Converter problem?

RV's don't "switch" to batteries. Batteries are on all the time unless disconnected either physically, or by disconnect switch or blown fuses.

In most cases the RV never "Switches" to battery power.. The one exception I know of is those RV's with a Magnetek 6300 and possibly a few other Magnetek converters.. They actually do SWITCH to battery.

Most modern RV's the battery is ALWAYS there.. it is in parallel with the converter which is what powers the lights et-al on Shore power.... But it also charges the battery.

However there are a few thigns that can prevent it from happening.

First.. Many, I dare say MoST Rv's have a switch somewhere... In my cast the actuall "Switch" is remoted, but the control switch is on a panel just inside the door. on the side of the step well.. This is a common location.

Other locations include the master "Control and sensor" panel, and on motor homes the dash.. Mine is labeled USE/STORE (Press USE and listen for a CLUNK, more on that later) some are AUX (And optionally a MAIN switch next to it, this is on Motor homes only) May be labeled BATTERY or DIsconnect on Trailers.

The clunk.. When I pressed STORE I heard the CLUNK,, but pressing USE did not clunk.. (Dirty switch.. I cleaned it the no-cost way and it hasd worked well ever since) The Clunk is the actual switch (SOlenoid) by the way.

Second... On the battery control center (Where the clunk-er lives) per the manufacturer there are supposed to be a pair of circuit breakers.. PUSH (HARD!!) TO reset type in the bottom of the box.. Mine was done differently but if those breakers are tripped.

Some RV's it is a fuse.

Tribble shooting (yes I'm a Star Trek fan) best tool is an automotove test light
This device, which you can find at many auto departments and every auto parts store looks like an ice pick, the handle is clear or translucent plastic,, there is a light bulb in the handle, and a wire with a clip that comes out of the handle.

Clip clip to battery NEGATIVE, touch battery positive,, BRIGHT LIGHT = Good battery
(Do this when not plugged in)

Move clip to any unpainted metal part of chassis/frame.. Still bright light. Good,, No light,, Check battery negative cable and also clip connection point.

Now move out along the positive cable,, Find where the other end of it connects,, Make sure you get a bright light.. This will be a device with two or 4 terminals, if it is 4 pay attention only to the two big ones (the other two are control power) and touch the 2nd big one. Still bright, keep following the wire.

Each time you move the clip re-check the last good point to make sure you have a good ground.

Problem exists between BRIGHT and DARK.

Your converter is essentially a big battery charger - only works when it's plugged into shore power and sends power to your DC distribution system and your rigs house batteries. When you disconnect from shore power you converter no longer works.

Your problem isn't related to converter but the battery. They maybe dead or one of the fuses between the battery and the DC distribution panel maybe blown. Check the voltage on the battery or have the battery tested for free at any auto parts/tire outlet. Many rigs have an auto reset circuit breaker that sits near the house battery - when that goes toes up it essentially disconnects the battery from the rig - they are inexpensive. They don't look like normal fuse or breaker so use Google to get a pic. Lastly - many rigs have battery disconnect switches - some manual, some toggle, == make sure that those are set in the correct position.

This sounds very much like the battery is not really connected.....due to a disconnect switch being in a wrong position or a loose connection or a blown fuse and the battery charger/converter is supplying the 12 V while plugged in.

NOW would be a good time to get a meter if you don't already have one.

If by "switch to battery" you mean the 110v outlets, microwave, air conditioner, that is normal. None of them do that unless equipped with a LARGE and EXPENSIVE inverter and battery bank.

How many batteries do you have?

What do you mean by "switch"? Do you have an inverter?

A lot more information is needed for any helpful analysis.

What type of RV and model do you have? Do you have a battery disconnect switch?