so, again, I am new to this..

When you say that your phone does not charge properly, are you using a 110v charger with a 12 volt DC output? If so, you may not be getting 110 volts AC at the receptacle that you plug the charger into. You can check this with a multimeter set on AC volt range. Be careful not to touch probes when touching the contacts inside the receptacle. I have a cheap plug-in AC line voltage meter that I leave in a receptacle so I can check AC line voltage at a glance. If you are not getting 110v AC into your rig, you may have a "transfer switch" that isn't working, a tripped circuit breaker, blown fuse or a break in the AC wiring. It is not safe to work on 110 volt AC electrical circuits unless you are sure of what you are doing and take proper precautions. Old RV's are liable to have had two or more previous owners doing DIY fixes, modifying or disconnecting electrical systems.

About the inverter; my experience and that of my friends with RVs is that the 12V convienence outlet is inadequate for most tasks other than low current draw of a few amps. In my two previous motor homes the gauge of the wire from the source to the outlet was not sized correctly and caused a voltage drop. I could not even use a small inverter and a 75W coffee grinder. Fortunately, a power port or cigarette lighter in the dash worked fine. Even if the power port is wired correctly, there is a limit of how much power is available with a plug-in inverter. I have a 400 Watt inverter that has both a plug-in and direct connect option. There is a 150 Watt limit when plugged in. Bottom line is that for any inverter to function properly, it should be connected to a dedicated circuit with wire gauge sized for length and current. Over-current protection is a must.

Replacing the power converter with a modern one is sound advice. It should provide for all your 12 Volt needs with or without a battery connected. When parked for extended periods, I will hit the battery disconnect to avoid overcharging and cooking the battery. My uncle had a van camper with an older type converter that would only work with a battery in the circuit. It had a strange behavior. Even when the battery is a full charge and no power is being used, the converter current draw was very high and the plug arced when insterted into an outlet. Checking with a meter, I found the power factor was extremely low. That is caused when the AC current is out of phase with the voltage. Ideal power factor is 1.0. More than 10 Amps of current when no power is consumed? That is nuts and dangerous. Out with the old and in with the new. A basic 45 Amp converter did the trick.

While we are on the subject of 12Volt circuits, I had a problem with voltage drop to the water pump when working off the battery only. With multiple on-off switches there was too much wire between the fuse panel and the pump. The solution was to place a relay at the pump and run a separate heavy gauge wire back to the source.

Sorry, so I have two issues. One is that when I am on AC, plugged into shore power and using the AC outlet, my phone does not charge well. ALSO, when I plug an INVERTER in (just one that plugs into the old cigar lighter outlet) the light turns orange indicating low voltage. The invereter works perfect in my car but NOT in the RV. Also, I am plugging the inverter into the CABIN electric and NOT the cigar lighter that is connected to the engine battery.

I checked the voltage coming from the CONVERTER and it is 12v. But I am guessing I need MORE than 12 to make the invereter work.

I will attach a battery to the system to see if that helps. I was just looking for some starting points to start problem solving and you all were a great help here. If the battery does not solve my issue, I suppose I will buy a new converter.

I was also told that to use an INVERTER, you need to run a line STRAIGHT from the battery and NOT use one of the lines coming form the converter? I hope that is NOT the case as running a new line will be difficult.

Learn as much as you can about how the converter/charger and house battery system and how the 12volt DC powers your appliance controls and alarms, interior lights, fresh water pump, etc. If your RV's house battery cables etc and wiring are still intact, you could try connecting any 12 volt battery to see if the converter/charger is working. If it is working, you could connect a proper deep cycle RV type battery and all your 12 volt items might work. You may need to replace the old converter charger with a modern one that does not tend to overcharge batteries and quickly deplete electrolyte levels. You should also check whether you have a working house battery disconnect switch/latching solenoid device that lets you disconnect the house batteries when rig is parked for some time without 110vac shore power. That disconnects the house battery from parasitic appliance controls and alarms so that house battery won't go dead while rig is parked undriven for a few weeks. Any battery will self- discharge over a month or two depending on it's condition. Note: Most RV's have no provision for charging the starting battery when connected to shore power.
You may have an emergency engine start switch that connects the house battery to the starting battery in parallel. The same emergency switch can help start the RV generator when house battery is not charged enough. See my post about heeding my own advice.

BluegrassBill wrote:
Converter - 120v to 12v

Inverter - 12v to 120v

This alone probably answers more questions than anything else.

Well done.

Converter - 120v to 12v

Inverter - 12v to 120v

Most old combo converter/chargers won't work properly without a battery attached.... Even an old, half dead battery should get things working. A converter/charger turns household 110 into 12 volts to power 12 volt outlets and charges the battery. An inverter takes 12 volts and makes 110 volts AC out of it. Unlikely you have an inverter built in, I'm assuming the thing you plugged into the 12 volt outlet is a 12 volt to 110 inverter and it is not working properly because the converter is not providing a proper 12 volts. Most old converter/chargers rely on a battery in-circuit to 'smooth out' the 12 volts DC.

Plugging in to your home 20 amp circuit should not cause your 12 volt problems. Unless your trying to run the AC or other high amp appliance at the same time.
To get 12 volt items working you need the CONVERTER putting out 12 volts.
Not sure what you plugged your phone charger into. 12 volts DC or 120 volt AC. I would start by checking voltages with a meter. To see if your are getting 120 volt AC. The move from there to see if your are getting 13 volts or more out of converter.