LOL!
**The basic RV charging system is called a Converter-Charger. Its primary function is to convert 120v shore power to 12V DC power so that your battery does not need to provide DC while you are plugged in. Its SECONDARY FUNCTION is to charge the battery(s) when and if it has excess capacity. It is rated in Amps, e.g. it can produce ~55 amps of DC (for example), which will supply the RVs lighting and appliance circuit boards with power and probably have enough to do some charging as well. **
Totally copied and pasted that. I have sen some rather expensive converters that claim they are true chargers, but it always goes back to the power out is SHARED with the power the camper uses.