First let's talk about terms and components:
is a separate 120V to 12V step down battery charger and you buy these things in different amp ratings (45-100W typically). These units also have a 12V out line for your coach lights and other 12V accessories, which will produce 12V when you ARE and ARE NOT plugged into shore power.
is 12Vdc to 120Vac creates a square or quazi-sine or pure sine wave out of DC voltage and current; and inside the Inverter Box there is a separate 80-100A, 12V charger; and there is an internal transfer switch that automatically turns the inverter function "off" when you plug into shore power... and "on" if there is no 120Vac power present; assuming the remote display control is set to power on the charger and/or power on the inverter.
My Dimensions Quasi-sine Inverter/Charger receives it's 12V power and ground direct from the house batteries. However, there is also a power cable that runs first to the "Boost Solenoid" with a fat jumper to the Battery Disconnect Switch
... and when this switch is LATCHED "on" it will pass 12v to the 12v DC Power Panel. (See push button fuses.) This BDS is controlled by the so called "Salesman Switch" usually located by the entry door.
SHORE POWER WITH 50A TRANSFER SWITCH
Power from shore power first goes to a transfer switch which is just a gate to give priority to the Generator (when it is running) over the 120Vac shore power connection. And out of the transfer switch both L1 and L2 (50A) lines are fed to the MAIN POWER PANEL.
Then a 30A-AC wire wire, out of the Inverter Circuit Breaker, is routed to your Inverter/Charger/Transfer Switch so it can "sense" power from either the generator or shore power pole. ...And if 120V is present it will allow your Inverter/Charger to run; and when no 120V is present the Inverter will do it's magic and convert 12Vdc battery energy in to 120Vac power.
* Out of the Inverter the L1 line goes to 30A SUB-POWER PANEL.
* And out of the Inverter/Charger board sends +13 to +15V back through the 12V positive and negative power cables to charge the batteries.
Note: If you have an 80A charger with 3-12V house batteries, then each battery will receive 80/3 or ~27A/battery. Consequently, if you have a 430AH battery bank that is depleted to 50% SOC, then you it will take (in theory) 430x50% divided by 27A... or about 8 hrs to fully recharge this battery bank back up.
* However, batteries don't like to be "fast charged" and the internal resistance will push back on charging amps. So even healthy house batteries will only reach 90% SOC even when your charger says it reaches 100% and goes into "float mode." Further, you will find your battery bank will last the longest the first day you are dry-camping, but each subsequent day will require you to run your generator more often to obtain the same amount of battery power. (But I digress.)
* Both L1 and L2 are really 50A at the power pole, but the coach wiring and circuit breaker(s) limit power to 30A or 20A and they use the appropriate gauge wire to save money and install the appropriate circuit breaker for safety. (See your power panels for 20A & 15A breakers for the appliance they protect.)
* The BOOST SOLENOID
is a momentary solenoid and is only engaged when you hold down the boost switch. And the only reason you need to do this is when you need to JOIN the house batteries to the engine battery for a JUMP.
Keep in mind my power grid maybe different than yours, but fundamentally, if you do NOT have 30A power to your Inverter Charger, then:
A) Maybe your inverter circuit breaker has tripped or is bad? Do you have voltage to the bus bar?
* NO * ...Then maybe your transfer switch needs to be checked. Just open the box cover with the power disconnected and inspect for visual burns or loose connections.
* YES * ...Then maybe your wire nuts inside the inverter/charger need to be checked for rust.
B) YOUR DIMENSIONS BATTERY TEMPERATURE SENSOR (BTS) MAY BE BAD! This sensor is connected to the NEGATIVE house battery terminal and the part #611622-15 for $35 direct from Sensata/Dimensions. Call 855-633-7257. This is a "thermal resistor" that acts as a safety switch to turn you inverter/charger off in the event you batteries over heat. (See Picture.)
C) YOUR DIMENSIONS CHARGER IS BAD...and at that point you can do two things:
* Replace the inverter charger which is expensive, but you can get an upgrade to a pure sine inverter, which may or may not be worth spending your money on, because the Dimensions Quisi-sine Inverter produces a good enough sine wave to power a residential refrigerator, but may not be "clean enough" for any medical equipment? IDK.
* Keep your Dimensions Invert and just turn off the charger at your remote panel. ...Then buy a separate Converter-Charger and tie into the inverter-out L1 wire to power it; or if you want a switched outlet, you can plug the Converter-Charger into engine block heater wall socket that is already there. Then you can turn the Converter-Charger off from inside your coach.
Note: Victron is making some very cool "bluetooth" enabled products that let you use an App on your cell phone to control their products.
Note: You don't need the Converter 12V wire, but maybe you can utilize it for something else? Maybe run it to the engine compartment to power a 12V scavenge pump to make your fluid changes easier.
I personally have no need for a pure-sine wave inverter, but if you do this is the time to upgrade. I.e., whenever you have to spend money to fix something, then why not spend a little more to upgrade?
And if I lost just my charger, I would look at keeping my Dimensions inverter and add a separate charger.
I did just order this Victron Battery Maintainer which also has bluetooth so I can monitor and control this device from my cell phone: