ...


On the other side of that coin, today's vehicles can go the entire lifetime of the vehicle without doing hardly any of that. Most people never change a plug period. Most people don't touch anti-freeze ever. The only people I know that change that stuff are people like us which is far from common! 

I'm not recommending any of that and probably over-maintain my stuff a bit but I guess I'm saying it's flat out amazing how long a modern vehicle can be abused with many times little repercussions. **** even super lax oil changes will easily get you well past 100k miles with the exceptions in certain motors. Your 66 Chevelle will let you know quick if you ignore any of that maintenance!

I'd take a modern vehicle from a reliability standpoint over something built in the 60's anyday. Not the cruze diesel but a normal naturally aspirated gasser with an automatic transmission. They definitely aren't as cool though!


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## obermd (Mar 3, 2012)

theonlypheonix said:


> I would ask how many owners specifically constantly display their DIC voltage keeping the RPM constant while observing any variation in DIC voltage as the electrical loading is manually manipulated through the cars electrical accessories loading being changed?? It would be interesting to see whether other diesel owners conducting similar experiments would observe the same results??


I have monitored my voltage over time while running on Cruze control. In hilly terrain at 65 - 75 MPH (interstate driving) my voltage goes up and down in response to the terrain. Voltage drops going up hill and climbs while descending. In all cases it stays between 12.3 and 14.6 volts however. I've done this with the A/C going with blowers on high and with A/C and blower off. I would have expected the voltage levels to stabilize over time while driving. Engine temperature (I have the digital readout) follows the same pattern, which I understand.


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## BU54 (Nov 24, 2014)

KpaxFAQ said:


> On the other side of that coin, today's vehicles can go the entire lifetime of the vehicle without doing hardly any of that. Most people never change a plug period. Most people don't touch anti-freeze ever. The only people I know that change that stuff are people like us which is far from common!
> 
> I'm not recommending any of that and probably over-maintain my stuff a bit but I guess I'm saying it's flat out amazing how long a modern vehicle can be abused with many times little repercussions. **** even super lax oil changes will easily get you well past 100k miles with the exceptions in certain motors. Your 66 Chevelle will let you know quick if you ignore any of that maintenance!
> 
> I'd take a modern vehicle from a reliability standpoint over something built in the 60's anyday. Not the cruze diesel but a normal naturally aspirated gasser with an automatic transmission. They definitely aren't as cool though!


Brake, tires and batteries are a wash, obviously. But look at how many problems there are with sensors and computers in vehicles these days, not to mention the associated costs for repair.
Back then one could perform 95% of this maintenance yourself.
Yes all this $$$ technology is impressive with MPG and HP per cubic inch. But I still love a car that one can diagnose and repair yourself. If GM or any other automotive company offered a car without all this computerized crap they have these days I'd but it in a heartbeat. The price tag would be at least 5k less. I can buy a lot of plugs and condensers for that kind of $$$. But the EPA will never let that happen.

Just think, if you had an older car and upgraded just a few things, like plugs, antifreeze, a pointless HEI distributor(like I did on my chevelle)but not all the other $$$ yuppie crap like continuous MPG and when to change your oil % reading and remote tire pressure, and the list goes on. Then there's all the emission crap and air bag$.

Curb weight for my chevelle with a 454 is 3800lbs. For my '13 cruze with a 4 banger it's 3200lbs.


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## Kexlox (Nov 4, 2014)

BU54 said:


> Curb weight for my chevelle with a 454 is 3800lbs. For my '13 cruze with a 4 banger it's 3200lbs.


I'll take the extra weight in safety, thanks!


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## BU54 (Nov 24, 2014)

Kexlox said:


> I'll take the extra weight in safety, thanks!


Many need it.

I'll take additional safety with careful driving, by not texting or talking on the phone. Along with being observant of the many others that do. Also not driving like it's a NASCAR race helps a lot too.
It's worked well for me for a very long time. If it's not broke don't fix it.


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## pandrad61 (Jul 8, 2015)

If i where making cars i would blend old and new school. If the epa would not but in we could make cars very fast,reliable, and safe by means of axing the complexity of emissions systems and that could be used to simplifying the performance and reliability of the car while upping mpg.


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## theonlypheonix (Oct 8, 2015)

obermd said:


> I have monitored my voltage over time while running on Cruze control. In hilly terrain at 65 - 75 MPH (interstate driving) my voltage goes up and down in response to the terrain. Voltage drops going up hill and climbs while descending. In all cases it stays between 12.3 and 14.6 volts however. I've done this with the A/C going with blowers on high and with A/C and blower off. I would have expected the voltage levels to stabilize over time while driving. Engine temperature (I have the digital readout) follows the same pattern, which I understand.


Here are typical charge no load voltages depending on battery technology:


State of Charge
Sealed or Flooded Lead Acid
Gel battery
AGM battery
100%
12.70+
12.85+
12.80+
75%
12.40
12.65
12.60
50%
12.20
12.35
12.30
25%
12.00
12.00
12.00
0%
11.80
11.80
11.80


from:
Battery voltage and state of charge - Energy Matters

So if the DIC voltage is lower then 12.80+ (my batt is a AGM Techno) it is being discharged when the DIC reads 12.0 to 12.8 assuming DIC is reading true system (battery) voltage. Its interesting that today during the same hwy drive the DIC voltage ranged from a potential discharge @ 12.0V to potential overcharge at 15.0V. Note I still need to connect an external DVM to confirm DIC software (BUG) is reading actual voltage or instead some made-up imaginary number!

I still maintain that going up or down a grade should make NO difference in battery voltage holding a constant RPM unless there is a grade sensor built in to adjust the voltage intentionally depending on grade, makes NO sense. I would call this a "BUG" also!

But maybe the intent is to extend battery life with intentional discharge cycles? However note recently battery warrenties have been shortened from 7-9 years several years ago to recently now ony 3 years. Who's kinding who !!

As a point of reference note that my F350 with dual batt and dual alts (max comb current 270 amps) holds 14.2 V from when the engine kicks off and the glow plugs are out. After that a constant 14.1 to 14.8V no matter what the load going up or down a grade, idle or hwy spds or outside temp. The AGM battery's are now 6 years old and still cranks the 6.0L diesel a -10 F without a block heater but then again its a FORD product?


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## obermd (Mar 3, 2012)

theonlypheonix said:


> I still maintain that going up or down a grade should make NO difference in battery voltage holding a constant RPM unless there is a grade sensor built in to adjust the voltage intentionally depending on grade, makes NO sense. I would call this a "BUG" also!


The Cruze uses a load based alternator. When there's more load on the electrical system the alternator works harder and you see a higher voltage. When there's less load and the battery doesn't need charging you'll see the actual battery voltage. For intermediate loads and battery charge levels you'll see an intermediate voltage.

I agree with you that going up and down hills shouldn't make a difference in voltage unless the overall engine load is also a contributing factor to how hard the alternator works - possibly high engine load lowers alternator output when the battery doesn't absolutely need charging to reduce the impact of the double whammy of uphill and engine load on overall fuel economy.


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## ChevyGuy (Dec 13, 2014)

theonlypheonix said:


> I still maintain that going up or down a grade should make NO difference in battery voltage holding a constant RPM unless there is a grade sensor built in to adjust the voltage intentionally depending on grade, makes NO sense. I would call this a "BUG" also!


Which way is it changing? The computer might decide to scale back the charging current to divert more power to the wheels when climbing a hill.

Still, I don't expect the car to ever go into discharge territory (12.7 or less) as long as the car is running normally.

I'm also assuming you don't have any add-ons that connect directly to the battery, possibly bypassing the current sensor and confusing the computer.


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## Cruzator (Dec 31, 2014)

I believe the Cruze also varies the voltage to maximize fuel economy. When you let off the accelerator, the voltage goes up. When under a load, the voltage goes down. There is also a change in the charging strategy based on temperature, and electric load on the system. I commonly see 12.2 volts while pulling a hill in the daytime (no lights or wipers on). Coasting up to a stop light, it will increase to 13.8 volts or higher. When it's very cold out, I've seen as high as 15.1 volts. This is all inline with what the repair manual says.


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## theonlypheonix (Oct 8, 2015)

theonlypheonix said:


> Here are typical charge no load voltages depending on battery technology:
> 
> 
> State of ChargeSealed or Flooded Lead AcidGel batteryAGM battery100%12.70+12.85+12.80+75%12.4012.6512.6050%12.2012.3512.3025%12.0012.0012.000%11.8011.8011.80
> ...


AH HA... finally nailed it or "staked" it as the case maybe!! One can make all the excuses they want but simply put the Cruze has a bunch of F' d up cable lug crimps!!

After watching for 15K miles the DIC display a voltage randomly any where from 11.1v (can you say discharge:uhh to 15.4v (overcharge:uhh the problem finally cured.:eusa_clap: Through repairing the defective crimped lugs and replacing a main cable this on going problem with the Cruze can be fixed once and for all.:grin: I believe I can now identify all the modes that the so called smart charging system go's through as described earlier in this thread. Once the original problem is repaired the DIC started to behave normal with a charge state now between 13.8v and 14.6v as one would expect with a properly functioning charging system, no more 11.1v and no more 15.4v. The voltage now hangs in there with load/no load almost as good as my F350 with dual group 65 batteries and dual alternators(OEM). :grin:

Solution... ALL large gauge battery cables lugs (pos and neg) were re-staked, drilled and soldered with 96/4 silver solder(do NOT used plumber solder or acid flux). Gremlins gone, Cruze has now been through full exorcism of the DIC voltage display! :grin:


My solution also included a big battery cable for the Cruze main artery (from the fuse block on top of battery, to starter, to alternator, 2 awg high strand count welding cable with all lugs staked and soldered with 96/4 silver solder and insulated with heat shrink):








It no wonder the batteries are going bad after only two years of operation!


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## ChevyGuy (Dec 13, 2014)

theonlypheonix said:


> AH HA... finally nailed it!! One can make all the excuses they want but simply put the Cruze has a bunch of F' d up cable lug crimps!!


Nice job! Now, if we can figure out just which cable is a fault instead of going though the whole batch.

I believe diesel uses a different battery, so it might use a few different cables. Certainly the one going to the alternator is going to be different. The ones different from the gasser would be the ones I'd start with.


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## theonlypheonix (Oct 8, 2015)

ChevyGuy said:


> Nice job! Now, if we can figure out just which cable is a fault instead of going though the whole batch.
> 
> I believe diesel uses a different battery, so it might use a few different cables. Certainly the one going to the alternator is going to be different. The ones different from the gasser would be the ones I'd start with.


Unfortunately it is not just "one", it is all contributing in small amounts to the over all problem. As I went thru each one I noticed a small improvement until all were done! Even that short 3" jumper from the Pos battery terminal to the fuse panel contributed to the problem. With the nice weather last Sat I spent the day puling them all out one by one until the problem was FIXED! (Note the cable in the above photo is my own home made replacement cable).

In my area of the country it can get cold and I wanted all CCA I could get to the starter so I up graded the main cable from #4 to #2. I may wait to see if my original battery has been damaged by all the discharge/charge cycling that was happening, but next plans are to attempt to shoe horn in a group 27F X2 (re-branded Northstar) battery.


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## carbon02 (Feb 25, 2011)

I've been troubleshooting the factory charging of the battery in my 1.4L. I remember finding a website with an article talking about the patent that General Motors had on alternator charging modes, that was rolled out with the Cruze. 

They were commanding a higher charge voltage when engine load was lower, or specifically the article mentioned deceleration. I believe this is in an attempt to charge the battery when the customer won't notice the "loss in Engine performance" when the alternator kicks in. 

Recently in the 1.4L, the battery was load tested and fully charged, but the car felt the need to charge at 15.1 Volts due to the outdoor temperature, and what it thought was needed. The car noticeably drove differently. What a load. After installing a battery tender on the battery connected in the car for 48 hours, finally the car realized the status of charge was ok, and the charging voltage came back down to where I've seen it historically. 

This article on google mentioned that the first car to get this alternator control strategy was the Cruze. I'm guessing the Diesel has the same type of code, and that's why your seeing volts increase under lower loads. Going downhill.

The advantage of the diesel, is that it probably has enough extra HP, where it doesn't feel so gutless with the alternator at higher charging .


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## theonlypheonix (Oct 8, 2015)

I thought we all were up to speed on this smart charging technology?

Are You Smarter than a â€˜Smartâ€™ Charging System? - Diagnostic News
Chevy Cruze uses patented Regulated Voltage Control technology - Torque News
http://www.devicemag.com/2011/03/29/chevrolet-cruze-rvc-technology-to-boost-fuel-economy/
http://www.greencarcongress.com/2011/03/cruze-20110328.html
http://www.gminsidenews.com/forums/f39/chevrolet-cruze-rvc-technology-boost-fuel-economy-101713/
http://www.autoblog.com/2011/04/02/chevy-cruze-regulates-voltage-to-boost-fuel-economy/
http://www.cruzetalk.com/forum/17-o...uze-regulates-voltage-boost-fuel-economy.html
http://diagnosticnews.com/wp-content/uploads/smart-charge-3.jpg


One of the problems with the "smart" charging is that it is very sensitive to stray "parasitic" resistance especially where it doesn't belong. One finds the "smart" regulator attempting to make corrections for conditions which really don't exist. Its just not smart enough to know the difference between a defect and an actual change in conditions. Sometimes the old KISS principle is better... unless one starts with a 6 sigma design, made with perfect parts in a country with manufacturing control processes in place. 

Yes, I'm referring to the basic cables that are in use and a problem on the Cruze.


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## obermd (Mar 3, 2012)

The alternator doesn't put that much load on the system that your typical driver will notice. What it does do, however, is require slightly more HP to turn it, which means more fuel gets consumed. The variable output alternator is used to reduce fuel consumption.


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