Within our first year living on the road, we quickly learned more about RV batteries than we ever wanted, mostly by making costly mistakes. Almost 10 years in, we have mastered the RV battery system and going to share everything you need to know as a beginner. You may wonder what the fuss is about with RV batteries. Why do you have to maintain them, and how can you make sure yours lasts as long as possible?
This guide will give you a basic understanding of RV batteries, what to look for when buying one, and how to take care of it for optimal performance. So let’s get cranking!
- RV Battery Types
- RV Battery Chemistry
- What Is the Voltage of RV Batteries
- How to Check Power Level of Batteries?
- How Long Do RV Batteries Typically Last?
- What Is the Longest-Lasting RV Battery?
- How Many Batteries Do I Need in My RV?
- How Do RV Batteries Charge?
- How Do I Keep My RV Battery Charged When Not in Use?
- What Do You Do With RV Batteries in the Winter?
What Are RV Batteries?
RV batteries are what store energy to provide power to the appliances and other electrical devices within your motorhome, trailer, or camper. Your lights, fans, control panels, LP gas detector—just about anything electronic—run off your RV batteries when you are not plugged into shore power. Even when plugged in the RV batteries are being charged and still part of the power system.
Pro Tip: Batteries are just one component of your RV electrical system. Make sure you understand these Helpful RV Electrical Basics for Beginners.
RV Battery Types
It’s important to understand the difference between starting and RV house batteries. If your RV is motorized, it will have a separate set of batteries for the engine than the RV portion. Trailers do not have starting batteries as they are in the tow vehicle and totally separate.
The starting battery in a motorhome is the energy storage device that provides power for the engine to start and run the chassis components. Most RV starting batteries, like in passenger cars or other vehicles, are lead-acid-based 12-volt batteries.
This type of battery has been around for decades because of its specific ability to provide a large amount of starting (or cranking) power. Starting or chassis batteries are not designed to provide long-duration power. They are instead for large short bursts (starting) and then immediate recharging. Drawing them down will damage them.
House (Deep Cycle)
As mentioned, an RV house battery (sometimes multiple batteries called a battery bank) provides power to the different electronic equipment associated with the living quarters of your motorhome, trailer, or camper.
The house battery powers the lights inside the RV, the refrigerator, power outlets, fans, and other interior items. A house battery might also power some exterior appliances. That includes an RV porch light, awning lights, the awning itself (if it has an electric motor), and other outdoor devices connected to the RV’s power source.
Despite the type of chemical make-up, an RV house battery should be of the deep-cycle variety. A deep-cycle battery provides sustained power over a long period. It’s better than a starting battery at being able to withstand being consistently depleted and charged.
RV Battery Chemistry
Battery chemistry technology has a tremendous effect on the efficiency of a deep-cycle battery, how long it lasts, how well it performs, and how safe it is. Let’s take a look at the different battery chemistries used in RVs.
A flooded lead-acid deep-cycle battery is similar to the starter battery you’re likely familiar with in cars and other vehicles. The difference is that the deep-cycle version provides sustained power instead of the large amount of cold-cranking amps necessary to start a vehicle’s engine. Deep cycle flooded lead acid batteries are built with thicker internal materials that last longer as they degrade.
Flooded is the cheapest type of deep cycle battery available and the most common type most RV’s are supplied with. Even though it’s the most used it’s no longer considered a highly efficient option. Flooded lead-acid batteries can only be depleted to about half capacity before the battery suffers irreparable damage that shortens its lifespan and reduces its effectiveness.
Flooded lead-acid batteries also require routine maintenance, which requires exposure to the gasses and acids within the battery. This can be dangerous if you’re not careful. These batteries also poorly handle the vibrations and jostling of RV travel and can put off hazardous gasses when damaged. Because of these dangers, lead acid batteries can never be installed in the same airspace as living quarters. They always need a separately ventilated compartment making installation more challenging.
Flooded lead acid batteries need to have their water levels checked occasionally and topped off with distilled water.
AGM (Still Lead-Acid)
A deep-cycle absorbed glass mat (AGM) battery bases its function on flooded lead-acid chemistry, but its build improves on the standard technology. AGM batteries still suffer the same depletion issues. But, being completely sealed, they are spillproof, don’t require routine maintenance, and are much more resistant to constant vibration.
GEL (Still Lead-Acid)
Gel deep-cycle, sealed batteries are very similar to AGM. They have a different technology that turns the fluid inside into a gel. It performs much the same as AGM but can handle deeper discharges a little better. But, AGM batteries handle cold temperatures better than gel batteries.
A gel battery is generally more expensive than an AGM battery.
Lithium deep-cycle batteries have quickly become the best overall option for RV house batteries, particularly those made from the LiFePO4 (or lithium iron phosphate) technology. Being innately non-combustible, they are extremely safe and handle RV travel quite well.
Like sealed lead-acid batteries, lithium batteries require no maintenance. Unlike lead-acid batteries, they are much lighter and take up less space, which is a huge benefit to an RV. They can also be discharged to near-zero without suffering the damage that lead-acid batteries do. That equates to more effective power when comparing amps to amps.
Lithium batteries also last many times longer than lead-acid batteries and can be quickly recharged. That gives them some tremendous advantages over their lead-acid counterparts. We have written extensively on lithium batteries and featured them in many of our videos as well. Personally, we feel they are a far superior option in all aspects, including safety.
What Is the Voltage of RV Batteries
The voltage of most RV batteries is 12 volts. That’s because most RVs and the various appliances are 12-volt compatible. There are, however, a few other voltage options on the market. 12V is also considered low voltage and is touch-safe. You cannot get shocked by 12V.
Sticking with the required 12-volt standard, some people opt to wire two 6-volt lead acid batteries in series, providing 12 volts of power. The benefits are that 6-volt lead-acid batteries can handle being charged and discharged more frequently than 12-volt lead-acid batteries. They have a longer lifespan and often have larger amp-hour capacities. Two 6 volts, however still do not compare to one 12V lithium battery.
Some large RVs with many appliances and greater electricity needs may utilize 24- or 48-volt batteries. This is uncommon, though, because of the higher cost and less availability of compatible appliances and components. Frequently when opting for higher voltage it’s so that higher current solar systems can be added. We run 24V on our ultimate fifth wheel RV solar system build for this purpose but convert it back to 12V for all primary appliances in the RV.
How to Check Power Level of Batteries?
Most newer RVs come with a voltage meter installed, making it easy to check the power level of your batteries. They have a readout so that you can monitor what voltage your battery is at, alerting you whether or not you need to charge them.
A resting lead acid battery fully charges when it’s between 12.6 volts and 12.9 volts. When the resting voltage is at 12.0 volts to 12.1 volts, the battery is at about 50% capacity. If it’s a lead-acid-based battery, recharge it when it reaches 12.0 volts to 12.1 volts or sooner. If the battery’s resting voltage is at 11.0 volts or lower, it is completely dead and needs charging. The lifespan and capacity of a lead-acid battery reduce at this point.
If you have lithium-ion batteries, 12.8 is low, and 13.6 would be a charged battery. The slightly higher voltage also helps the batteries operate more efficiently and provide more energy.
If your RV didn’t come with a voltmeter installed, you can use a multimeter to read the voltage of the batteries. However, this is rather cumbersome. A multimeter is a handheld device that requires physical access to the batteries to use it and get a reading of the voltage.
A better option for monitoring battery capacity is installing a battery monitor with a shunt and current sensor. Though it’s not difficult to install, a battery monitor with a shunt allows you to measure the real-time voltage of your battery. You can also use some battery monitors to calculate the current percentage of charge, your power consumption, remaining runtime, and more.
How Long Do RV Batteries Typically Last?
If you do your best to maintain a lead-acid battery to its optimum performance, it will likely last between two and five years. A traditional lead-acid battery will generally fall on the lower side of this estimate, while AGM or Gel batteries may be at the high end.
A high-quality lithium battery can last much, much longer. Even with constant use, a LiFePO4 battery could last more than 10 years. If used less frequently but stored appropriately, a lithium battery could last upwards of 20 years. We have used our lithium batteries with very high drains daily for over 5 years and have seen minimal degradation.
What Is the Longest-Lasting RV Battery?
The longest-lasting RV battery on the market is the LiFePO4 battery which utilizes a cylindrical cell technology. A few companies manufacture LiFePO4 batteries, but Battle Born is one of the best-known and most respected manufacturers.
Battle Born is well-regarded for its rugged, durable batteries that withstand harsh conditions. They are also renowned for excellent customer service and a hassle-free warranty.
➔ You’ll never see us using any other lithium battery brand. Find out why: The Real Reason We Installed Battle Born Lithium Batteries (Again) [2022 Review]
How Many Batteries Do I Need in My RV?
How many batteries you need in your RV is a bit of a tricky question to answer. Though the size of your rig is a factor, the number is based more specifically on your power needs and the capacity of the individual batteries.
In general, however, a small Class B, Class C, campervan, or smaller travel trailer may only require a single battery. This is especially true when opting for a high-quality lithium battery, which can easily handle most of the needs of a smaller rig. Most smaller RVs are limited by space, thus limiting the amount of energy-siphoning appliances.
As you scale up to a large Class A or Super C, there’s much more room for power-hungry appliances. That includes a washer and dryer, dishwasher, multiple air conditioning units, a residential refrigerator, an electric range, and other items. Many of these larger rigs will have as many as eight 12-volt house batteries wired together into a bank of batteries.
If you are considering adding batteries we recommend you conduct an energy audit to determine your energy needs. We wrote an extensive article about how to do this when figuring our how much solar you need for your RV. Determining RV battery needs is one part in figuring out solar requirements.
How Do RV Batteries Charge?
No matter the size of your battery or battery bank, you’ll eventually have to charge an RV’s house battery. There are several ways to do this.
Most RVs can charge the house battery via a converter when plugged into shore power. That can be at an RV park, campground with electrical hook-ups, or when plugged in at a residence. Many also have an onboard or portable generator, which essentially takes the place of shore power when it’s unavailable. The converter is basically a battery charger that charges the batteries from 120V AC power. Once the batteries are charged, it continues to provide the 12V power needed for the RV.
Drivable motorhomes allow the house battery to charge when the engine is running. This allows the house battery to charge while traveling down the road. If you don’t have a generator, starting the motorhome can thus charge the battery. Some travel trailers and fifth-wheel trailers can do this if wired and connected appropriately to the tow vehicles battery system.
Another increasingly popular option for keeping RV batteries charged is using solar panels. This is an especially economical way to charge your batteries once you can account for the solar power equipment cost. It’s also a great way to charge RV batteries when off-grid or in places where you’d rather not run a noisy generator.
How Do I Keep My RV Battery Charged When Not in Use?
If you’re not going to use your RV for a short period, it’s best to fully charge the house battery when you park it. Most RVs also have a power kill switch, which helps keep smaller systems (such as control panels) from drawing on the battery. You should engage the kill switch and monitor the battery’s voltage while parked. Top off the charge if it dips to about 12.4 volts to 12.5 volts.
If you don’t want to have to remember to constantly monitor the voltage, you can hook the battery up to a charger with a trickle charge setting. A good trickle charger can detect when the battery has lost some of its charge and replenish it. However, it should also know when the battery is full to not overcharge it.
What Do You Do With RV Batteries in the Winter?
If you’re not going to use your RV battery for a prolonged time, it should be stored and kept charged. The best thing to do is remove it from the RV. Store it in an area above freezing temperatures (over 32 degrees Fahrenheit).
However, as long as it’s kept charged most batteries can be stored below-freezing temperatures just fine. If you expect extreme cold (below -15F) for long periods of time it’s best to remove a battery and keep it warmer. Batteries all use chemical reactions and the cold can cause damage.
While disconnected and in storage, the battery can still lose its charge, which you don’t want to happen. That can damage the battery. The best thing to do when the battery is in storage is to attach it to a charger that can perform a trickle charge to keep it topped off.
Take Care of RV Batteries and They Will Take Care of You
Now that you know more about RV batteries, it’s time to get out there and hit the open road!
But before you do, take care of your batteries so they can take care of you. Select the best battery possible for your RV and maintain it as best you can. With just a little bit of TLC, your RV batteries will last for years and keep you powered up for all your adventures.
When you’re ready to tackle your first RV solar project, start here: The Beginner’s Complete Guide to RV Solar Battery Chargers
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