Fridge/voltage question

[Markt1993]

I Have a 2021 Cherokee Grey Wolf. I have the voltage meter under the fridge that shows the battery voltage. When unplugged and I turn the battery switch on when coming out of storage it’s usually around 12.5ish. Once I tow it a ways it’ll usually be back up to around 13-13.5 volts.
All which I feel is about normal.
So I’ve had the camper about a year now and always noticed that when plugged up at any campground the voltage will mostly stay right about 13.5, but occasionally will go up as high as 14.1 or down to around 12.9-13, but will only stay a minute or so and level back around 13.5 again. I’ve never though much about it.
At the beach yesterday and the 12v Everchill fridge stopped working. Opened the door and the temp setting light was blinking. Quick google search said that always mean the voltage was too low and it couldn’t properly operate. I noticed yesterday morning the amp meter was showing 12.0-12.1.
So question is; how stable should the volts remain will being plugged in to power? I do know that the fridge only runs on 12v so the inverter is involved, is that the draw or problem? did the campground have an issue will low power at the box (AC was running all day, no notable problems), do I have a fridge problem, battery problem? And the fix was removing the fuse for about 2 hours and then starting it back up. Came back on and seems normal now. Just wondering if it was a fluke thing?
30 amp camper, even wondering if we are overloading it, but maybe not enough to trip a breaker. Between the AC, fridge, the kids scooters charging, golf cart plugged in? On top of that the 15amp plug at the box doesn’t work. Which I what I usually use to charge the golf cart and toys.
Thanks for any thoughts or advice

[Bama Rambler]

When you're on shore power the DC voltage should stay fairly stable, but will fluctuate depending on the state of the battery(s). It can run lower if the battery is drawing power during the charge cycle. Also if your battery has a bad cell or cells it can draw a lot of power from the converter/charger causing the system voltage to drop some.

Did you happen to notice what the 120v system voltage was when the 12v system was reading 12.0v? The shore power voltage could have been low enough to affect the converter current.

Also FYI, your 12 volt fridge doesn't use an inverter It has a 12 volt compressor, so it runs directly from the battery and/or converter.

[Markt1993]

Originally Posted by Bama Rambler

When you're on shore power the DC voltage should stay fairly stable, but will fluctuate depending on the state of the battery(s). It can run lower if the battery is drawing power during the charge cycle. Also if your battery has a bad cell or cells it can draw a lot of power from the converter/charger causing the system voltage to drop some.

Did you happen to notice what the 120v system voltage was when the 12v system was reading 12.0v? The shore power voltage could have been low enough to affect the converter current.

Also FYI, your 12 volt fridge doesn't use an inverter It has a 12 volt compressor, so it runs directly from the battery and/or converter.

I didn’t. We’d been on the beach, came back in and went to grab a drink and saw the light blinking. I removed the rear cover in the freezer and the fins were dry and room temp. I’d thought maybe with the high humidity it might have froze up.

Yea, I get what you mean about the battery. I’ve always felt a little fluctuation was fine. Today it’s stayed right on 13.5.

Seems that it was not a fridge issue but more of a low power issue. Would the AC still run fine? That was the one thing I was trying to figure out.

At that point the volts showed 13.5 again.

I’m wondering (if this is even possible) if the voltage was too low and basically the fridge was running on battery only and it got to low and it shut off?

I appreciate the help!

[ESGWheel]

The theoretical max per cell of a lead acid battery is ~ 2.1 volts. Thus 2.1V x 6 cells = 12.6VDC. Typically, the RV convertor that powers the 12VDC side of things is a ‘smart’ convertor > it has various states it toggles thru (boost, normal, storage and equalization) depending on what it senses the battery voltage to be and time. Each state has its own output voltage, as high as 14.1VDC. Thus, what you are seeing when on shore power is that voltage, not the battery independently. And when hooked up to your tow vehicle, same thing: the RV is getting its DC power from your vehicle’s alternator. The point being that the DC voltage can very by a few volts and that is normal and your systems can handle that. But your convertor does have it limits. I suspect that the DC side was overloaded and thus the DC voltage dropped to the point where your refer tripped offline to protect itself.

This would not have impacted your Air Conditioner as it runs on the 110VAC shore power. However, it is also sensitive to low voltage. I have seen RV campgrounds go as low as 85VAC (normal is 110 – 120VAC) due to everyone turning on their AC and the campground wiring not being able to handle it. The AC compressor’s motor will continue to run until it (hopefully) trips off due to thermal overload. But over time this low AC voltage condition will cook your compressor’s motor. Not good. They do make undervoltage devices for RVs and suggest you look into one.

But back to your situation. To better understand what is going on, suggest you put in both a DC and AC volt meters. It’s a straightforward project and I found room in my panel to install both. See picture. But if you are not comfortable with this sort of thing, they make AC volt meters that plug into an outlet. And they make cigarette lighter style plug in DC volt meters if you have an outlet like that in your RV, else you have to wire one in.

Let us know if you continue to have issues or need help > that is what this forum is all about!

[Markt1993]

Originally Posted by ESGWheel

The theoretical max per cell of a lead acid battery is ~ 2.1 volts. Thus 2.1V x 6 cells = 12.6VDC. Typically, the RV convertor that powers the 12VDC side of things is a ‘smart’ convertor > it has various states it toggles thru (boost, normal, storage and equalization) depending on what it senses the battery voltage to be and time. Each state has its own output voltage, as high as 14.1VDC. Thus, what you are seeing when on shore power is that voltage, not the battery independently. And when hooked up to your tow vehicle, same thing: the RV is getting its DC power from your vehicle’s alternator. The point being that the DC voltage can very by a few volts and that is normal and your systems can handle that. But your convertor does have it limits. I suspect that the DC side was overloaded and thus the DC voltage dropped to the point where your refer tripped offline to protect itself.



This would not have impacted your Air Conditioner as it runs on the 110VAC shore power. However, it is also sensitive to low voltage. I have seen RV campgrounds go as low as 85VAC (normal is 110 – 120VAC) due to everyone turning on their AC and the campground wiring not being able to handle it. The AC compressor’s motor will continue to run until it (hopefully) trips off due to thermal overload. But over time this low AC voltage condition will cook your compressor’s motor. Not good. They do make undervoltage devices for RVs and suggest you look into one.



But back to your situation. To better understand what is going on, suggest you put in both a DC and AC volt meters. It’s a straightforward project and I found room in my panel to install both. See picture. But if you are not comfortable with this sort of thing, they make AC volt meters that plug into an outlet. And they make cigarette lighter style plug in DC volt meters if you have an outlet like that in your RV, else you have to wire one in.



Let us know if you continue to have issues or need help > that is what this forum is all about!



Attachment 276103

Thanks a ton for your help. I’m at Ocean Lakes at Myrtle Beach, SC. They are celebrating their 50 year anniversary, so very likely is the post lol. I was really worried that the fridge had a issue, low power at the post I can live with. Im going to keep an eye on things and look into the low voltage meters you spoke of.

[ESGWheel]

For the undervoltage protection devices, they come in two forms: (1) portable as in it plugs into the power pedestal and in turn you plug your RV into it and (2) hard wired as it needs to be permanently installed in your RV.

If you are concerned about theft, go with hard wired. And if you go with the hard wired spend the extra bucks to get the remote monitor type. I installed the hard wired years ago but did not go with the remote monitor and is one of the reasons, years later, I installed the AC Line Voltage display along with the ‘override’ switch that can be seen in my picture. The remote monitor type has both of those built in. (Override is to defeat the undervoltage protection in case you need to). I went with the Progressive Industries brand and have been pleased with it these many years. Here is their site on Amazon: https://www.amazon.com/stores/Progre...8?ref_=ast_bln

Good luck and have fun at Myrtle Beach!