Voltage Gage Always Showing 15V

[Rebel69]

Is 15V the normal reading for the '06 RAM 2500's? It seems to be high, but I can't vouch for the accuracy of the factory gages. I'm wondering if overvoltage is the reason that I'm having lamps burning out... first the headlights, then the rear parking lamps, the fog lights and now all of the lamps in the HVAC cluster.

 

[JHardwick]

14. 8vdc is considered stock volts.

 

[Rebel69]

I believe ya, but I'm wondering why Sylvania rates their SilverStar fog lamps to run at 12. 8 vdc, which would explain the high failure rate.

 

[DPellegrin]

I would recommend that you get a good quality volt-ohm-meter (VOM) like a Fluke or Simpson and check the voltage at the batteries while the engine is running with all accessories turned off and at least 10 minutes after you have started the engine.



The voltage regs in these vehicles are thermally compensatiing. For example in on a 70F day the stabilized voltage on my '96 and 01 is 13. 9 volts. This morning the ambient temp here was 15F and the stabilized voltage was 14. 3. Even when its -20F the highest voltage I have seen is 14. 6. BTW I have a calibrated digital voltmeter wired directly to the output terminal of the alternator. The readings I am quoting do not come from the dash meter, although it's pretty close.

I have never seen 14. 8V as a previous poster has indicated is standard, although this may be a new specification for 06's, However, I would think battery manufacturers would have a problem with this, 14. 8 volts would be hard on the battery.

 

[JHardwick]

I have never seen 14. 8V as a previous poster has indicated is standard, although this may be a new specification for 06's, However, I would think battery manufacturers would have a problem with this, 14. 8 volts would be hard on the battery.

Nope, your right, I was thinking 13. 8vdc, and stated 14. 8vdc ... ... ... ... ... ... been messing with the radio equipment too much lately where everybody likes to volt their transistors to 15vdc.

 

[LRundberget]

I would recommend that you get a good quality volt-ohm-meter (VOM) like a Fluke or Simpson and check the voltage at the batteries while the engine is running with all accessories turned off and at least 10 minutes after you have started the engine.

I would second that, but get a gauge permanently installed on the dash somewhere. The reason is that the volt gauge on these trucks are technically an idiot light in the form of a gauge so it appears more than a light. You can tell, when you start the truck that the gauge runs around 12 volts for awhile. Then all the sudden it jumps to 15 volts and stays there. But turn on your lights and you can see the headlights dimming when the grid heaters turn on again, but the gauge never fluctuates. The gauge is controlled by the EMC. A high tech idiot light is what we have in the cluster, not a true volt gauge.

 

[jelag]

DPellegrin is on the money...

Most modern circuits have an issue with poor grounds... if you get access to digital meter... place one end of the meter on the ground lug on the back of the alternator and the other lead on the negative terminal of the battery... . any... read this as any voltage read during this test is a voltage drop test and it should be ZERO with the batteries charging..... lets say for an example this reads . 2 or . 3 volts... this . 2-. 3 is voltage drop from a bad ground somewhere in the circuit and needs correction...

The same test can be run when the engine cranks to find bad connections in the starting circuit...

Hope this helps. .

 

[MegaCleanCab]

newb questions

I would second that, but get a gauge permanently installed on the dash somewhere. The reason is that the volt gauge on these trucks are technically an idiot light in the form of a gauge so it appears more than a light. You can tell, when you start the truck that the gauge runs around 12 volts for awhile. Then all the sudden it jumps to 15 volts and stays there. But turn on your lights and you can see the headlights dimming when the grid heaters turn on again, but the gauge never fluctuates. The gauge is controlled by the EMC. A high tech idiot light is what we have in the cluster, not a true volt gauge.

I get this voltage fluctuation during colds starts. Is this normal? My Gauge does move from 12-14 volts and the headlights dimm and brighten.

 

[CJ Johansson]

The old standby specs for 12V charging systems are:
13. 8V float charge (when the battery is pretty much charged)
14. 2V heavy charge (when batteries are down a bit)

Those probably aren't the "official" names, but it's pretty normal for 12V vehicle systems to run somewhere between 13. 8 & 14. 2 for a while after you start the engine and then taper off to around 13. 8V. These voltage points really have more to do with lead-acid battery chemistry than anything else.

These may not be what Dodge uses, but they should be pretty close. Most regulators compensate for temperature as well as the actual alternator current draw, so you may see slightly different voltages at times.

As for ratings on bulbs, one way bulb manufacturers get "super bright" bulbs is to run them hotter (make them for lower voltage). This comes at the cost of lower life span, but then they get to sell you more bulbs...

-cj

 

[steved]

They run more voltage when its cold... increased resistance, which the sensor allow more output from the alternator.

I'd put a volt meter on it, but you should be around 14. 5 volts... we forget that we need a "driving" voltage to charge the batteries.

Could also be as simple as the guage is off slightly...

steved

 

[rbattelle]

I get this voltage fluctuation during colds starts. Is this normal? My Gauge does move from 12-14 volts and the headlights dimm and brighten.

This is normal. It's the grid heaters drawing down the system voltage.

but get a gauge permanently installed on the dash somewhere. The reason is that the volt gauge on these trucks are technically an idiot light in the form of a gauge so it appears more than a light. You can tell, when you start the truck that the gauge runs around 12 volts for awhile. Then all the sudden it jumps to 15 volts and stays there. But turn on your lights and you can see the headlights dimming when the grid heaters turn on again, but the gauge never fluctuates. The gauge is controlled by the EMC. A high tech idiot light is what we have in the cluster, not a true volt gauge.

What you suggest is lame behavior is perfectly normal. As DPellegrin points out, the factory voltage gauge is accurate. On pre-2006 trucks they supressed the gauge movement during the postheat cycle to prevent people from thinking something is wrong (like MegaCleanCab did).



Ryan

 

[ENafziger]

For whatever it's worth, I have a digital volt meter connected through the 12v Accessory Power on the dash, and it reads consistently between 15. 1 - 15. 4 volts while driving.

--Eric

 

[DPellegrin]

For whatever it's worth, I have a digital volt meter connected through the 12v Accessory Power on the dash, and it reads consistently between 15. 1 - 15. 4 volts while driving.



--Eric

I think you need to get to the bottom of this problem. Maximum charging voltage, even when the ambient temperature are cold, and I mean cold, -20F here in MN this week, are 14. 6-14. 7. If 15. 1-15. 4 is accurate, this is definitely damaging your batteries!



Regards,