Power rapidly cycling / fluttering on only one breaker

Hi all.
I started a discussion a little while ago about some electrical issues. That discussion was more about my batteries, which were old and have been replaced. But I'm still having issues, so I wanted to start a new discussion to narrow things down.

My current situation is:

* I'm on 50amp shoreline.

* I've got a Magnum inverter + charger.

* My breaker box, inside the RV, has a number of breakers. The only breakers that I think matters for the purposes of this discussion is a 30amp breaker that other 15amp breakers seem to be connected to / through. (Sorry, I'm not an electrician, though I am handy. There are other 15amp breakers that are "downstream" of the 30amp breaker. There's also a 50amp breaker that controls the whole breaker box.)

* That 30amp breaker also controls power to the Magnum inverter+charger.

* There are some outlets in the RV that are through that 30amp breaker, and some that aren't.

I've already replaced that 30amp breaker, just in case.

The Problem:

The power from that 30amp breaker will occasionally start "cycling" or "tripping" or "flickering" or "fluttering". Digital devices (like a cable modem) will power cycle. Analog devices (like a heater) will see their lights flicker/flutter. The Magnum will click on and off about once every second. This has happened in the past few months, but seems to be getting worse, to the point where it seems to be happening once or twice a day now.

I've got a Klein outlet tester (the kind with the 3 lights) and it's lighting up "hot/ground reverse", which I believe is actually indicative of an open neutral. When the power from the breaker is doing this, the Klein will flicker back and forth, in sync with the clicks from the Magnum. A quick off/on every second or so. The Magnum remote, inside, indicates various vault messages: High ACV, AC Overload, Overtemp.

Once the power starts doing this, it doesn't seem to naturally recover. I can sometimes get it to recover back to normal if I turn the breaker off for a few minutes. It might help if, when I do that, I have a decreased load on the other outlets. I can't tell if that actually makes a difference, though.

Note that the breakers do not flip when this happens.

I've replaced the breakers (the 30amp and a downstream 15amp). I've replaced the 50amp plug on my shoreline power. I've replaced the batteries. (Almost surely unrelated but they were old.)

Again, some of the outlets are fine. The outlets that aren't controlled by that 30amp breaker are completely fine.

I've had an non-RV electrician out (there aren't any RV specialists where I am), but he keeps suggesting adding another outlet, which seems pointless to me.

So, questions:
* Does anybody know what the cause could be?
* Does anybody have an idea if the Magnum might be the cause instead of a symptom? (I can't easily disconnect the Magnum, as far as I can tell.)
* Anything else I should do to narrow down the cause? I've got a multimeter and various testers, but I don't feel super comfortable with 50amp power.

Thanks for any advice and knowledge!

bkf
Explorer
Dec 05, 2018
The manual I found for the Magnum says -20° C to +60° C (-4° F to 140° F). It's been cold but not below -8°C. Interesting, though. Thanks.
BFL13
Explorer II
Dec 04, 2018
bkf wrote:
Another update from me. Probably the last one for now, but I've finally "fixed" the issue.

I noticed the Magnum only acted up when the temperatures got down below freezing. I put a 100w bulb inside the compartment with the Magnum, and it hasn't acted up since.

So… no idea why, but my Magnum doesn't like freezing temperatures. Looks like I'll have an extension cord running to that bay until spring :)

My inverter spec says temp range is 0-40C, so that fits.
bkf
Explorer
Dec 04, 2018
Another update from me. Probably the last one for now, but I've finally "fixed" the issue.

I noticed the Magnum only acted up when the temperatures got down below freezing. I put a 100w bulb inside the compartment with the Magnum, and it hasn't acted up since.

So… no idea why, but my Magnum doesn't like freezing temperatures. Looks like I'll have an extension cord running to that bay until spring :)
bkf
Explorer
Nov 22, 2018
dougrainer wrote:
That is a very good wiring diagram. To clarify for you. There are 2 (two) 50 amp breakers in your RV and your diagram shows those. You stated 1 previously and that made me think someone had southern engineered your RV wiring.

Thanks wrt the diagram. Only through the course of figuring all this out did I realize a 50amp is really 2x50amp

dougrainer wrote:
You diagram shows exactly how a Inverter/Charger When on Shore Power, the 120 just goes THRU the Inverter and back to your panel. Since it appears to happen when it gets colder, that points to a LOOSE 120 wiring connection, probably at the Inverter/Charger 120 input and output wiring. Magnums use a screw type system and not wire nuts for the 120 romex wiring. I would check those with a screwdriver. Doug

I talked with somebody else on the forum here and he suggested that it might be those connections, so I replaced all the wire nuts last week. (They actually are wire nuts, not a screw-type system like you mentioned; this Magnum's from ~2012 when my coach was built, not sure if perhaps they've changed? Or maybe I'm misunderstanding what you're describing.) I replaced the original wire nuts with weatherproof nuts (that have the grease inside of 'em). But that didn't seem to help. Same issues. Also, the original wire nuts looked to be well put together and taped.

If you've got ideas for other connections to check, or if I'm misunderstanding, I'm all ears.

For reference, at present, I've got it wired like this. (Note that I hadn't included the neutral bars in the earlier diagram. I removed the neutral coming from the Magnum, and connected the neutral bar on the left (connected to the 50amp breakers) to the bar on the right (previously connected to the outbound neutral from the Magnum. The outbound hot and neutral wires coming from the Magnum into the breaker box are both just wire-nutted.)

I'm still occasionally seeing the fault light kick on on the Magnum's remote screen, so I think whatever the issue was is still happening, but it doesn't really impact me at this point, since it doesn't kill power to the outlets in the house.
FLY_4_FUN
Explorer
Nov 22, 2018
I would like to add that I have recently experienced a similar situation. Mine is a 50A rig but I use a 30A adapter as were never at 30A sites.

Rig has a 50A EMS (for full protection should we ever visit equipped places), and I have 2x 6V GC batts and a 1800W Xantrex inverter. I have relocated one circuit in the rig and hardwired it to the inverter so the fridge and several plugs run off the inverter as needed. My inverter passes 110v to the dedicated circuit on shore power or fires up when shore power lost. At a few places with low line voltage I wake up to my night lights (inverter plugs) flashing on/off every 1-2 seconds. I suspect that the ATS in the inverter doesn't like the incoming voltage but my EMS that protects the whole rig shouldn't act like that. If it gets low/high voltage the whole coach powers down for about 20 seconds or so. I'm stumped if theres an issue with the inverter or if my EMS isn't behaving like my previous 30A version. I suspect a voltage issue is causing issues with one or the other pieces of tech?? Any thoughts? If I change to a better and larger inverter I would like to power up the entire rig with an inverter (minus HW tank/converter).

Daryll
pianotuna
Nomad III
Nov 21, 2018
I hope the Magnum is under warranty. If not, replace it with a Victron, or Outback.

Much as I enjoy "load support", if I had to replace the Magnum, I'd go back to doing double conversion with a stand alone inverter.
dougrainer
Nomad
Nov 21, 2018
That is a very good wiring diagram. To clarify for you. There are 2 (two) 50 amp breakers in your RV and your diagram shows those. You stated 1 previously and that made me think someone had southern engineered your RV wiring. You diagram shows exactly how a Inverter/Charger is wired to a RV with your design electrical panel. The 30 amp breaker GOING to the Inverter is correct. Then the Inverter OUTPUT goes back to the breaker panel and then that 30 amp breaker distributes the power to those 3 breakers next to it. When on Shore Power, the 120 just goes THRU the Inverter and back to your panel. Since it appears to happen when it gets colder, that points to a LOOSE 120 wiring connection, probably at the Inverter/Charger 120 input and output wiring. Magnums use a screw type system and not wire nuts for the 120 romex wiring. I would check those with a screwdriver. Doug
bkf
Explorer
Nov 21, 2018
Hi all. So, I've continued to diagnose. (I'm doing this myself because there aren't any RV techs anywhere near me, and none of the electricians I've tried to hire have any idea about RVs.)

shore power-->50 amp distribution panel-->30 amp breaker-->magnum-->RV outlets?

Yup. Here's a diagram of my breaker box, for reference. (I didn't realize how this was wired when I posted initially. I've been doing lots of learning on this.)

Shore power at home, or in a campground?

Campground.

The next inline diagnostic is not difficult to do work wise but may be a hassle logistics wise.
An alternate source of power.

Here's what I've done: I removed the wire to the Magnum from breaker #3, and ran a 12ga wire from breaker #3 to #12 (and connected the separate neutral bars). So I'm powering the right-side bus of the breaker box from breaker #3, and I've eliminated the Magnum from all house outlets. That seems to have solved the problem. No more power issues at this point. (But also not a long-term solution.)

Assuming it is as you said Power TO the Magnum. not from it. The suspect list:
…
After that the inverter itself becomes suspect.

I did see surges on breaker #1 (one leg of the 50amp inbound power), but I'm not sure if that was a cause, or an effect of the Magnum crapping out (and dropping the load, which I think would show as a voltage surge?). That said, I think it is the Magnum, because… breaker #7 has never had an issue (even when I moved things from #9 to #7).

Electronics on #9 (power passing through the magnum): Fluctuations.
Electronics on #7: No fluctuations.

If it was an issue with surges coming in from #1, I'd expect to see #7 having issues too. But I never have. And, as mentioned above, all the outlets are fine now that I've bypassed the Magnum.

Also interesting: This only happens in late afternoons and nights. That roughly corresponds with the temperature dropping below freezing. I don't know how that'd cause the Magnum to malfunction, or if it's related or just a coincidence. (Maybe the late afternoons and evenings have higher load in the RV park because everybody's using their heaters, and that's causing issues.)

Anybody ever have issues with an inverter/charger having issues with freezing temps?
pianotuna
Nomad III
Nov 20, 2018
so here is what you have?

shore power-->50 amp distribution panel-->30 amp breaker-->magnum-->RV outlets?
MEXICOWANDERER
Explorer
Nov 20, 2018
The next inline diagnostic is not difficult to do work wise but may be a hassle logistics wise.

An alternate source of power.

Of course a 50/30 adapter can be made up with legs L1/L2 transposed. That otter narrow down the suspects.