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Black portable RV generator

Boondocking in the snowy mountains is one of my favorite things to do. 

But it’s not so fun when you run out of power!

This winter, I was in the French Alps when my leisure batteries went flat, so I was in total darkness starting at 4 pm each evening! I tried lighting candles, but I could barely see my hand in front of my face, let alone read a book.

With no electricity for heating, I could hear my teeth chattering all night. Finally, after a week of cold and darkness, I gave up and headed back to town. 

If you want to avoid wearing your hat and gloves in bed and getting bored out of your mind in the evenings, you can bring along a generator for emergency charge-ups. 

So, what size generator do you need for RV batteries?

I recommend a generator with a minimum of 3500 watts and 8 amp power to charge your 12-volt RV battery. Your battery will charge a bit faster if you get a more powerful generator, but you should be OK with 3500 watts.

The Benefits of a Generator for Your RV

The main reason you’d want to charge your RV with a generator is if you’re not going to connect to mains electricity for an extended period. 

Imagine you’re heading out on an extended trip in a national park where you won’t have access to a hookup. With a generator, you’ll be able to recharge your leisure batteries anywhere. 

Generators are also a good option if you’re planning to go off-grid and if you’re living in your RV while you sort out your long-term accommodation. 

Be careful, though. Gennies can be heavy and bulky, so you’ll probably want to look into getting a portable one if you’re taking it on your next road trip. 

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It’s worth noting that even portable generators are a good 100 pounds (over 46 kilos), so don’t expect to find something compact and easy to move around. 

The Drawbacks of a Generator for Your RV

A decent generator can be expensive. They aren’t as efficient at charging batteries as mains electricity, and they are pretty noisy, too. 

I hate it when I drive into the middle of nowhere to enjoy the wilderness, and then an RV rocks up and starts a noisy generator.

All the wildlife gets scared off, and my ‘peaceful’ camping night is ruined. 

So, if you are using a generator (especially considering that they take so long to charge your batteries), please be mindful of other campers around you.

Try to park at a reasonable distance from other vehicles, and don’t use a generator at night when people are trying to sleep!

Gel Versus Lithium Batteries 

The type of battery in your RV is just as important as the generator you charge them with.

Here’s what you should know about the two main types that people use in RVs. 

Gel batteries are much more affordable than lithium batteries. (I’m talking around $300 for a decent gel battery and about $1800 for a ‘low-budget’ lithium battery!)

However, gel batteries are less efficient than lithium batteries in the long run, and you shouldn’t let gel batteries fall over 50% below full power before charging them again. If you do let your gel battery go flat, you’ll notice that it immediately stops holding a good charge. 

You’ll be able to boondock a lot longer with lithium batteries, and you won’t have to replace them as often. Yet, the price difference is prohibitive, so the best choice depends on your budget!

Charging Time

Make sure to leave plenty of time to charge your RV batteries with a generator. 

You’ll probably need up to 10 hours for charging if your leisure battery is nearly flat, so you don’t want to leave it too long and then go without power for the day. 

It can take less time than this; it depends on how effective your generator is and how flat your batteries are. 

By the way, you’ll probably find that your battery charges much efficiently when it’s completely drained rather than when it's still holding power.

But remember to not let your gel batteries drain because they’ll be less efficient after that, and you’ll notice them charging down a lot more quickly. 

Generator Fuel

Generators can be fueled by gasoline, diesel, propane, natural gas, or solar energy. You can also get models that switch between different fuel types. 

The most common and affordable type of generator is gas-fueled. 

Starting Your Generator

Generators can have either a manual or an electric starter. 

An electric starter is more expensive, but all you have to do is flick a switch. A manual starter involves pulling a cord, which can be challenging for people with limited upper body strength. 

Most people should be able to start the generator with the pull cord, so I don’t think the electric switch is really worth it. Besides, almost everything is automated these days, so it can be nice to actually use your body once in a while!

How to Charge an RV Battery With a Generator 

If you’ve never charged your battery with a generator before, here are the three key stages. (Sorry if this seems condescending, but I had no idea what I was doing when I started RVing!)

  1. Make sure your gennie contains plenty of fuel and oil.
  2. Turn off all electrical appliances in your RV to speed up the charging process.
  3. Hook up the generator to the battery and power up the generator.

Safety Tips (for you and your batteries!)

To avoid wrecking your batteries or hurting yourself, here are a few things to keep in mind:

  1. Give your battery a good check-over before charging it. This should include checking for rust and making sure the electrolytes are at the right level. (Before messing around with the battery, disconnect it from any external power source and then remove the black wire followed by the red wire.)
  2. If you find any dirt or rust on the wires, clean it with an old toothbrush and some baking soda, but wipe everything dry before connecting the wires back up. 
  3. Make sure you’ve connected the red and black wire leads into the right places. Otherwise, you will wreak havoc with your electrical system. (In the eloquent words of my husband, something will explode somewhere.)
  4. If your batteries get too cold, they will discharge much more quickly, so you might find yourself caught without power, even if you aren’t using them. (Remember that nightmare trip of mine in the French Alps? I certainly do!)
  5. Don’t touch the battery or any cables while the generator is charging them. (Take off any metal jewelry, too!)

Final Thoughts 

A portable generator can be a neat way to keep your leisure batteries charged while you’re on the move.

You’ll want at least 3500 watts and 8 amp power; otherwise, it will take forever to power up your RV. 

Bear in mind that generators are heavy and noisy, so they can be annoying to tote around with you. They can also disturb wildlife and other RVers.

However, at the right time and in the right place, a generator is a useful and practical tool for life on the road. 

I hope you found this article helpful, and I wish you many happy adventures in your RV this year! 

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Rachel Horne - Writer for the camper lifestyle

Rachel Horne

Rachel is a freelance adventure writer and founder of Highly Sensitive Nomad. When she isn’t writing, she can be found wild camping in the mountains and swimming in the lakes of Europe.