Last Updated: February 5, 2023

How To Charge An RV Battery

Just getting into van life and you’ve got some questions about RV batteries? You’ve come to the right guide because these van lifers will tell you all you need to know about charging RV batteries!

Why they’re different from car batteries, what types of RV batteries exist, and the many different ways you can charge them are all covered in this detailed guide on RV battery charging. Whether you’ve got an old lead acid battery, a brand new lithium one, or something in between, you’ll find all the information you need in this guide on how to charge an RV battery!

Ways to Charge An RV Battery

1. Charge from the Alternator

Using the alternator to charge RV batteries is a popular option and it’s something you can do without having to invest in a battery charger or a solar power hookup. If you own a motorhome, your vehicle’s alternator is already charging both batteries while you are driving.

If you’re wondering if you can use an alternator to charge the RV battery when it’s parked, you can. You need a truck or any tow vehicle really, and a 7-pin travel trailer plug. Just connect your RV deep cycle battery to the alternator of the other vehicle and let it charge.

It’s worth noting that this takes quite a long time and it’s not really a good long-term solution. On the other hand, it is possible to speed up this process significantly – all you need is a DC to DC RV battery charger. It’s kind of like a fast charger for the RV – it boosts the charging amps by about four times, allowing for a much quicker charge from the alternator.

2. Charge from Solar Power

Solar Panel

Solar power has become increasingly popular over the past couple of decades, and more and more van lifers are putting solar panels on their campers to be able to charge their RV batteries. It’s a great option because it’s entirely sustainable and environmentally friendly, plus it helps keep the weight of your RV to a minimum.

Setting up a solar power system is a great solution for campers who are usually on the road in the warmer months. Relying on a solar panel in the winter is not really a great option, since it will usually require at least 6-7 hours of direct sunlight to be able to fully charge an RV battery.

If you’re considering turning to solar power to charge your RV, you’ll need to figure out how many panels you need on the vehicle. You need to figure out how much power you’re consuming and choose a solar panel (or more) with the appropriate wattage. Also, you’ll need to invest in a few other gadgets like a charge controller, which prevents your car battery from overcharging.

3. Charge from Shore Power

Using shore power to charge your RV batteries is easy and automatic. All you need to do is plug in your RV’s shore power cord into a 120v AC power outlet and the RV battery will automatically start to charge. Your RV converter helps with this process because it converts the AC power into DC power so that the battery can charge properly.

It’s worth noting that this is the most common way of charging RV batteries. You can do this absolutely anywhere as long as there’s a 120v AC power outlet, but it’s most common for people to charge their RVs at campsites that have electrical hookups.

4. Charge from a Generator


When there’s no shore power available, a generator is a decent alternative. You charge the RV batteries via a generator the same way you charge them with shore power – just plug the RV power cord into the generator and you’re set. One thing to note is that you should never do this while the generator is inside the RV – it should always be outdoors, on firm ground, and you’re supposed to let it warm up a bit first.

One thing to keep in mind is that the generator needs 120v/30 amp receptacle for the RV battery chargers. If it’s only got a 220v receptacle, you will need an adapter in order to charge your RV house battery.

What Happens When You Undercharge Your RV battery

Undercharging a lead acid RV battery is one of the best and quickest ways to destroy it entirely. I’m not even kidding – it can lead to permanent damage because lead sulfate will form on the battery plates. It’s not a big deal if it happens once or twice, but if you’re regularly undercharging your lead acid RV battery, you’re just reducing its capacity and shortening its life.

Also, it’s important to note that lead sulfate will accumulate over time. Every time you undercharge the battery you allow more lead sulfate to accumulate on the battery plates, and if you don’t fully charge the battery soon, it will harden into crystals. This can quickly reduce your total battery capacity by as much as 50%, and eventually, it can just kill the battery entirely.

It’s important to note that undercharging your battery if you’re in a pinch is fine, as long as you’re certain that you can fully charge it very soon. Undercharging your RV battery every time, and then waiting for too long to fully charge it again is what you’re supposed to be doing if your only goal is to kill your RV battery.

What Happens When You Overcharge Your RV battery

Overcharging your RV battery is just as harmful as undercharging it. RV batteries use water when they’re charging, and if you’re always overcharging them, you can easily corrode the batteries. They’ll use more water than necessary which will result in a severe loss of water, the plates can easily corrode, and the battery can die entirely.

This applies mainly to lead acid RV batteries, but it’s worth noting that gel cell and AGM batteries are both sensitive to overcharging as well. With a lead acid battery, you can just add distilled water if you overcharge the battery – you can’t do this with the two other types because they boast a different, sealed design.

Lithium batteries are less sensitive to overcharging, meaning that it’s much harder to destroy them by overcharging, but doing it often can significantly reduce the total battery capacity and battery life.

Safety Tips When Charging Your RV Battery

We’ve covered all the most important things you need to know about charging RV batteries, and now we’ve got a few tips for you that will help ensure both you and the battery stay safe while it’s charging!

Be Extra Safe With Lead Acid Batteries

Lead acid batteries are spillable, which means that if you handle them improperly, you could get the toxic chemicals everywhere in the RV. That’s why they need to be mounted in a ventilated area and why you need to wear gloves whenever you’re about to touch the battery.

Also, it’s important to check for sulfate buildup from time to time and scrape it off the plates before charging. This helps prevent further buildup, and it helps your RV battery live a longer life.

Get A Charge Controller (For Solar Charging)

If you’re going the environmentally friendly way, don’t forget to install a charge controller in your RV. Without it, the solar panels can easily overcharge your RV batteries and do more harm than good. So, if you want solar power in your RV and you don’t want to deal with dead RV batteries, a charge controller is essential in your motorhome.

Never Charge In Extreme Weather

Extreme heat and cold are both harmful to RV batteries, and you should never charge them in extreme conditions. Charging batteries at below-freezing temperatures will cause crystallization, which will damage the battery and make it more susceptible to failure due to hard use.

Lithium batteries also shouldn’t be charged in extreme cold, but it’s worth noting that many of them have a battery management system that ensures they can only accept a charge in suitable conditions. Also, RV batteries should never be charged at temperatures exceeding 122°F (50°C).

About the Author Roger Timbrook

Roger is a little obsessed with travel. He has been to over 40 countries, broken 3 suitcases and owned over 10 backpacks in 12 months. What he doesn't know about travel, ain't worth knowing!

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