RV and Roof Solar

[RichTate]

Will,

I've watched so many of your videos, really enjoy them! I especially like the testing you do on batteries so that now I've just ordered my first LifePO4 12Vdc 200Ah battery.

But I'm confused by the solar systems you setup in that they don't explicitly incorporate all the power systems on my RV. I have a 12Vdc system and 120Vac system and I understand how to connect the solar system to those, mostly. But when it comes to the solar controller to charge the battery, how do I connect all the other power systems?

For instance, when on shore power, there is a 12Vdc battery charger. When I'm connected to my truck there is my 12Vdc system from the vehicle that charges my RV batteries. How do all these charging systems get incorporated with the solar system that I want to install on my RV?

The reason I want the solar system is that my RV has an efficient 120Vac refrigerator that works on the 12Vdc system via a 1K inverter (pulls 315 watts). But it can only run for 4 hours on the current lead acid batteries. So I want a better battery and solar to keep them topped off and be able to run the refrigerator all day and maybe into the evening if boondocking/dry camping.

I don't want to hurt the new LifePO4 battery I have coming with a small 360W solar panel/system that I want to be able to expand at a later time. I was going to use the Victron MPPT 30A on your website but don't see how to connect it with all the other 12Vdc systems mentioned.

Do you have a video that takes all the individual 12Vdc systems and connect them all together? It needs to work under these conditions:

1. Boondocking/dry camping - allow for running generator as needed.
2. Towing - charge batteries off tow vehicle 12Vdc system
3. Shore power - maintain 12Vdc system while connected to external power.
4. Generator running - all add separately but used when dry camping.

Again, thanks for your videos and website, but I just need these diverse systems added to the solar system equation!

 

[dashdrum]

1. You're set with solar panels and a charge controller

2. Unless you have setup a DC-to-DC charger and appropriate gauge wiring between the tow vehicle and RV, you won't get enough power during travel to make much of a difference. The small amount of amperage that flows through the 7-pin connecter is designed to charge the small lead acid battery that was probably stock equipment. However, roof mounted solar panels are still operational when moving.

3. This is a little more complicated. You will need a transfer switch, auto or manual, that can switch between inverter and shore AC power. The shore line and inverter AC output are connected as inputs, and AC power from the switch will go to the circuit box in the RV. Second, the 12V converter that charges a battery may not be appropriate for a LiFePo4 battery. Check the specs to be sure. You have the option of replacing the converter or adding a lithium charger, but make sure these are turned off when not using shore power.

There are so many more details for each of these points. Research is your next step!

 

[RichTate]

Thanks dashdrum! Those are the areas that I need guidance. I also noticed that there is a 4th condition, when boondocking, I run a generator, so there is an automatic transfer switch for shore power and generator power, would need to add the inverter to that also...

Yes, lots of research... A schematic would be great! I can read those and that would answer all the connection questions I have.
Thanks again!

 

[dashdrum]

In my case, the generator is not built in to the RV, so it follows the shore power model. I have seen examples of a two transfer switch setup. First one switches shore and gen, and the 2nd takes that output and switches with inverter.

Best of luck, and keep us posted!

 

[dashdrum]

Here are some videos/articles on the subject that helped me:

Converters, Inverters, & Transfer Switches

How this article is ordered: The BasicsHow They Tie Into An RV SystemInverter RecommendationsDisclaimers THE BASICS Lets get you familiar with what these things are, then we’ll talk about how…

www.imnotlostimrving.com

RV Inverter Setup. How To Power It All! 30 and 50 Amp – All About RVs

allaboutrvsinfo.com

 

[HRTKD]

If your RV has shore power and a generator already then there is a transfer switch already built in. If you can be plugged into shore power and fire up your generator and don't have fire and smoke then you have a transfer switch.

The solar charge controller needs to connect to the battery. It's (mostly) that simple. You can have shore power, generator and solar all producing power at the same time. My solar charge controller will see the power that the generator is feeding into the battery and the controller will cut back to zero the amps that it is capable of sending to the battery.

 

[tictag]

@RichTate, does this help visualise the full system?



It's fine to have multiple charging sources simultaneously connected to your battery, they will all contribute to charging the battery and will never allow it to overcharge, though you might need to take care to never exceed the maximum charging current specified by your battery manufacturer.

You might also want to switch out your charger if connected to shore/genset if you want to maximise PV charging.

p.s. ExtConn is external connector

p.p.s. Some inverters have an in-built ATS, like the Victron MultiPlus, for example.

p.p.p.s. Some RVs will have the charger and towing electrics contained with their PDU (Power Distribution Unit, also known by other names)

edit: Added post scripts.