Alternator, generator, shore power, inverters, solar... (bus wiring)

[Jnbroadbent]

So here we are, wiring the bus, spent countless hours researching and I'm still a bit  on the whole system working together.

So we've got  the alternator, generator, shore power (120v), inverters, solar panels, batteries. I understand how each system works individually but I'm very confused on how to tie everything together.

120v/50amp will be able to power all 3 roof top ac's and all the accessories obviously. But then how do I switch over to the gen or alternator/inverter or batteries/solar? Are there any reliable automatic systems? And then some systems need power 24/7 such as the fridge and the lights.

And we had intention of everything being 120v. Sorry for the very broad and uninformed post....

[bevans6]

I'll tell you how I did mine, and why, but your application and priorities will drive your decisions.  I wanted to stay with a 30 amp service, since many times I would expect to not have access to a 50 amp plug.  I wanted my source logic to look like this:  first external power, then generator power, and only if they were not available then inverter power.  I used a simple automatic transfer switch to select between external power and generator with the switch priority feed to the external power source, and the generator on the secondary feed.  The output of that switch feeds a small distribution panel for outlets that I did not want on the inverter, and it feeds the inverter input.  The output of the inverter feeds another small distribution panel for all the loads that I want to be on the inverter, and the inverter is the battery charger.  The inverter has a built in ATS so that it passes through external or generator power to all of its loads when those sources are available.

It all works quite seamlessly.  If I am on external power, all of the outlets work and I can run my air conditioner.  If I am parked with no external power, I run the generator if I need the AC, and then switch to inverter for quiet hours when the AC is off.  If I am on the road I run the inverter from the alternator power and can run the AC for cooling.  I have a 235 AH 24 volt house bank that is tied to the 250 AH 24 volt start batteries with a marine A+B switch so I can have the house batteries charged by the alternator, run the inverter from the alternator, or separate the start batteries from the house batteries so there is no chance of running them down with excessive inverter use.  I can also use the house batteries to boost the start batteries on cold mornings.

This might give you some ideas on how to manage your application.

Brian

[gumpy]

It's not automatic, but the simplest is to have a female outlet on each power source, and a male plug on your distribution panel. You plug in the male to whichever power
source (shore, generator, or inverter) you wish to have powering you bus.

So, when plugged in, the panel plug is connected to the shore line receptacle. When you depart the campground, you may want your inverter powering, so you plug it
into that receptacle. While boondocking, you might want the generator running for A/C. Anyway, you get the picture. You can modify it depending on your equipment.

I didn't go this route, because I'm not smart enough to do anything easy. I built a transfer switch which switches as necessary for the power source providing power, either
50 amp shore, or generator. Inverter is always part of my system as it is also the battery charger and has a transfer switch for incoming power (only one line, though).

[Geoff]

You will have to go with a 50 amp shore line, and build your own transfer box for the generator and shore power.
You will need two Grainger 5X847 relays and the 4A079 box to build your own transfer switch.  The transfer box relays can be wired for a 50 amp shoreline imput that overrides either a one-wire or two wire (single 120 leg or two 120 legs) generator output with a ground transfer.  The solar power goes to your battery bank by itself with its own regulating system, which supplies the inverter.  The inverter should have its own transfer switch.  Oh, and with this setup your 120 inverter will only work on one side of a 240 circuit breaker box.

Sorry, no diagram.  This is how I wired my bus 10 -12 years ago and I did it without a diagram.  Works perfect.

--Geoff

[Seangie]

Jon -

I like the KISS approach.  As previously stated, I'll tell you how I did mine and you can decide for yourself.

First think about how you will use your bus.  We are on the pole a bit so we don't run our generator much.  When we do boon dock we only to run the genny for stuff on the 120v outlets as we have wired most of what we could to the 12v system.  If you are going to be heavily boondocking it may be much different for you.

120v-
Our 120v system is a house 100amp service breaker panel.  Ill spare the details here. But it has a 50amp plug coming out of it that we can plug into one of two female 50 amp recepticals.  One for genny power and one for shore power.  Craig (gumpy) explained this above.  We are going to wire in a transfer switch at some point but that is how our bus came so for now we are keeping it that way.

Inverter-
For the charger/inverter we have a 30 amp breaker on the house panel that feeds the charger/inverter. This is the source to charge batteries.  The charger/inverter has a seperate sub panel with (2) 15 amp circuits that feeds 2 outlets in the bus.  ***I'm going to break in here and say that there are a few ways to wire in an inverter and you really need to research and figure out what works best for how you will use your bus, type of inverter and battery bank that you plan on having*** The inverter/charger will pass through the 120v when it is available and when not available it switches to inverting battery power.  Keep in mind that we have 3 outlets (on 2 circuits) total for inverted power and that's all.  Nothing else (hot water, fridge, microwave) is directly wired to our inverter.  So if we need the inverted 120v we have to plug something in to use it.

12v-
We have put as much as we could on the 12v system.  Lights, fridge, fans, charging outlets for phones, etc.  This will run off the alternator when we are rolling, run off batteries when we are parked and run off the charger when its charging batteries when plugged in or on the generator.  The house batteries and the starter batteries can be tied together so that when we are rolling the house batteries are charging and the fridge, lights and fans are all running on the alternator.

I think that's it for us.  Simple enough?

-Sean





Fulltiming somewhere in the USA
1984 Eagle 10S
www.herdofturtles.org

[TomC]

I have three systems-direct, inverter, 12vdc. Direct gets power either from shore power or generator. That includes-refer, secondary water heater, 3-roof airs, washer-dryer, freezer, radiator blower and ventilating fan for the generator, 30 amp powering the inverter.
The inverter has an automatic switch over that will allow 30 amps to power through from the main box, or 2,500 watts inverted from the 2-8D deep cycle batteries. Items powered through the inverter is primary water heater, bath heater, most all plugs, microwave, toaster oven, stove hood, both T.V's and stereo.
What's left is straight 12vdc-most all lighting, freezer and refrigerator (both 12v/120v compressor type), 2-water pumps, 2-Fantastic fan roof vents, propane solenoid cut off, furnace, antenna amplifier.
The only propane powered items is the stove and furnace.

To switch from shore to generator, I have a simple either or circuit breaker. Very simple, but manual system-one that has been faithful for 20 years. Good Luck, TomC

[bobofthenorth]

I expect the longer you read the more confused you will get because there will likely be as many permutations of systems as there are posters.  Our system is as follows:

50 amp shore service with one of the 110 legs wired through a Heart 25 inverter in pass through mode.  Effectively that leg is limited to 30 amps because the Heart internal transfer switch is 30 amps.  The main house loads with the exception of the AC and the hot water heater are on a distribution panel on that leg which means in practice that we can run everything except the hot water heater or AC off the inverter, within the 25 amp output limit of the Heart 25 of course.  Both legs of the shore service go first to an auto transfer switch which is priority to the shore connection.

6.5 kw Onan genset wired to the same transfer switch so all the features of the 50 amp shore service apply equally to the genset.

3 x 8D Lifeline AGMs to supply the inverter.  They are charged by the inverter and also by 200 watts of solar panels.  That's not even close to adequate solar but it keeps the batteries topped off in storage and helps out a bit in strong sunlight.  We monitor the batteries with a Trimetric 2025 - if you are going to use your batteries at all then some kind of battery state of charge meter is essential and I am a big Trimetric fan.  Most of our coach lighting is 12 volt LED, a lot of which I built myself and, despite dire warnings to the contrary they have neither failed immediately nor burnt my coach down, yet.  We have 110 volt and 12 volt reading lights beside the bed, both voltages in the head and in the living room but the entire lighting in the galley is 12 volt.

I have some fancy dancy solenoid that Tom Caffrey recommended to connect my house and coach battery banks while the engine is running.  That keeps the house system more or less charged underway, although heavy inverter use while we are travelling will still pull the house bank down some.  It also means that the house bank supplements the coach bank for starting which in practice meant that my starting bank was pretty well dead before I realized it was failing.

[Midwilshire]

Our system is as follows:

50 amp shore service with ....

Bobofthenorth, your system looks a lot like what we want to do.  The only difference is that our automatic transfer switch will be voice-activated and will only work while my wife is awake.  Do you happen to have a schematic or other type of diagram for your system? 

[bobofthenorth]

I'm not big on drawings so no, I don't have any diagrams.  Its a pretty basic system though


Generator -----------
                              TRANSFER -------> One leg into panel for AC & water heater
                               SWITCH -------> One leg into inverter wired as pass through ---> panel for all other loads
Shore power --------

[Melbo]

My set up is similar to Brian's or BOTN. HOWEVER I do have resistors on all my LED lights. If you are going to use a lot of batteries as Bob suggested the trimetric is very helpful in keeping track of things.

I do have a diagram at the bus. I will try to get it and post it here for you.

The biggest decision you will have to make is what you want to be inverter powered (this will also be what works on the road with power supplied by the generator). I have labels on many (not all) of my inverter powered outlets so when I am parked I know what will have power. The rest of the outlets and appliances will only work when the generator is on or we have shore power.

HTH

Melbo

PS You will want to check everything (I mean EVERYTHING) for amp draw using whatever power source you can and write it down so you know what you can and can't run at any given time. I have electric fans that cool the generator so when the generator is on they draw big time AND when you start the generator or plug into a land line the inverter becomes a charger and can draw a lot more power than you would think.

[Jerry32]

I just used a 4KW inverter with built in transfer switches for AC1 and  AC2 as well as auto transfer from and to inverter. Jerry

[Jnbroadbent]

Thanks for everyones input. I'm going to get a diagram going on my build idea and post it here to get some input. Cheers

[Melbo]

Here are my drawings from my "owners manual"

HTH

Melbo

[Uglydog56]

My setup is pretty similar to Melbo's very helpful drawings.  The solar panels go to their own controller.  The controller output will attach (on Melbo's drawing) between the disconnect and the fuse on the red (+) wire, and between the shunt and the ground connection on the black (-) wire.  Then you will be good to go.

I wired "vital" loads (like the coffeemaker and the TV) to my inverter subpanel, and "non-vital" loads (like the bathroom receptacles for my wife's hairdryer) in the main panel.  My inverter has a pass-through so the loads on it are powered from the generator or shore power if available, like most people's.

My lights are all 12v.

One difference in my setup compared to others already discussed, is I have a dedicated small inverter for the refrigerator.  I use a separate thermostat that is AAA battery powered, that turns the inverter on and off, to power the compressor.

[Midwilshire]

One difference in my setup compared to others already discussed, is I have a dedicated small inverter for the refrigerator. 

Why did you do that?  Did it draw too much from your other inverter?