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Electrical Systems in an RV

There are many ways to do something right, including installing or upgrading the deep cycle batteries in your RV. Each battery installation method has pros and cons but we will try to explain several. This page is designed to show you a few of the ways secondary deep cycle RV batteries are installed in a motor vehicle and isolated from the engine starting system so you don't drain the starting batteries. This is in no way a complete manual, as such, an expert mechanic should be consulted on all upgrades and repairs.

Let's get started; First there are battery chargers and there are battery voltage regulators. Each does the same thing, they are designed to charge a battery. The difference is in the type of input electricity. Battery chargers run on AC electricity.(Grid or Generator) Battery voltage regulators or battery charge controllers run on DC electricity. (Solar, Hydro, Wind, Generator, Etc.) Other than the input, they are fairly similar. These are the items that CAN control battery charging.

To illustrate the whole picture we are going to go over battery chargers, and the types available as we go. This will both educate you to the applications of chargers and charges on batteries, as well as help to integrate multiple systems into your RV, Coach, or Motor home.

So if battery chargers and charge regulators do the same thing, how do they do it?

Well there are basically 3 ways to charge a battery. There are hundreds of variations on these 3 types of charging algoryhtyms, but by in large, these methods cover the majority of publicly available battery chargers on the market today.

Generally the three types of battery chargers fall into these categories:
  • 1 Stage Battery Chargers and Battery Voltage Regulators -
    Continuous Bulk Charging
    Simply hook up power to a battery and never control it.
    Equivalent of a solar panel or alternator directly connected to the battery, think of cookies or a turkey in the oven forever, they dry out. Constant Current and Constant Amperage
  • 2 Stage Battery Chargers and Battery Voltage Regulators -
    Bulk Stage Battery Charging and Float Stage Battery Charging Programs for batteries always under load. 2 stage chargers are not tricked into overcharging batteries that are being used while they are being charged. Some high quality 3 stage chargers, yes the expensive ones, can ``sense`` batteries under load. These chargers then switch into 2 stage charging mode automatically to protect the batteries.

    Variable Current and/or Variable Amperage, charging curve varies by manufacturer
  • 3 Stage Battery Chargers and Battery Voltage Regulators -
    Bulk Stage Battery Charging, Absorption Stage Battery Charging, and Float Stage Battery Charging Programs,

    A three stage charger is usually regarded as the the best type of charger as it can ``top off`` or completely charge a battery more quickly than a 2 stage charger. However, if the battery bank is under load while under the ``absorption`` stage of charging, routinely, the batteries are overcharged. Therefore the three stage battery charger or charge controller is the cream of the crop ONLY if it is built by one of the reputable manufacturers, and it can jump into 2 stage mode to protect batteries under load.

    Variable Current and/or Variable Amperage

  • Power Blocking, Protecting the Starting Batteries

    There are generally several well regarded installation methods for secondary deep cycle battery banks in motor vehicles, RVs, coaches, and motor homes. The first order of business is to separate the motor starting batteries from the house bank of batteries. Nobody likes to run down the RV batteries, but it is worse when you killed the starter battery, and you are stuck in the wilderness.

    Generally there are 2 methods for isolating the secondary battery bank from the engine starting bank of batteries; Diodes and Solenoids.

    Diodes are one way doors for electricity, and come in many shapes and sizes. Long story short, you can buy these in two varieties for this application, you need 2 loose diodes, or a battery isolator that comes with 2 schottkey diodes built inside of a heatsink that is easily mountable. Pictures of both are below, click on them to go to pages where you can purchase these items.
    blocking diodes 200 volt, 85 amp
    Blocking Diodes
    battery isolator with 2 schottkey diodes 24 volt, 100 amp
    Battery Isolator
    w/ Schottkey Diodes

    Solenoids are a door for electricity that is controlled by an electrical switch. For instance many have wired their RVs and Campers directly to the ignition, so without the key, there is no connection between the starting battery and the deep cycle batteries. You will see this below as the first electrical schematic. However, if you wired your ignition as the positive ``switch`` leg for a solenoid, and had a line running from the alternator to the battery through the solenoid, the ignition controls when the batteries start charging with the engine system. However, this isn't ideal.
    How do you ``stop`` charging the batteries?
    With ``FAST CHARGING BATTERIES`` can I knock out my starting battery as soon as I turn the switch?
    Can I super charge the batteries instead of starting the truck?

    Installation and Electrical Schematics

    Here are two schematics for RV Battery installations.
    1 stage battery charging electrical installation schematic for a RV
    2 or 3 stage battery charging electrical installation schematic for a RV

    battery charge controllers and DC battery ChargersAs you can see, the proper way to install a charging system in a mobile vehicle involves 2 pieces.

    1. A battery isolator (or 2 diodes)
    2. A battery charge controller so you don't cook your batteries as you drive long distances.......

    Charge controllers come in various sizes, click here for some economical DC charge controller and DC Battery Charger options


    If you already have installed the battery charge controllers, and you know build in a disconnect from the engine bay, it is very easy to use the same charge controllers to control temporary solar panel arrays, wind generators, or other temporary power supply sytems in your campsite. These renewable energy sources can be routed through the existing charge controllers, safely into your expensive battery banks.

    RVs or Pushers with All In One Charge/Inverter/Controllers

    2 or 3 stage battery charging and AC inverter electrical installation schematic for a RVThis schematic shows how a 3 stage charge controller that is also a inverter fits into this mix. Notice that the inverter doesn't move from the charge controller installation above.

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