I don't know from personal experience, but I have heard that with the 2020 there are 3 inverter powered 120vac outlets--the cubby by the bed, one in the bathroom, and one under the passenger side of the dinette. However, these outlet do not work unless the inverter is ON! If you are connected to shore power those outlets will automatically switch to shore power rather than the battery but the inverter must still be on.
I have a Victron shunt and that is the only Victron device in my trailer. The Solar controller can provide a readout of "current" , in amps, going into or out of the battery. It is fairly simple to work out how much power each device uses with just a little time and addition/subtraction. The main attraction of the shunt is it is a "counter" of amps into and out of the battery. For example, if your trailer has used 16 amp hours from a battery...it will tell you that. As the battery recharges, the "counter" will start "counting up".
Multimeters and the Solar controller readouts are still very useful for battery monitoring, they simply take a bit more "practice" and experience to understand what you are seeing.
So many ways to accomplish the exchange and all work well. I have to say though, ScottG document above was well written and lists inexpensive supplies. The job may seem intimidating but reading over the instructions and allowing yourself plenty of time to go slow removes a lot of the stress. The only addition I made was to use a #10 rubber stopper https://www.widgetco.com/products/10-rubber-stoppers?_pos=2&_sid=7e1412c0b&_ss=r and a hollow punch set https://www.harborfreight.com/6-piece-hollow-punch-set-67030.html to fashion a way to hold the ⅜" risers in the expansion tank without a helper.
@immanence you might want to consider a Victron shunt. It's a bit more pricey, but will network with your Victron MPPT solar controller and other Victron devices for better efficiency.
Just to add onto @AnOldUR a shunt can also track and allow you to see how much current (amps) each of your devices in your TAB are using. When you turn on a DC device such as the fridge, Alde, light, you can see the amount of current flowing or amps being used. So it allows you to manage the capacity of your battery when boondocking and estimate when you might run out of battery as you use a device. You also can see when current flows into the battery from solar or chargers.
One reason would be if you have a battery monitor that monitors current through the negative wire via shunt between the battery negative terminal and the negative bus bar.
@ReenieG you may want to hold off on that. The stock factory “wallpaper” is part of the Azdel walls that covers your unit. Here’s a pic of Azdel and what it is. That’s another good reason to never use screws or nails in the Azdel to hang things.
@ReenieG I think this is the one you are referring to, it is great! I can only give you a small part of the address as I downloaded it over 1 year ago. I do not know how to download it to you, advanced age is in the way, it was FOR SALE 2017 TAB 320S FEBRUARY 1, 2022 Hope you can find it Art
We have a 400 and my wife simply used peel and stick wallpaper over the factory wall covering. She installed in on the front wall by the dinette. She got it from Spoonflower and it has been holding up perfectly for the past two years. We've also used in in a couple of rooms in our house and it also has been great. Practically unlimited patterns to pick from. I guess depending on how bad the bubbling on your walls is may affect how it holds and looks.