Hi Electrical Wizards,
I'm in the process of planning/procuring my electrical system components and am having some issues planning my AC and DC setup. I want both 12V DC and 120V AC in the trailer, basically at all times, with the 120V being fed from shore power when it's available and from an inverter when boondocking/shore power unavailable. Yes, I could get by without 120V when away from shore power, but I am looking to have everything available in this trailer from the start. I don't want to regret not putting something in now.
I have already purchased a Progressive Dynamics PD4045 which I was intending to use for my 12V and 120V distribution. This would also charge the batteries when plugged in to shore power, and provide 12V power without using the battery. Seemed like a good solution initially and then the integration of an inverter came into play.
The problem I have is where can I integrate the inverter in the system to provide my 120V? I was hoping to utilize the PD4045 for all of my 120V distribution, meaning I would feed my inverter into the 4045 so that all the outlets in the trailer work the same on shore power or battery. However, while boondocking this setup leads to the inverter pulling from the battery to provide 120V AC to the PD4045 which sees the AC and then wants to charge the battery... not good, and on shore power it would mean the inverter is also feeding the 120V panel.. even worse.
The solutions I've seen mentioned / thought of:
1) Get a DPDT switch that can switch the inverter on and disconnect the PD4045 converter. This way I have 120V AC and the converter when on shore power, and when boondocking, throw the switch and now I have 120V AC from the inverter, and the PD4045 converter disconnects and it can't try to charge the batteries. A problem could arise if plugged in to shore power, and the switch is thrown turning on the inverter. Now I would be supplying two 120VAC sources to one bus bar. I'm no electrician, but I am thinking this could let out that magical smoke which makes all things electronic work.
2) Don't feed the inverter to the PD4045, and supply power from the inverter separately. This will mean using split outlets, or separate outlets for shore power and inverter power. This keeps things separate and no need for switches, but I will have to remember which outlets are which. I could also get an inverter with transfer switch, and have it fed from the battery and the PD4045 which would pass through the 120V when on shore power. This way all outlets are live on shore power and only some on battery power. No possibility of two AC sources on the same bus.
3) Return the PD4045, get an inverter that charges the battery and has an automatic transfer switch which will run all of my 120V AC, and charge the batteries on shore power (like this Renogyhttps://ca.renogy.com/2000w-12v-pure-sine-wave-inverter-charger-w-lcd-display/). Then just have a simple fuse block for my 12V distribution, and a small 120V panel for breakers and distribution (or none at all). The downside to this is the inverter has more components and will be more expensive to replace if a part of it goes. (I kind of have that problem with the PD4045)
4) A combo of 1 and 3. Toss the 4045, get a 12V fuse block, 120V panel, battery charger, regular inverter without transfer switch, and a DPDT switch. Have shore power and the inverter tied into the panel, with the DPDT switch set up as before. On shore power you can charge batteries, have 12V system, and 120V system. On battery, throw the switch and now the inverter provides 120V and the battery charger is disconnected. This has the cheapest components and each is easily upgradable and replaceable, but has the same problem as before and possibly supplying two 120V phases to the same panel.
Would appreciate some thoughts and feedback from anyone who has a similar setup or another solution I'm missing.