Before you start running wiring of any type.  Or cutting holes in your vehicle, sealing up walls, etc.  Or starting any type of anticipated power system.  You need to consider all component options. 

A Converter – Charger is generally one of the basic foundation building blocks of any mobile RV type “house” electrical system.  Integrating both 115VAC and 12DC sources, and outputs, as well as charging sources.

A Converter – Charger‘s main function, is to “Convert” Park Power (120VAC) to Battery type power (12VDC). 

In this Converter component, a 12VDC Smart Charger, is in turn, wired to your auxiliary “House Battery”, or “House Battery Bank”.  The Charger recharges any consumed stored battery bank power. 

Once the batteries are fully charged.  The Smart Charger goes into a “Float Mode” to properly maintain the batteries without overcharging them.  This is all done thru wiring that is permanently attached.  

This is just a simplified explanation of the very technical side of charging batteries.

At the same time.  Through a common Link or Bridged electrical path.  The 12VDC feeds onto a fused 12VDC Distribution.  This fused distribution is where you would terminate all your builds “House” 12VDC circuits.  Things like 12V lights, 12V water Pumps, 12V Charging ports, 12V fans, and appliances that require 12V power for igniters, or 12V Blowers.

You don’t have to fiddle around attaching alligator clamps from a battery charger, or flipping any toggle switches to turn things on, off, or put something in bypass.

If the 120VAC source is unplugged the 12VDC from the battery bank, continues to supply 12VDC to the fused distribution and loads/circuits attached there.  This continues without interruption as long as the charge on the battery bank remains adequate.

The unit also provides many system components, some of which will be mandatory or necessary anyway.  Components such as a Main AC Breaker, Branch Breakers, fused DC Distribution, and a Smart Charger.

We reference a Progressive Dynamics PD4045 often in many of our webpages.  In reality, there are more than just one brand, and numerous models under any brand.   Another popular RV brand is WFCO. 

Both brands, in several popular models, are readily available at retail places like Camping World and specialty businesses that cater to RV and Trailer parts.  Definitely available on-line from numerous sources.

Options for selection of a model, depends on the type of charging output the unit produces, and whether that output is for “Flooded”, “AGM”, or “Lithium” type batteries.  Some are manually adaptable through switch setting or programming.

More recent models are becoming auto-sensing or auto-adaptable.  The units output charging characteristics must match up to your battery type. 

For the most part you can’t mix battery types and charger types that are not the same, and compatible.   There is some technical information you will need to know, or have someone knowledgeable walk you through.

Some Converter Chargers may even include integrated Inverter capabilities.  We aren’t going to touch on those. 

Any of these various units are the heart of a safe and well wired electrical system.

A Converter-Charger unit will provide various minimum requirements.  Basic requirements you might otherwise have to cobble together, out of multiple other electrical components.  In cobbling together a system.  You may inadvertently omit something important, not knowing better.

In the long run, the correct Converter-Charger will most likely save you money over installing multiple stand alone components, provide required safety features, and in the end create a much more organized and compact electrical installation.   Best of all you won’t be tearing up your build after the fact to add something in.

Most techs that work on any kind of electrical system, will tell you a neat and tidy installation, will be the installations that do not have faults and failures.  Or the type of installation that requires constant troubleshooting.  If your installation looks like a mess, it most likely is exactly that electrically.  A recipe for an unsafe build.  A headache to troubleshoot when something doesn’t work.

All vehicle or trailer conversions that are going to eventually attach to a 120VAC source.  Such as park power, your home via an outside 120VAC power outlet and extension cord, or a generator producing 120VAC.  Should in all cases have at least a Main 120VAC Circuit breaker at the “Minimum Point of Entry – MPOE” inside the vehicle.

Minimum Point of Entry commonly refers to somewhere within 3 foot or less, concerning the main entrance Power wire.  At that 3 ft or less of entrance power wire, there should be at least a main 120VAC shut off/circuit breaker (We are talking about 30-amp 120VAC Service – There is 50 amp as well).  Per the NEC there should be a power ground from this this MPOE Breaker panel ground, attached to the vehicles metal frame and skin. Using a minimum of #8 Copper.  This chassis ground is for your safety, as well as those around you.   For fire prevention safety as well as electrocution prevention safety.

The problem with a vehicle, and the electrocution hazard it presents, is due to the rubber tires.  The tires insulate the metal vehicle from having any electrical path to the actual ground you walk around on.  Once you bring AC power on board the vehicle, attached to something like Park Power or Residential Power.  The potential of electrocution is now present.  Should the AC Wiring be wired wrong, or end up with a fault due to vibration, damage, or what have you.  The entire chassis of the vehicle can become electrified.  You would be totally unaware.

 A fault within the vehicle may not trip any breaker.  Especially if there is no “path to ground”.  The metal of your vehicle could become electrified.   Someone walking up on the ground outside.  Then touching the metal of the vehicle.  Their body could provide the electrical conductor between the electrified vehicle and electrical ground potential they are standing on.   Current would flow through their body.  Many conditions like wet ground verses dry ground could make this current flow be anything from a minor shock, to causing death.

There is a section in the NEC (National Electrical Code – USA) that pertains to Recreational Vehicles.  Which explains the requirement of a #8 copper power ground that must be attached to the vehicles metal chassis/skin.   This is an electrical item you don’t want to ignore or omit.

Also a side note.  A defective umbilical having to do with the ground wire, or a defective Park Power receptacle causing no ground.  Has the potential of also electrifying your vehicle if you have a fault in the vehicle.  It is always wise to verify/test your power anytime you connect up to any 120VAC.  There are testers and wazoo devices sold to the RV market just for this purpose. 

Some of these devices are plugged in series with the power umbilical cable.  They have the ability to shut off and not pass power on to your vehicle if there is a fault.
  So with that in mind.  You have to realize this stuff happens often enough, or they wouldn’t be selling these devices.

Whether you use a Converter – Charger that provides a 120VAC “Main” Shutoff/Breaker within it.  Or you decide to use a stand alone 120VAC “Main” Shutoff/Breaker.  Or some other arrangement.  You need to address the power ground that is supposed to be attached to your metal chassis/Skin

Most RV trailers, with one Air Conditioner, commonly operates on the assumption of using at least 30amp service. Via a minimum #10 Three conductor umbilical power cord.

Larger set ups with two Air Conditioners, or vehicles/trailers with heavy power requirements.  Will require 50amp service panels and umbilical power cables rated to handle that load.

The Power ground should also be grounded to the metal vehicle frame and metal skin.  That, as mentioned before should be at the minimal point of entry.

We are only covering the more common 30amp configurations.

What does a Converter-Charger provide?
(Reference the Progressive Dynamics PD4045)

*Main Breaker for the 110VAC main service power umbilical
* Multiple Branch Breakers for 110VAC Trailer circuits (outlets-lights-Air Conditioner) Using GFI breakers as necessary.
* 110VAC Neutral Buss Bar
* 110VAC Ground Buss Bar
* 12VDC Battery (+) Positive side Multiple Fuse distribution panel
* 12VDC Common (-) grounding point to run all 12VDC grounds to
* 12VDC Battery Charger -Smart Charger – Internal Charger Cooling Fan
* Fused Converter-Charger to Battery connection terminal.
* Reversed battery wire polarity protection
* Ground Connection point to ground electrical to metal vehicle frame & skin

When unplugging 110VAC power from a source like Park Power all your 12VDC circuits are still live via your trailer’s 12VDC Auxiliary Battery. No need to remember to flip switches or do manual things to switch over.

Our recommendation is the Progressive Dynamics PD-4045.

There are other configurations that Progressive Dynamics builds in other amp values. There is also another widely used manufacturer, WFCO.  WFCO also builds various units. Both of these manufacturers units are found in the majority of all commercially built RV units.

Be sure the unit you install has a “Smart” charger that outputs the proper charge characteristics. Matched for the specific type of “House” battery bank you intend to charge.  They are not all the same.  Some of the newer models are able to be set or auto-adaptive to “Flooded”, “AGM”, or “Lithium”.  Many of the old models [still out there for sale] are not compatible with “Lithium”.

We like installing parts and components that are easily found both 0n-line, and off the shelf in RV Parts/Suppliers, or even common hardware stores. You never know when you may have to do a replacement during an “on the road” failure. The PD-4045 is widely available on Amazon, at RV dealers, and in stores like Camping World.