Voltage fluctuation

[Black_Pearl]

I have a new 19 ram (non-etorque). Typically, the voltage gauge reads about halfway all the time. A few times though I’ve noticed it jump from Half up one notch on the gauge and back down to half repeatedly, every few seconds. Idle, driving a short distance.. it doesn’t matter. The first time it did it, I drove about 8 miles with it happening and it stopped and didn’t do it the next few times I drove it. The other day, it did it again. It seems to correspond to times I don’t drive it for days or a week or more at a time. I don’t drive it that often. Maybe it’s normal and something to do with recharging the battery after extended idle periods. Has anyone else noticed this?
The owners manually actual mentions fluctuations can be normal but should eventually regulate it self out. I forget exactly what it says is happening, but it is mentioned.

 

[Zeronet]

I have noticed that after a cold start the voltage quickly rises to 14.5-14.6. Stays there for an hour or so. Doesn’t seem to matter if idling, highway, towing, shut engine off/turn on again. It seems to stay at that voltage for a while.

After that first hour though the voltage seems to settle to 14.1-14.2 and stay there the remainder of the day.

 

[Black_Pearl]

I have noticed that after a cold start the voltage quickly rises to 14.5-14.6. Stays there for an hour or so. Doesn’t seem to matter if idling, highway, towing, shut engine off/turn on again. It seems to stay at that voltage for a while.

After that first hour though the voltage seems to settle to 14.1-14.2 and stay there the remainder of the day.

I only have the basic tradesman gauges, all I know is halfway and a continuous jump every few seconds to the notch directly above it and back to halfway. Again, I think it corresponds with not having been driven in weeks. Im going to try testing my theory and driving it more often. It it doesn’t do it when driving it often, I’m going to equate it to bringing the battery back up to charge and just mention it to the shop.

 

[Fatherof3]

I think you can toggle through the evic to see the digital readout and see if it coincides with the gauge . Then you’d know if it’s just the gauge or the charging system itself .

 

[Willwork4truck]

I only have the basic tradesman gauges, all I know is halfway and a continuous jump every few seconds to the notch directly above it and back to halfway. Again, I think it corresponds with not having been driven in weeks. Im going to try testing my theory and driving it more often. It it doesn’t do it when driving it often, I’m going to equate it to bringing the battery back up to charge and just mention it to the shop.

If not driving for weeks better use a trickle charger or 1x a week overnight charge for battery health. Unless its parked someplace without any possible power.
There are small (10-15 watt) solar panels that can be suction cup mounted to the roof and the wires/clamps go down to the battery.

 

[Black_Pearl]

I’ll try the digital readout and make a conscious effort to drive it every day or so around town. I looked at my manual and don’t fine the reference I saw before, but instead found a reference to voltage fluctuations on the 2019 classic manual. Mine is not a classic. It says :

NOTE: The voltmeter may show a gauge fluctuation at various engine temperatures. This cycling operation is caused by the post-heat cycle of the intake manifold heater system. The number of cycles and the length of the cycling operation is controlled by the engine control module. Post- heat operation can run for several minutes, and then the electrical system and voltmeter needle will stabilize.

 

[securityguy]

My Uniden R7 has the option to also show battery voltage so I activated that feature. The voltage shown on my R7 is always identical to that on my gauge cluster so now I can constantly monitor my battery voltage while looking at other data on my dash. I typically run between 13.9V - 14.2V based on circumstance. I honestly don't believe you would need a charger unless it sat for a month or more.

 

[Black_Pearl]

So I’ve checked the digital readout and it’s running from 14.8 to 14.9v. The fluctuation is back and forth between those two numbers. Temperature outside is about 40 degrees. Is 14.9 too high?

 

[securityguy]

So I’ve checked the digital readout and it’s running from 14.8 to 14.9v. The fluctuation is back and forth between those two numbers. Temperature outside is about 40 degrees. Is 14.9 too high?

Sounds awfully high to me.

 

[Black_Pearl]

To be clear that is 40 degrees outside at cold start with nothing extra on but the radio. If I turn on the heat or air, the voltage goes down to 14.7 and sometimes 14.6. I even see a .1 v drop when I use the brakes too. So driving at 14.7 and hit the brakes it drops to 14.6 for a second.

 

[Black_Pearl]

I also should mention the truck and battery are brand new. Less than 600 miles on the truck. Battery was replaced before I took possession a month ago.

 

[Black_Pearl]

So I think the reason for the higher voltage is that the alternator is trying to charge the battery back up. I checked voltage with ignition on ACC today only and it was only 10 volts. Any ideas?

 

[Richard320]

So I think the reason for the higher voltage is that the alternator is trying to charge the battery back up. I checked voltage with ignition on ACC today only and it was only 10 volts. Any ideas?

That's way too low. 10V is even a little low during cranking, especially with a new battery. Unless you had a whole bunch of high-load things on, like seat heaters and rear window defrost. I'm going to assume you shut off as much as you could.

You have a bad battery or you have something draining the battery or you're not recharging the battery no matter what the voltmeter says. What you see on the dash when it's running is what is coming out of the alternator. That doesn't mean any of it is getting into the battery. Loose connections or corrosion somewhere could be all it takes. Or some module somewhere that should be powering down within two minutes of ignition off might be staying on and draining it.

 

[Black_Pearl]

When running, it reads 14.8 v. It’s odd. It starts fine. Then I let it warm up (idle maybe 10 minutes) and turned it back to just ACC and it said 12.6 v but started dropping by .1 v every 10 or 15 seconds.

 

[Black_Pearl]

What should it read in ACC mode?

 

[Richard320]

What should it read in ACC mode?

I would expect to see no less than 12.0V, provided you have shut off everything you can shut off. That includes blowers, defrosters, seat heaters, running lights, interior lights, radio.....

With everything off, testing the battery voltage underhood at the terminals it should be about 12.6 after sitting a few minutes to let everything power down. I wouldn't get real excited if it was a little lower because some modules take a long time to go to sleep.

 

[Black_Pearl]

Okay, so I drove around the truck for about half an hour today because, like I said, it hasn’t been driven much. Afterward, I checked the voltage at the battery and it was 12.68v off and 14.6v running. The voltage on the dash, while running matched at 14.6, which is lower than it has been. I guess the battery was depleted somewhat and it was pumping a higher voltage to charge it up. The ACC mode still said 10 v on the dash with just the radio running. Not sure what that is all about.

 

[RamCares]

Okay, so I drove around the truck for about half an hour today because, like I said, it hasn’t been driven much. Afterward, I checked the voltage at the battery and it was 12.68v off and 14.6v running. The voltage on the dash, while running matched at 14.6, which is lower than it has been. I guess the battery was depleted somewhat and it was pumping a higher voltage to charge it up. The ACC mode still said 10 v on the dash with just the radio running. Not sure what that is all about.

Hi Black_Pearl, we see that you have received some great advice from your fellow forum members! However, if these suggestions do not address your concern and you decide to visit your dealer, our team would be happy to offer additional assistance throughout that process. We are available via private message!

Rob
Ram Cares

 

[securityguy]

Hey guys, something I have noticed since the temps in FL have been getting hotter over the last few weeks. In the Winter, I noticed that my VOLTAGE during driving would be between 13.9-14.3V. Checking at the battery would be 12.3-12.4V after the truck has been sitting for a week without use.

Now that it is hot, once again, here in FL, I am seeing the following:

1. My voltage while driving is now between 13.6-13.9V
2. After sitting for a week, the voltage is now around 12.6-12.7V

Therefore, my conclusion is that your voltage will fluctuate with temperature. Not understanding all of the idiosyncrasies of the ET system, I just thought some may find this interesting

 

[RAM Patriot]

Hey guys, something I have noticed since the temps in FL have been getting hotter over the last few weeks. In the Winter, I noticed that my VOLTAGE during driving would be between 13.9-14.3V. Checking at the battery would be 12.3-12.4V after the truck has been sitting for a week without use.

Now that it is hot, once again, here in FL, I am seeing the following:

1. My voltage while driving is now between 13.6-13.9V
2. After sitting for a week, the voltage is now around 12.6-12.7V

Therefore, my conclusion is that your voltage will fluctuate with temperature. Not understanding all of the idiosyncrasies of the ET system, I just thought some may find this interesting

Voltage is directly proportional to resistant (V=IR) and resistance increases with temperature due to increased vibrations of the molecules inside the conductor. Therefore voltage increases as temperature increases.