RV Power Conversion (Not to be confused with power INversion)- rversonline.com
RV Converters, actually have a very simple task (supplying 12 volt power to lights, pumps and fans), but because their basic function is shrouded with fuses, and circuit breakers, converters appear to be more formidable than they actually are. Most RV converters are composed of the following parts:
1. Battery substitution power supply. Chew on this description for awhile "Battery Substitution?" "Power Supply?" Yep! That's all that it is, a humming transformer that reduces 120 volts AC down to 12 Volts, and a couple of Diodes, to convert the 12 volts AC to 12 volts DC. When the converter is connected to shore power, is makes it own 12 volts DC to a limit of about 30 amps of power, and your rig's coach battery is switched out of the circuit by a relay. But, what about the fuses?
2. The converter box is a handy place to hang all of the 12 volt DC fuses.
3. And it's also a handy place to hang all of the AC circuit breakers (one of which is used to switch the converter AC inlet power on and off).
The relay only operates when you plug your rig into shore power. The relay closes off your house battery and allows the battery substitution unit to power everything in the coach. When the rig is disconnected from shore power the relay clicks back to a different set of contact points, and your rig will then be operating off of your house battery once again. Shore power is transformer power, house power is battery power, as far as your lights, heater, and pumps are concerned.
Battery charging occurs because the converter manufacturer, installed a "Bleeder Resistor", which acts like a trickle-down reducer valve, between the converter-to-house power connection (the one that feeds all of the DC fuses in the face of your converter box), and the battery connector, located right before the relay. When the converter is humming away on shore power, the bleed resistor allows a small fraction of the converter's 30 amp potential to be siphoned off to "keep the house battery charged". Most converters only allow three to five amperes to "bleed" through to feed the house battery. This is a primary reason that attempts to recharge a flat house battery using an on board generator, fail miserably. Flat batteries require a minimum of thirty to forty amperes of power to recharge quickly. A three amp charge rate would take forever (and it usually does - most people give up after three or four futile hours of running a thirsty generator to recharge a flat battery).
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