DC power issue after installing inverter

[bchoate]

Hi everyone, first post here.

This question is in regards to an early 2000s Gulf Stream Seahawk 5th wheel RV.

I've never owned an RV myself, but I've lived in trailer that I gutted and customized with AC power, water, etc.

I was trying to help a friend get AC power to her outlets while off grid, and thought I could just connect an inverter to her battery and then run an extension cord to the shore power plug. What I didn't realize was that there is a DC converter/charger that tries to charge the battery and provides DC power while shore power is connected.

Having hooked it all up and trying it, AC and DC power were now both working, however, after turning the inverter off (after seeing a pretty big voltage drop on the battery due to the charging loop) the DC power no longer works while the inverter isn't running.

I've looked through every panel I can find, and I did locate the main fuse/breaker panel, but all of the fuses were intact, and no breakers were tripped. However, I've tested the blocks where the DC power comes to the panel and it isn't receiving any voltage.

I was able to find one point where the heavy gauge DC wiring terminates (where it connects to the hydraulic pump) and was able to find the expected voltage there, but somewhere between there and the main panel something has burned out or tripped, but I'm not able to find it.

Does anyone know the solution to this, or can you point me in the right direction?

I'm planning to call Gulf Stream tomorrow, but I thought I'd try my luck here in the mean time.

Thanks!
Ben

[ajriding]

So, on your pic, the battery is on the left, the charger on the right?
The middle breaker is the charger feeding in
and the top and bottom breakers are the battery feeding out.

You should have power on all 6 terminals all the time. These are self-resetting circuit breakers that trip when over-loaded then will reset when they literally cool off. I think there is metal that melts when hot (overloaded) and when it becomes liquid do not make contact across the terminals, but when solid again does make contact, or something like that...

The top and bottom circuit breakers are redundant, and could also be wired into one bigger circuit breaker together, nothing special is going on.

The charger is probably fused internally so it might not even need a circuit breaker as pictured.

Glad you figured it out. Label everything now before you forget the details.

[bchoate]

I do recall that the output of the converter is 45 amps, though I don't recall seeing any text on the breaker after I pulled it off, except one side indicating "battery" and the other something else... (maybe "aux").

The CB that was tripped was the middle one. If you look closely, you can see by the color of the posts that it's installed in reverse order than the others. The copper color post is on the "battery" side. I'm assuming that it was done this way in order to provide surge protection from the converter charger.

The bottom line runs to the hydraulic pump. The other two (including the one that was tripped) run into conduit and go wherever they go. The middle ends up running straight to the main panel (and converter charger) but where the top one goes is still a mystery. It was live the whole time, but there didn't appear to be anything receiving DC power when the converter wasn't providing it.

[time2roll]

OK it looks mostly OEM but I still suggest you check the amp rating vs that small wire coming off the top.

Glad to hear it is fixed but I am not sure it really is. Check the amp rating of the converter and compare to the breaker that opened. I suspect it might be underrated. Wire might be underrated too if the converter was replaced with a higher output. Breaker rating should be 20% greater than the converter max output and not larger than the wire ampacity.

[bchoate]

Also, just in case anyone was curious, I have kept the inverter connected, but moving forward instead of connecting it to the shore power plug, I have just run an extension cord over near the door. If more than 150~ watts is needed, then she can walk around, turn on the inverter, and then pull the extension cord inside for temporary use.

I would be all for modifying and customizing things, but ultimately this is her father's trailer, and she is only using it for one season, so it needs to be returned in similar condition.

[bchoate]

RESOLVED!

Thanks to everyone that contributed. It looks like CA Traveler was our overall winner, but everyone's comments were helpful in getting to the end.

So... what I assumed to just be a kind of "mount point" for splitting the current off to other devices near the battery, was ACTUALLY a set of 3 DC circuit breakers.

After spending a couple of hours tracing and testing, pulling out the main panel and checking behind the power converter (and ultimately finding nothing) I went back to the storage area where the battery is housed and tested each of those points (link to a photo below) and discovered that one of those points was not passing current.

I humorously assumed that they must instead contain fuses, so I then spent 25 minutes turning those nuts off in tight quarters with needlenose pliers and removing the whole unit, only to then bump the little reset button and discover that it's actually a CB. LOL.

Link to the photo here.

Thanks again everybody. Just wanted to let you know of the resolution.

-Benjamin

[ndrorder]

If there is a battery disconnect switch by the door, it will activate a 12v solenoid to make the battery connection. Flipping the switch will coincide with the thunk of the solenoid. Find the solenoid and check for battery voltage on both of the big lugs.

The solenoid will look similar like this:


https://www.amazon.com/INTELLITEC-0100055000-Battery-Disconnect-Relay/dp/B072N8NYN2/ref=sr_1_1?dchild=1&keywords=Rv+disconnect+solenoid&qid=1595853520&sr=8-1

The inline circuit breaker will look similar to this. If it isn't self resetting, a button pops out from the side when it is tripped:

https://www.amazon.com/Circuit-Breaker-30A-12V-CBC-30HB-RP/dp/B00DNG39VK/ref=sr_1_88?dchild=1&keywords=12v+circuit+breaker&qid=1595854104&sr=8-88

[theoldwizard1]

bchoate wrote:
Is it possible there's a switch that automatically disconnects the battery when shore power is connected?

A good electrician (even an amateur) could wire something up with a few relays.

[ajriding]

This should work (plugging into the shoreline extension plug) BUT BUT BUT you must flip the circuit breaker to the converter/charger to off, and also switch the breaker to the refrigerator to off (or just unplug it from the outlet), and do not try to run the Air conditioner.

The battery can supply electric to the circuit breaker panel just fine, the issue is that there are things that need more power than the inverter/battery can supply.

I do not think there is a feedback loop created with the battery supplying the charger that is trying to supply the battery, someone correct me if wrong. If older tech, then the charger is a big transformer, so will not short or anything, but if all new electronics then I do not know details how it would work.
The battery is a big absorber of electrical currents so should handle what is thrown at it in this case.

To do this safely you need to isolate the outlets that can be used with the inverter from the outlets and devices that cannot be run or that you do not want to run off the inverter. You need a switch that chooses A or B where A is shoreline and B is inverter. B will just supply the chosen outlets while A will supply everything (both the chosen outlets and the things chosen not to run off inverter).

Of just keep the inverter out of the electrical system, run an extension cord from it into a power strip and plug in there.

[bchoate]

Thanks for sticking with me on this, guys.

It sounds like I have some more searching to do. I did notice a few rocker switches right by the door, but in my naivete just assumed they were light switches, but thinking back now, I recall that there were labels on some of them (though I didn't look more closely and attempt to read them). I'll go back over there and investigate further.

[BFL13]

No such switch. Whole idea is for the converter when on shore power to recharge and then maintain the battery, so you don't want the battery disconnected.

On our old 5er, the battery disconnect switch was at the kitchen counter and was a push pull knob. Wife kept bumping it without knowing she did it and that would kill the 12v. 🙂

Some have a big red switch handle but it is hard to tell which way is open and which way is closed. Same with those rocker switch types seen in some Class As over the door. (they put two same looking rockers there so first you have to guess which is the house battery disconnect, then guess which way is open)

Some people call those a "salesman switch", can't remember why.

EDIT--sounds like a typical idiotic RV layout for the battery only reversed from the usual. If possible, move the battery to the front cargo bay like many 5ers have theirs, so it is close to the converter and DC fuse panel in that 5er. Saves voltage drop by using short wire runs. Many RVs seem to be based on the idea of using miles of thin wire instead, so the battery is at the other end of the RV from the converter. 😞

[time2roll]

bchoate wrote:
Is it possible there's a switch that automatically disconnects the battery when shore power is connected?

Generally no. When plugged in the battery should remain connected so the converter can maintain a float charge on the battery.

[bchoate]

time2roll:

Thanks for the idea! I didn't check the undercarriage at all. It is a 5th wheel trailer though, so the battery is actually in a storage area in a vented box near the rear of the trailer (under the bedroom). From there, the heavy gauge wire goes straight through the wall, further to the rear to the hydraulic pump, THEN it goes up into a wall cavity and (I am guessing) to the front of the trailer in the kitchen area where the main panel is.

But, like I say, I'll have a look at the undercarriage, maybe there is some kind of box...

[bchoate]

MEXICOWANDERER:

I see what you're referring to, but there was only ever one source of AC (from the inverter I installed). We're in an off-grid situation, so my intent was to allow her to use the installed AC outlets off her existing battery.

[bchoate]

BFL13:

Thanks for the idea, I know I didn't switch anything like this, and the current resident of the RV says she doesn't know of something like this (the RV belongs to her father). I'll do some more looking (especially around the door).

Is it possible there's a switch that automatically disconnects the battery when shore power is connected?