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Does Your Truck Charge Your RV’s Battery?

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Will your truck charge your RV’s battery while driving down the road?  Your tow vehicle will charge your RV while you are driving down the road, but this doesn’t tell the whole story.  While your tow vehicle will provide power to your camper, it may not be enough to power all your 12V DC appliances or charge an extremely low battery.

There are ways to get more power to your camper, but they require additional equipment to be installed.  Let’s take a look at how your truck generates power and how it gets to your camper.

How your tow vehicle’s charging system works

All vehicles use an alternator to charge the battery.  Like most things in your vehicle the charging system is computer controlled.  The level of your truck’s battery and the electrical draw of the vehicle are used to control the voltage output of the alternator.  This system works great for maintaining the correct charge on your truck’s battery.   When your vehicle’s battery is low the system increases the voltage allowing more power to flow into the battery charging it up.  Once the battery is fully charged the voltage is lowered and only stays high enough to keep everything operating.

While your trailer is connected is receives 12V DC power from the trailer wiring harness.  This power can run your fridge, lights, or anything else in your camper.  The problem is that your vehicle doesn’t know there’s a battery in your camper that needs to be charged too.  Once your vehicles battery is sufficiently charged, the voltage output from the alternator will be reduced and will provide very little current to your camper.  If your vehicle is connected and running for a long enough time it would eventually charge the battery up, but this is more like a trickle charger.

How can you use your tow vehicle to “Charge” your RV’s Battery?

If you plan on being “off grid” for extended periods of time and want to used your vehicle to charge your camper’s battery it can be done with a little wiring and a Battery to Battery (B2B) Charger.

You install a B2B charger in your camper near the battery.  It connects between your RV and Truck batteries.  The B2B charger will make your truck think its battery still needs to be charged keeping your alternator outputting a higher voltage.  The B2B charger transfers that additional energy to your RVs battery instead.

An added bonus of using a B2B charger is that most have a Dual Inputs meaning your can add a second power source like solar panels to charge your batteries too.

B2B chargers are rated for different amperages, the higher the amps the larger size wire you will have to run to the charger.  When using a B2B charger you will have to add an additional connection between your truck and camper to transfer that power, the small wires in your trailer harness can’t handle the higher amperage.

Here is a link to Redarc 25A charger this should be plenty for most applications with a single or dual battery RV.

Other Charging Options

Like we have already discussed, your standard trailer connection will provide some power to your RV, but if you need additional charging and don’t want to install a Battery to Battery charger you do have some other options.  The AC to DC converter built into your RV will charge the battery any time you are connected to 120V power, so if you can find somewhere to plug-in for a while you can charge your batteries that way.

Use a Generator to charge your RV’s Batteries

If you don’t want to run your AC or microwave a small generator around 2000 watts is easy to put in the bed of your truck and will provide plenty of power to top off your battery and extend your “off-grid” camping.  The downside is that you will also need to carry fuel for the generator.  An inverter model like this one from WEN will be much quieter than a traditional generator.

Add Solar Panels to Charge your RV’s Batteries

Although the B2B charger will allow you to install solar panels a dedicated solar charger will help you make the most of the Sun’s rays.  This is one of the best options for extended trips away from power.  With enough solar you could keep your RV powered for as long as you want.  Here is a great guide to installing solar power on your RV.

Wrap Up

Hopefully now you understand the limitations of charging your camper from your tow vehicle.  If you still have any questions or would like to share your experience, please leave a comment below.

Thanks for reading and Happy Camping,