Charging Trailer Battery from Tow Vehicle

Power considerations are top of mind when towing a camper or trailer. Charging a trailer battery from a tow vehicle is one way to ensure your RV’s 12-volt battery pack never runs too low.

How to charge trailer battery from a truck? Is it possible? Sure!

Charging camper or trailer batteries while towing is no problem. However, you either need special equipment to do it, or it’ll already be present and it’s necessary to understand how to use it.

Understanding Your Camper Trailer Battery Charging System

With the camper trailer battery charging system, it’s possible to hook it directly up to the electricity at home or in an RV campground.

At home, it’s either a 15- or 20-amp system. The RV park uses either 30 or 50 amps.

Hooking up your camper or trailer to charge the batteries at home or on a campground is an excellent idea. This is because deep cycle batteries can suffer when their retained charge falls below 70% or so, with a significant chance of battery damage below 50%.

Therefore, take every opportunity to keep all batteries topped up.

However, when that’s not enough, then you’ll need to keep charging the house batteries while driving too. This won’t happen automatically unless you’re equipped to do so.

Read Also: How to Watch TV with a Generator

How to Charge an RV Battery from a Vehicle

Charging Camper Battery from Tow Vehicle

Charging your camper battery with a tow vehicle isn’t that difficult. However, you will need the proper equipment to do so.

If you’re charging a trailer battery while towing, then it may already have a universal mount or switch insert added near the hitch at the rear. Otherwise, this will need to be fitted for you.

The idea behind supplying power to a camper being towed is it enables various systems like the brakes, lights, and turn indicators to function.

This way, while the camper blocks the rear view of the tow vehicle for other drivers, nearly identical reversing, braking, and other light indicators are displayed on the towed vehicle instead.

Read Also: Towing a Travel Trailer in High Winds

Charging Trailer Battery from Tow Vehicle: Is it Any Different?

With trailer battery charging, it shouldn’t be any different from charging a teardrop camper (or another type).

It’s the same systems, and the same equipment too. Therefore, to charge trailer battery while driving is no more complicated.

Does travel trailer battery charge while towing?

A trailer battery charger is required to ensure power sent and received does charge the house batteries while on the road.

At least, a 7-pin plug setup is necessary to do so and is covered in detail below…

Read Also: Fastest Way to Charge RV Batteries?

How to Charge a Trailer Battery While Driving

The trailer (or camper) needs a 7-pin plug (sometimes referred to as a 7-way). The plug connects your truck to the trailer or camper.

Either you’ll need to purchase the equipment necessary to charge via a 7-pin plug using your truck or car as a towing vehicle or have a specialist fit it.

Read Also: How to Charge RV Battery with Generator

Charging Trailer Battery from 7 Pin

The 7 pin plug is designed to facilitate pass-through energy onto the towable’s systems.

Not only does it supply power for charging the house batteries in the camper or trailer, but it also does other things too.

Each of the 7 pins inside the plug provides a different facility that’s distinct from each other. Here is a breakdown list:

  • Tail and running lights
  • 12V power
  • Reverse lights
  • Right turn and stop
  • Left turn and stop
  • Brake controller output
  • Ground

Through the 7-pin system, various lights on the rear of the towable are managed to ensure that when you brake, the brake light illuminates the rear of the trailer or camper for other drivers to see.

Similarly, the brakes are activated via the brake controller output system.

On the power side, 12-volt power is fed through from the truck to the trailer or camper. The charge is received by the house batteries topping them up while underway.

Read Also: How to Tell If a Deep Cycle Battery is Bad

What is the Difference Between 7 pin and 13 pin Electrics?

You may have seen mention of a 13-pin electric connection too. Here we cover the differences:

7 pin Electrics

There are several different 7-pin systems to supply power, light signals, and more to the towable.

Some are used for commercial or haulage purposes, whereas another relates only to RVs and towing your camper or trailer behind you. We’re only concerned with the RV type.

13 pin Electrics

13-pin electric connections are far less commonplace. These are similar to 7-pin, but provide an extended list of facilities for the camper or trailer to use.

Just like the 7-pin includes brakes, lights, and 12-volt power, the 13-pin goes beyond that.

There are even 13-pin to 7-pin conversion kits if you need 7-pin and your current system is 13-pin. Fortunately, most RVers can easily access the 7-pin RV systems which are fairly universal now.

A truck towing a camper/trailer behind on sand

Read Also: How Long Will A 12 Volt Battery Run a Refrigerator?

DC to DC Chargers to Charge the Camper or Trailer

While charging from the towing vehicle to the camper or trailer while driving works fine, it usually only trickle charges the battery.

Also, it mostly works when driving, unless you’re planning to run your engine while immobile, which isn’t the best idea.

Charge Faster and Be Ready for Dispersed Camping

Once you’ve arrived at your destination, it’s beneficial to use a DC to DC charger to boost your battery up to a satisfactory voltage level.

DC-to-DC charging systems are designed to supply an electric current either from solar panels directly or from the tow vehicle’s battery. Using this system works faster than relying on the alternator and has other advantages too.

If you’re at a campground and on a pitch with electrical hookups, simply plug into the 30-amp or 50-amp power to charge your towable’s batteries.

However, you may have a camping spot that isn’t supported by hook-ups or be dry camping on BLM land.

If so, ensure your camper or trailer batteries are fully charged. Otherwise, charge them up pronto! This is where DC to DC chargers come in.

Using the Correct DC to DC Charger Type

With a DC-to-DC charger, ensure it’s compatible with your battery type.

Depending on whether you’ve got gel, lead-acid, AGM, lithium, or another type, pick appropriately and bear this in mind when replacing the batteries later too.

Redarc BCDC Battery chargers come with dual inputs and handle 12-volt power. They’re a robust solution and have products supporting charging from solar panels or the vehicle’s battery.

These products may support 12-volt and 24-volt for a towable with greater power requirements, as well as support for different amperage levels (12, 20, 25, 40, or 50 amps) depending on your needs.

Choose these types of products carefully to ensure they’ll deliver the service needed once at a campground or when dispersed camping.

Redarc Dual Input 50A in-Vehicle DC Battery Charger

Check at Amazon

ⓘ If you click this link and make a purchase, we earn a commission at no additional cost to you.

Closing Thoughts

Keeping your house batteries topped up is essential. Otherwise, you risk arriving at your destination and discovering that your camper is without power.

Also, once most battery types (except lithium) fall below a 50% charge, their failing performance will be evident. Should that happen, they’ll all need replacing at considerable expense.

Charging your house batteries while towing the trailer or camper is a great way to keep batteries charged. Adding a DC to DC charging capability also ensures any shortfall in battery levels has a quick fix soon after arriving. That way, you’re covered in either situation.

Related Articles