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just checked my battery voltage...in a short drive..it's 15.4..

is this normal..i thought ranges should be below 15 or are ranges higher now...

just curious what everyone else is finding for voltage readings...

thanx
 

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...14.7 Vdc is the "normal" re-charging voltage for a mildly dis-charged lead-acid battery (warm weather)

...that 15.4 Vdc reading is slightly high and is a possible indication that the alternator & voltage regulator are attempting to "re-charge" the battery after a large current load has been used, such as after a "cold" start. And, yes, voltage readings above 15 Vdc are not usually good (can burn-out lamps), but will often occur during COLD weather.

...a "no-load" voltage below 12.6 Vdc points to a battery that's either weak or not fully charged.
 

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Throw 1500watts RMS in your trunk and you won't be seeing that kind of voltage anymore, I was surprised these cars came with 120amp alts, but I'm happy, I won't be upgrading my alternator for my sound system.
 

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...there's also a 140 Amp alternator available, RPO: KG9 - Generator 140 A
 

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Charging Voltage........moves..

Around 2007 or so GM's charging system became more "intelligent" and monitors the battery and system loads closely. The system will vary the charging voltage to balance the load and battery state of charge. I really noticed this more so on our 2009 Silverado ( with the big voltage gage ). At times I'll see the voltage down around 12 volts (system broke!:eek:) or right up there around 14/<15 volts ( ah..,that's better:)). So, don't be alarmed...it is now the norm to see this voltage fluctuation.
 

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Batteries have a negative temperature coefficient that also varies with the battery manufacturer due to chemical differences. Charging voltage depending on the battery and temperature can vary anywhere from 12.9 to 15.5 volts.

The colder the temperature is, the higher the charging voltage as to be over a defined temperature range of -40 to 125*C.

If you applied 12.9 VDC to a battery at -40*C, would would not be charging it, would be discharging it instead. Worked closely with then the Delco battery division for setting up the desired temperature curve for the longest battery life. Since these curves change with aftermarket batteries, best to stick with the same battery your vehicle came with.

What you are seeing in your changing charging voltage is not only perfectly normal, but intended.

One of biggest mistakes made was mounting the voltage regulator inside of the alternator that also contains that temperature sensor, fooled by the extreme heat of the alternator for undercharging the battery. Delco battery division was screaming about that as their warranties went way up. We did add an external sensor for the CS-144 sensor, but was only used in higher end GM vehicles, added about 20 cents to the cost.

Not a problem for Delco anymore, we are history. Prices of our vehicles are skyrocketing, everything inside is made cheaper/ Toyota, Honda, etc. are no better in at least this one respect.

Don't blame engineers, we all know better, but had to comply or they would find somebody else.

Personally, I am happy to see 15.4V when the ambient temperature is -15*F.















v
 

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just checked my battery voltage...in a short drive..it's 15.4..

is this normal..i thought ranges should be below 15 or are ranges higher now...

just curious what everyone else is finding for voltage readings...

thanx
I checked mine the other day and it read the exact same voltage. 15.4 on the button. But battery voltage varies. 15.4 seemed a bit high to me, but that could be the characteristic of the Cruze. It was cold outside and the volts read higher in colder weather. Also, it does have a lot of electronics and it needs a lot of voltage to power them.
 

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My 1998 Buick Park Avenue shows on the DIC that the battery voltage is between 13.4-13.8 and never has shown higher. Out of curiosity one day I grabbed my Fluke meter and checked the voltage when the engine running on the battery, actual voltage on a calibrated meter was 14.6 and I checked the DIC at that time and it show 13.5. Remember that the gauge in the car can and often is inaccurate. My Cruze I did the same test and it was spot on with the Fluke meter. Automotive gauges and meters are and can off by a bit and not effect the car as the real readings can be a lot different. Just remember that the vendor that made the gauge or reader for the system has a certain range that are acceptable.

I always think that the automotive industry taught the government about the lowest bid. John Glenn was asked what he was thinking strapped into the space ship on the first orbital flight and he said all that he think about was that the rocket and space ship were made by the lowest bid.
 

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For years, the automotive industry used an ammeter in series with the battery, with low output generators, would show a discharge with the headlamps on and at idle. The actual load taken from the generator was not shown, but would show a positive charge to the battery if it was low. Once the battery was fully charged, this ammeter would go to zero.

Sound confusing it was, so finally the ammeter was dumped in favor of just showing the alternator output voltage. An expanded scale voltmeter was adopted to use a cheaper smaller meter, but a voltmeter is nothing more than an ammeter with a series resistor. That resistor can be calibrated to read accurately.

And for that matter, so can the oil pressure and temperature gauge refering to strictly analog gauges. For years, GM and other were cheating with the oil pressure gauge, just using a fixed resistor to a low pressure switch for oil pressure. As long as that switch was closed at 2.5 psi, oil pressure would show full, under 2.5psi, switch would open of zero oil pressure. Not much different than using an oil pressure lamp. Cruze is using the same cheap scheme, one reason to judge actual engine oil pressure is to install an accurate gauge.

Fuel gauges are far more complicated, rare to find a linear tank in automotive like rectangular, the resistance of the sender has to match the characteristics of the tank. This could be done with nichrome with the spacing between the wires to match the characteristics of the tank, but now they are using a very cheap conductive ink on a ceramic substrate. Average cost to produce a resistor of this type is like 3/4 of a cent. Also subject to erosion caused by ethanol based fuels.

Yet another factor is that the sender has to be mounted in the precise center of the tank, if forward or sideways, vehicle level plays a role what that sender will output.

With the Cruze, compensation is made by a single multiplexed A to D converter, where digital data is mapped to a lookup table for mean corrections. But definitely more accurate than pure analog for both the fuel tank and voltage displays.

Speedometers is yet another gauge, with the analog cable driven type had to change the strength of the magnetic field of a permanent magnet. this was tricky for calibration. Linearity is also a factor. Cruze uses a Vss that applies pulses to the PCM. With trucks could actually calibrate these yourself with different tires. How this is done with the Cruze, have yet to find out. Mine is darn accurate compared to the GPS readout. But suspect as the tires wear, will read lower. Ironically, I can purchase a 15 buck bicycle speedometer where I can easily set it to one part in 10,000. But can't do that with my Cruze. Maybe my dealer can do that with the generation III, haven't learned that yet.
 

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I checked mine the other day and it read the exact same voltage. 15.4 on the button. But battery voltage varies. 15.4 seemed a bit high to me, but that could be the characteristic of the Cruze. It was cold outside and the volts read higher in colder weather. Also, it does have a lot of electronics and it needs a lot of voltage to power them.
It is not the battery charge level that is being reported by the DIC. It is the charging system output that is being shown. That will vary according to the load put on it by the engine and everything else that uses electricity.
 

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