Guide To Installing An Auxiliary Battery For Your Camper

If you're looking to hook up an auxiliary battery to your camper, you've got a few options. You can either install a dual-battery setup, which involves connecting two car batteries to your vehicle's alternator and adding an isolator to keep the batteries separate, or you can use an auxiliary battery charger, such as a solar panel setup.

For a dual-battery setup, you'll need to purchase a second battery, an isolator, and any necessary wiring and accessories. This option allows you to charge both batteries while driving, but when the vehicle is off, the batteries are separate and you can use the secondary battery for your accessories and electronics without worrying about draining your main battery.

If you're looking for a standalone solution, you can consider installing a solar panel system to charge your auxiliary battery. This option is great if you plan on camping off-grid and won't have access to AC power for extended periods.

Either way, it's recommended to consult with professionals, such as car stereo specialists or RV repair shops, to ensure a proper installation that meets your specific needs.

Using a Hopkins adaptor to connect the auxiliary battery to the camper

To connect an auxiliary battery to a camper, you can use the Hopkins # HM47210 adaptor. This adaptor is suitable for a 7-way blade type plug and can send 12-volt power through the auxiliary.

To install the Hopkins adaptor, first, ground the white wire to a clean, bare-metal surface on your trailer. Then, run some 10-gauge wire from the red wire on the connector to your battery. This method is not as clean as hardwiring your battery into the 12V power circuit on your trailer, but it will allow you to draw power from your battery without connecting the 7-way on your trailer to anything else.

When you need to use power, your auxiliary battery will be ready to go. To keep your battery charged, you can use the CTEK MULTI US 4.3 Universal 12-Volt Battery Charger when you have access to AC power. If you are camping off-grid and do not have access to AC power for long periods, you can install the Redarc BCDC Battery Charger and use a solar panel to slowly charge your battery.

Installing a dual battery setup

A dual battery setup is a great way to ensure you have enough power for your gadgets and appliances when camping, without risking not being able to start your vehicle engine.

Choosing a dual battery

There are four main types of deep cycle battery suitable for a dual battery setup:

• Wet cell: These are of similar construction to your existing car battery and are designed to supply power for longer. Wet cell batteries are suitable only for under bonnet installation.
• Gel batteries: These are less commonly used and can be installed under the bonnet or in the cabin.
• AGM batteries: Similar to gel batteries but must be installed away from the intense heat of the engine bay.
• Lithium: Lithium batteries are half the weight and double the power of the other options. They are more expensive and require a lithium-capable charger.

Choosing the correct cable

A DC battery charger draws a lot of power to top up your dual battery. To combat 'voltage drop', which causes power loss the further you get from the main vehicle battery, you need to use the correct thickness of the cable. The thickness depends on the amps of your DC charger and the length of the cable required.

Mounting a second battery

You'll need to find a spot to mount your second battery that is out of the way, protected, and with enough space to secure it firmly. Battery boxes are a good option as they provide protection and come with handy power outlets.

Mounting a DC charger

When mounting your DC charger, consider ventilation as it can get quite warm. Find a flat mounting surface where it won't be smothered or knocked, and ensure it's close to your dual battery to lessen voltage drop.

Circuit breakers

Circuit breakers are important for safety. In the event of something going wrong in your dual battery system, a circuit breaker will cut the power to prevent a fire. You need one circuit breaker for each battery, located within 15cm, and as close to the main battery as possible.

Wiring a dual battery system

• Disconnect the negative terminal of your battery.
• Measure and cut a length of heavy-duty cable from the positive terminal to the circuit breaker. Attach a lug to each end, then fit a length of corrugated tube and heat shrink.
• Leave this disconnected from the battery and use cable ties to run it to the circuit breaker.
• Fit a terminal, tubing, and heat shrink to the remaining cable and fix it to the circuit breaker.
• Follow existing wiring looms towards the nearest firewall grommet, using cable ties as you go.
• Push a wire through the firewall grommet. This can be tricky, so go for the largest, most accessible grommet. You may need to cut a small slit or use a stiff wire to poke through.
• Whichever method you choose, be careful not to damage existing wires and leave a drip loop outside the grommet to prevent water from entering.

Workarounds for smart alternators

Smart alternators vary their voltage output to suit conditions, which can affect charging your second battery. A DC charger can compensate for this, but to prevent draining your main battery, you'll need to connect a trigger wire to an ignition power source.

Finding an ignition power source

Look for ignition power underneath the steering wheel around the pedals. With the ignition on, use a test light to back probe electrical plugs until the lamp illuminates. Solder your wire into this.

Wiring a DC charger

• Route the power cable and ignition trigger wire to your DC charger.
• Cut off any excess cable and finish with a crimp terminal.
• Grab a short length of black cable and fix the other crimp terminal to one end. Both this and the power cable can be joined to the DC input plug on your charger.
• Attach the other end of the black cable to a nearby bolt to earth it to the car body or chassis.
• If you have an ignition wire, cut and solder this to the trigger wire on your charger.
• Grab a short power lead with 50-amp connectors and connect one end to your battery box and the other to the output from your DC charger.

Testing a dual battery system

• Make the final connections under the bonnet by attaching the power cable to your positive terminal and reconnecting the negative terminal.
• Set the battery type on your charger.
• Turn the key in the ignition. The charging lamp on your DC charger should illuminate.
• Probe a power outlet with a multimeter to check the charge voltage.
• To check the charging current, hold a clamp meter around the positive or negative cable on your DC charger output cable.

Now you're ready to enjoy your camping trip with plenty of power!

Using a battery isolator to keep batteries separate

A battery isolator combines the 'house' battery bank that powers your lights, fans, refrigerator, and other appliances with your starting battery, allowing it to be charged by your vehicle's alternator. This setup is simple to install and provides peace of mind, knowing that you won't drain your main battery while using your camper's electrical system.

When choosing a battery isolator, it's important to consider the amp rating, which represents the maximum possible amps that can pass through the component from your alternator to your home battery bank. The size of your battery isolator will depend on the size of your alternator, as you'll want to manage the maximum amp output. You can usually find this information in your vehicle's spec sheet or stamped on a metal plate on the alternator itself.

Additionally, if you're using lithium batteries, it's recommended to use a lithium battery-specific isolator due to their resting voltage rates. Standard isolators may not disconnect properly when the engine is off, as they may interpret the higher voltage of lithium batteries as 'charging'.

When installing a battery isolator, it's important to use the appropriate wire gauge and length to ensure optimal performance and safety. It's recommended to use 2/0 wire, which is suitable for most applications and can handle high currents. Proper fusing and circuit protection are also crucial to ensure the safety and longevity of your electrical system.

By following these guidelines and consulting with professionals, you can confidently install a battery isolator in your camper, keeping your batteries separate and ensuring a reliable power source for your adventures.

Charging the auxiliary battery using solar panels

Solar panels are a great way to charge your auxiliary battery, especially if you are camping off-grid and don't have access to AC power. They are also a good option if you want to keep your campervan battery charged while it is in storage.

Solar panels can be installed on the roof of your campervan or motorhome, and they charge the auxiliary battery by converting sunlight into electrical energy. This setup is known as a solar-powered system.

Types of Solar Panels

There are different types of solar panels available, and the most common ones are rigid panels and flexible panels. Rigid panels are typically made of crystalline silicon, while flexible panels are made of thin-film materials. Flexible panels are lightweight and designed for curved rooflines, making them a good option for campervans.

Sizing Your Solar Panel System

When sizing your solar panel system, it is crucial to consider your energy needs. Calculate your power requirements by adding up the amperage ratings of all the appliances you plan to run. This includes items such as lights, water pumps, refrigerators, and entertainment systems.

Number of Solar Panels

The number of solar panels you need depends on the wattage of each panel and the square footage of your campervan roof. Most campervans use 100-watt to 200-watt panels due to roof size limitations. However, if you have a larger roof or higher energy demands, you may need to install multiple panels.

Solar Charge Controller

A solar charge controller is a vital component in your solar-powered system. It regulates the charge going into the auxiliary battery and prevents overcharging. When choosing a solar charge controller, consider the type and size of your battery bank and the output of your solar panels.

Installation and Orientation

Proper installation and orientation of solar panels are critical for maximizing their efficiency. Solar panels should be installed securely and angled to capture maximum sunlight. They should also be periodically adjusted to follow the sun's path for optimal performance.

Maintenance and Care

Solar panels generally require little maintenance, but it is important to keep them clean and free of debris. Regularly inspect and clean the panels to remove dust, leaves, or other obstructions that may reduce their efficiency.

Combining Solar with Other Charging Methods

For extended off-grid camping or periods of low sunlight, you may consider combining solar power with other charging methods. This could include using a vehicle alternator to charge the auxiliary battery while driving or utilizing a battery charger or shore power when available.

Safety Considerations

Always prioritize safety when working with electrical systems. Ensure proper ventilation during installation to prevent the buildup of explosive gases. Securely mount the solar panels and battery to prevent movement during travel.

By following these guidelines and considerations, you can effectively charge your auxiliary battery using solar panels, ensuring a reliable power source for your campervan or motorhome.

Using a battery separator to keep the truck and camper batteries separate

When it comes to keeping your truck and camper batteries separate, a battery separator is an excellent solution. This device allows you to connect two batteries to your vehicle's alternator while ensuring they remain isolated. This means that when your truck is turned off, the batteries are not connected and cannot drain each other.

There are a few different types of battery separators you can choose from:

• A continuous duty solenoid: This is a simple and cost-effective option that can be triggered by your truck's ignition. It's important to control the solenoid with the truck's switched circuit to ensure effective separation.
• A diode-based battery separator: This type of separator induces a voltage drop in the circuit, which can affect charging performance. The drop is typically about 0.7 volts per diode.
• A voltage-sensing relay (VSR): This electronic circuit closes a relay when the truck's input voltage exceeds a certain level, resulting in no voltage drop in the charge circuit.
• A battery isolator: This option is ideal for truck campers as it allows you to connect your camper and leave it plugged in without worrying about draining your main battery. It's important to mount the isolator under the hood of the truck for optimal performance.

When installing a battery separator, it's crucial to use appropriate wiring. For example, a Dodge Ram with a factory trailer harness uses a 14 AWG wire, which may not provide sufficient charge rates. In this case, upgrading to an 8 AWG wire for a minimum of 20 feet is recommended. Additionally, ensure that you locate the circuit protection closest to the battery ends for the best protection.

By using a battery separator, you can keep your truck and camper batteries separate, ensuring that your truck battery doesn't drain while your camper is plugged in. This simple yet effective solution provides peace of mind and helps you maintain adequate charge in both batteries.

Frequently asked questions