Phantom Voltage

[llr]

Some inverters have the battery charger built in. If this is the case that would replace the converter.

[Scrapper]

Originally Posted by CNacc

When I bought this camper brand new at a dealership in Florida the dealership manager said the camper had a inverter for the refrigerator but it doesn’t have a converter for charging the batteries..
I would disconnect the batteries but I found out that only 2 of the 4 six volt batteries were actually being disconnected. So this lead me to try and understand the camper electrical system and in doing so I found what I called a phantom dc Voltage that was between 13.5 and 14.5 vdc but it was intermittent and I found this out because it was powering my propane gas alarm and when the voltage dropped below 8 vdc the alarm would sound. So remembering that the dealership said no inverter and my batteries were taken out of the camper and I was only hooked up to shore power what is generating this dc Voltage. Well now I know.
I now have other questions like why do I have 2 inverters and I’m trying to see how the output from the inverter is connected to the batteries.

What you most likely have is 1 inverter and 1 battery charger. As mentioned before the converter is nothing more than a battery charger. While you have it plugged into shore power and the batteries disconnected the charger is supplying the 13-14vdc.

You also say when the batteries are disconnected you see 13-14vdc then it drops til it reaches 8vdc then comes back to 13-14vdc. How quickly is the voltage drop and recovery back to 13vdc? If it's a matter than a few seconds then the electronics in the charger is bleeding off residual voltage until the charging circuit kicks back on. In this case the charger is not a modern electronic one that that will sense the batteries are missing. The charger most likely has large capacitors inside that charges up then discharges. Sorry, but this is the best explanation I can give you about the fluctuation your seeing while the batteries are disconnected.

If you don't have the documents from your dealer for the charger & inverter and you can find the make and model numbers of both the charger and inverter you can find the documents on the manufacturers website. The documents will have the wiring diagrams. You may have to use a mirror or your cell phone camera to find the labels.

[formerFR]

doubtful...

some manufacturers DO provide TWO different inverters... as they may do this to limit both the upfront cost of a larger 'whole house' model, and because it may be simpler, wiring wise, to have a separate one for the residential fridge, for various reasons. The evolution of these motorhomes sometimes dictate how the factory choose to 'redo' wiring for new floorplans, versus out-and-out re-engineering of the whole coach wiring plan.

Since the advent of residential 120v fridges, growing increasingly common even in 'smaller' coach floor plans, as more folks desire and demand them, the integration of a 'fridge only' Inverter came into play. For the most part, it only provided juice to the fridge, but as more time went by, more factories chose to add at least a few other outlets, making the need for slightly larger Inverters...

Then, some changed their floor plans to give folks more of a 'whole house' Inverter system, with many, if not all, outlets on inverter power, but at the same time, that meant changing the current Electrical Panel setup, moving away from a 'Converter' based unit, to one that has none, since the additional SECOND Inverter now will charge the batteries, providing the same 'outcome' as a Converter would. A single LARGE inverter might be cost prohibitive or require more costly wiring changes, so they chose to keep the separate fridge inverter, and add a Second 'outlets' inverter, which also includes a battery charger.

While it may seem counterintuitive to have two inverters, actually several large motorcoach manufacturers, like ENTEGRA COACH, provide TWO inverters, both very LARGE inverters, such as the Magnum MS2012, and BOTH have battery chargers, but these units also may have 6, or even 8 House batteries.

So, yes, you could certainly have two different inverters, but one is a 'dedicated' unit, probably only for the fridge, not run thru the Main Electrical panel, while the other is for the rest of the outlets, IS run thru the electrical panel, and ALSO includes a battery charger.

Fun !

[formerFR]

"I’m trying to see how the output from the inverter is connected to the batteries."

The inverter is not 'connected to' the batteries, but is provided power FROM the batteries - so yes, it's physically connected to them, but for only in one direction.
But, many inverters have a battery charger, which means that there will be a connection from Shore power, or Gen power, thru the Main Panel, to this Charger, which is integrated within the Inverter.
Chances are, you have both a 'Charger' circuit breaker, and an 'Inverter' circuit breaker, though they do not work the same way:

I'll give you an example, mine: I have a Magnum ME2012 Inverter/Charger.

- 120v Shore or Gen power comes into the Main Panel via the ATS(auto transfer switch), into and thru the 50amp double pole breakers(two hot legs of up to 50amps each)

- each hot 'leg' serves every other circuit breaker, with it's own Power Bus bar... meaning that Air Conditioner breaker #1 is on the left leg, Air Conditioner breaker #2 is on the right leg, the Elec Water Heater #3 is on the left leg, and the Battery CHARGER #4 is on the right leg,etc.
This Battery Charger breaker receives 120v power, and sends it to the Battery Charger, which is within the Inverter unit.
The output of the battery Charger keeps the House batteries charged, at least while on Shore or Gen power, of course.

- I also have another breaker, on the far right side, named INVERTER, and several 15amp 'tandem' breakers to the left of it. All of these are really on a 'sub panel', integrated within the panel, since these 15amp branch breakers supply all the outlets in the coach, even the fridge and microwave outlets.
This Inverter breaker actually 'receives' 120v output FROM the Inverter, in a reverse direction to the normal breaker wiring, and to its 15amp branch circuits via the power bus bar behind it, that they are all attached to.
This is actually exactly the way the Progressive Power builds these Main Panels for these coach systems. The panel has THREE power bus bars - two for the 50amp hot legs, and the 'sub panel' power bus bar for the Inverter power. Strange, but true. and Fun!

[CNacc]

Clarification .... I have 1 Inverter Connecticut to my batteries and feeding 120 volts A/C to my refrigerator only.
I have also just located 2 Converters side by side WFCO Model 9855
55Amps each
I’m not understanding of how they are used in the system
So let me explain what I see. Both Converters are plugged into 120vac outlet and on the opposite side there is a Heavy Red wire and a heavy White wire ( like a #8 or #6 awg wires. The question is both secondary side of these Converters are going in 2 different directions. One towards the front of the RV and the other towards the back.
I’m saying it this way because till I can physically see where these wires are connecting to I won’t speculate. But if you guys have the answers please let me know so I can speed up this troubleshooting. Right now I am removing the sewer pipe storage tube and trying to disconnect the central vac system as well as disconnecting some of the water lines... All of which are on top of The Converters. Once I have access to them I will check the fuses and maybe, relocate them both.

[formerFR]

sounds like you have two converters/chargers to TWO battery banks ... one for some 12v items, and the other for everything else, 12v related. If you have four House batteries, and even though they may be in the same area, they may be only wired in Parallel, and separately, creating two different 12v sets. One set is for the fridge and it’s inverter.

This may be why you are finding 12v power even when you ‘thought’ you had disconnected the batteries. You may have only affected one set.

[CNacc]

I took out the 2 converter and checked the fuses both ok. So I plugged them in on my work bench and this is what I got
Convert #1 when I plugged it in to 120 the fan came on for about 3 seconds and then stopped. So I connected a small little 12dc tire inflator and put my meter also across the output. The inflator started to barel run and I was showing 13.5 before I hooked up the inflator and as soon as I did the voltage dropped to about 2-3 vdc
Converter #2 both fuses also checked good but no dc Voltage showing on output, no fan was running and when I connected the tire pump nothing happened and still no output voltage.
So I guess I need to purchase a upgraded Converter and my question is this Do I purchased 2 and installed them as the original or do I buy a better one but then how do I wire my 2 different battery circuits ?
Right now like you said I have 2 six volt batteries in series powering my house and 2 six volt batteries powering the inverter for the refrigerator. I don’t like it this way because the emergency shutoff switch is only on 1 set of batteries for the house , if possible I would either install another emergency disconnect switch for the other side. Here is another question, my truck alternator is sending voltage to only 1 set of batteries, question is if I hook all 4 batteries in 2 series parallel circuit like I think they should be , then would the truck alternator be under to much load ?
Any thing you can input on would be helpful. Thanks again
Chuck

[Duckogram]

Your TV alternator will only send excess voltage to your batteries. Probably not enough to charge 4x6v but better than nothing. The split bank was most likely done to keep from killing the fridge batts while camping. I believe your inverter is a zantrex 800 so two 6’s will power it for 3-5 days under normal use. If you combine both banks you will need to do a lot of reconfiguring of your 12v house system. From the cheap seats, I would just get a replacement for the one converter that does not charge.

Edit: I think if you turn the inverter off (switch on the front) you will have essentially disconnected the pair of dedicated batts. You would have to put a meter on it to verify that.

[CNacc]

There both WFCO Converter Model WF-9555