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How to Charge a Trailer Battery While Driving [BEST METHOD]

Can’t find enough information on how to charge a trailer battery while driving? Then we got your back. Below, we’ll explore how you can charge your RV when driving down the road and why it’s drawing too much power. This method is easy and time-efficient.

We’ll also cover how you can expand the lifespan of your battery with four simple tips, which you can do at home.

But before getting started, just know that you will need a relay, fuse, and multimeter for this quick job.

Why Your RV is Using Too Much Power

As you might know, your RV trailer has many computerized gadgets and circuit panels.

And while all these features make our lives easier, it comes with a significant downside: it requires a lot of power to work.

For example, even if your stereo is not on, it goes into standby. It never really turns off.

This also holds true for other things like your fridge and water heater. They are all waiting for user input, which, unfortunately, requires a lot of power.

But here’s the thing: your battery is never supposed to drop below 50%. So every time it goes below this interval, you’re reducing its lifespan.

Typically, your battery should last 8 to 10 years—depending on how well you take care of it. But with this constant loss in power, you might not get close to that interval.

How to Expand the Lifespan Of Your Battery

Understanding how to charge a trailer battery at home is a crucial skill to have under the belt, but it doesn’t help much if you don’t know how to take care of your trailer’s battery.

So, here’s some advice to preserve your battery:

Disconnect The Battery Terminals

We get it asked all the time. Can’t I just unplug my battery switch and call it a day? Well, it doesn’t fix our problem.

Sure, this switch is meant to cut off the power, but there’s still something drawing off your power.

So, it’s not really useful, and you’re still lowering the lifespan of your battery.

Instead, disconnect the battery terminals from the wires of the RV. This will stop any unintended parasitic load.

Don’t let it Drop Below 50%

Always monitor your battery’s charge and make sure it never goes below 50%. Like we noted before, going below this number will destroy the lifespan of your battery.

This can get worse if you keep on using the battery after it drops below %50. It might not hurt if it’s just a one-time thing.

Just make sure to keep an eye on your battery if you want to get the most out of it.

Keep an Eye On Your Battery

Batteries go out all the time. They are not bulletproof. So, it is in your best interest to make sure that your battery is always in great shape.

Look for any signs of corrosion or damage around the battery. If you suspect that there’s something wrong with it, replace the battery.

But if you don’t feel confident about your skills, take the battery to a professional and have it tested at least twice per year.

Store Your Battery

If you don’t plan on driving your RV for the next six months, professionals recommend removing the battery from the vehicle and storing it in a cool, dry place.

If you go with this method, get a battery maintainer, and you should be good to go.

But don’t get too far ahead just yet. By all means, avoid putting your battery in your living room since it could affect your health. Instead, we suggest putting it inside your garage.

If you need more information about preserving your trailer’s battery, here’s a video with several tips:

5 Signs Your RV Battery is About to Die

It would help to know whether your battery is working or not, along with how to charge a travel trailer battery.

That said, here are common signs to tell if your battery is not working:

Cooling Fan And Internal Vents Are Not Working

Having problems with your cooling fan? Then it means there’s something wrong with your trailer’s battery.

Your RV uses the battery to power everything inside. So, if it doesn’t have any power, your equipment won’t work.

Lights Keep Blinking

Noticed that your lights won’t stop flickering? Then your culprit could be the battery. First, inspect the battery and make sure it didn’t get corroded.

Second, grab a multimeter and make sure you’re getting the correct voltage. Batteries go out all the time. So it wouldn’t be far-fetched.

Battery Won’t Hold a Charge

Another common way to tell if the battery is not working is whether your battery can hold a charge or not.

For example, if you’re trying to jump-start your vehicle and noticed it wouldn’t start up no matter how many times you try, it means that there’s a problem with the battery.

Corrosion

Popped the hood of your trailer and couldn’t help but notice that the terminals around the battery got corroded?

Well, you’re not alone here. Unfortunately, this is pretty common, but it doesn’t always mean that the battery got damaged.

In fact, you might be able to start the trailer if you cleaned off all this gunk around the terminals.

To do this, get some sandpaper and rub it against the terminals. Remove all the corrosion and clean off any residue.

Swollen Battery Case

The fifth symptom is a swollen battery case. Your battery case should never swell up.

That said, if you noticed that your battery is no longer flat and nice, you have to replace it as soon as possible. There’s nothing you can do to bring it back to life.

How Often Should You Charge an RV Battery?

We tell drivers to disconnect the battery to prevent parasitic losses and then charge the battery as they need.

This is the most effective and cheap method to protect your battery for as long as possible.

But if that’s not an option, we’d say that you should charge your battery once a month. Don’t let it go below 50% charge, and you shouldn’t have any problems.

Then again, it would make more sense to remove the battery from the RV and store it somewhere cool dry.

Why Your Battery Is Taking Too Much Time to Charge

We’ve seen many drivers assume that their batteries are dead just because they take too long to charge.

Don’t worry, though. We’ve been there before and know pretty well it’s easy to assume all those things.

However, RV batteries take a lot of time to charge. It’s not like you can fully charge your battery as you’re driving.

Even if you drive for the next 4 hours non-stop, it won’t charge your battery completely.

RV batteries can take up to 24 to 48 hours. So, yeah, there’s nothing wrong with your battery. It just needs a lot of time to get to that point.

How to Charge Your RV Battery While Driving

Noticed that there’s no 12V power going to the 7-pin? There is a simple fix to this problem, which is to use a fuse and relay. That said, here’s how to charge a trailer battery from truck:

1. What You Will Need

This job does not take more than 5 minutes, and the only tool we need is a multimeter to test whether we’re getting 12 volts or not.

2. Check Your Glove

You should find a relay and a 30-amp fuse in your glove box, which you need to get power to the 7-way pin. That way, you can charge your trailer while driving.

3. Install The Fuse & Relay

First, check your owner’s manual to install the fuse and relay properly. That being said, put the hood of your truck and then open the fuse box.

After that, install the fuse and relay according to your owner’s manual.

4. Start The Car

Here’s how to charge a trailer battery with tow vehicle: have your key in the on position after installing the fuse and relay.

Next, take your multimeter red lead and put it where it says “VΩ,” then plug the black lead where it says “COM.”

And finally, put the multimeter on volts DC. Be careful, though. Do not put the meter on AC. We need volts DC to test the power we’re getting.

5. Test Your 7-pin & Make Sure You’re Getting Power

Put the red and black leads inside the 7-way pin. The multimeter should now display the voltage on the screen.

If you’re getting 12 volts, then it means you’ve successfully installed the fuse and relay.

Now you should be able to charge your trailer while driving.

How to Charge Your Trailer’s Battery With a Generator

Yes, you can charge your trailer’s battery with a generator. It is easy, and anybody can do it with the right tools. So, here’s how to charge travel trailer battery with generator:

1. Be Sure That Your Generator Has Enough Power

To start, please make sure that your generator has enough power. Otherwise, you might spend unnecessary time troubleshooting to find the culprit.

2. Turn off the Trailer

Now turn off your RV, and then unplug everything inside the trailer. This way, it won’t take as much time to charge the battery.

Think of it like your smartphone. You wouldn’t use it while it’s charging.

3. Disconnect the Battery

First, start by disconnecting the negative terminal from the battery and then disconnect the red terminal.

4. Carefully Inspect Your Battery

Check your battery to make sure it is free of corrosion. If there’s gunk around it, try cleaning off any dirt you see around the battery.

Your battery should be in usable condition before charging it. After cleaning the battery, plug back the terminals.

5. Connect the Trailer Cables to Charge Your Battery

How to charge a battery on a trailer: Connect your trailer plugs to the generator. The battery should be charging now.

Keep an eye on it and make sure it does not overcharge.

If you’re having a hard time following along, here’s a short video you can watch:

Frequently Asked Questions (FAQs)

We know it can be daunting to find any information on how to charge a trailer battery while driving.

So, here are common questions we’ve been asked before, which you might find to be helpful:

Can I charge my RV battery with jumper cables?

Yes, you can charge your RV battery with jumper cables. If you don’t have any jumper cables, it might be time to get a set. You never know when you might need them.

How do I know if my deep cycle battery is bad?

If you have broken terminals, there’s a high chance your trailer’s battery is bad.

But in other cases, your battery could have a bump, which means that your battery is not working anymore and must be replaced.

Does a 7 pin trailer plug charge battery?

Yes! Your 7-pin trailer plug charges your battery. However, keep in mind that it only does so when the key is on the “on” position.

Can you charge an RV battery with a generator?

Yes, you can charge your RV battery with a generator. It is not the safest method for charging your battery, but it is pretty helpful if you can’t charge the battery while towing.

Conclusion

It barely takes any time to learn how to charge a trailer battery while driving.

However, it can get a little bit tricky when you have to run several cables to charge your RV trailer as you’re going down the road.

Instead, we kept it as simple as possible. We need simple tools that you should have in your glove box.

But remember, there are several ways to expand the lifespan of your battery, such as disconnecting the battery when you’re not driving and storing it in a cool, dry place.

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