7 Things You Need To Know About Your RV Battery

Last updated on May 13th, 2021 at 02:31 pm. Originally published on November 15th, 2019

best rv battery Your RV battery system is a critical component of your rig’s internal setup. It’s what powers everything electric inside your coach, from your overhead vent fan to your HVAC system to your refrigerator.

It’s important to understand that your RV coach battery is actually made up of two distinct systems: a 120-volt AC system and a 12-volt DC system. If you’re driving a motorhome, you also have a regular car battery which is used to start the engine, just as in your regular passenger vehicle.

The 120 volt system is the more powerful battery, which is used to run major appliances like your rooftop air conditioner or your refrigerator in the electric mode. In order to operate this battery, you either need to be hooked up to shore power (as you usually are at a developed campground) or running an electricity generator that can charge such a capacious battery. (It’s hard to generate that kind of power through solar, which is why running your AC unit on solar is nigh impossible!)

The 12-volt coach system charges when you’re hooked up, running your generator, or when you’re actually driving. This smaller battery system powers things like overhead fans, interior lights, and the water system, and can be used while the RV isn’t hooked up even without a generator — until the battery dies, of course.

Now that we have a basic understanding of what the RV battery system looks like, let’s dive into the nitty gritty on some of the most common questions surrounding this important system.

1. What is the best RV battery?

There are a variety of different RV battery choices on the market, and you’ll likely hear impassioned arguments for and against each type depending on which campers you ask. Here are some of the most common choices:

  • Deep-cycle batteries are a type of lead-acid battery, and is similar to the one you can find in boats and golf carts. It’s a lot like a car battery and uses the same chemistry to create and retain power, but a deep-cycle battery produces a steady amount of current over a longer period of time, whereas car batteries create a lot of current over a short period of time (since they then charge while you’re driving anyway). Deep cycle batteries come in a variety of subtypes, including flooded wet-cell batteries, absorbed glass mat (AGM) batteries, and gel-type batteries. Each of these have different quirks and maintenance needs.
  • Lithium batteries are an alternative to traditional lead-acid batteries, including the deep-cycle batteries offered with most modern RVs. Many campers who rig their RVs for solar power generation upgrade to lithium batteries, which, though expensive, offer a variety of benefits over other types: they’re lighter in weight, smaller, and don’t require the same kind of tedious maintenance other types of batteries do. (For example, wet cell batteries require you to check and replenish electrolyte levels, whereas lithium batteries are set-it-and-forget-it.) Lithium batteries also have a much longer lifespan than other battery types, and are typically rated for 5,000 cycles — as opposed to the 400 or so cycles most lead-acid batteries get. That said, they cost approximately three times more up front, which keep them out of the reach of some campers.

2. What is an RV Battery Bank?

No, there is no financial establishment for batteries; a battery bank is what you get when you join two or more batteries together. This increases voltage or amps when you need more power.

RV batteries in series
Joining RV batteries in series allows you to keep the same amperage but adds extra voltage. For example, joining two 6-volt RV batteries in series gives you a total of 12 volts, but the amps remain unchanged.

2 x 6 Volt batteries in Series

A jumper wire is used to connect RV batteries. The negative terminal of one battery is connected to the positive terminal of the other battery.
Another set of cables connects the remaining positive and negative terminal to whatever you are connecting the batteries to. Connected batteries should have the same voltage and amp rating.

RV batteries in parallel

A parallel RV battery bank increases the current but allows the voltage to stay the same. If you join two 6-volt RV batteries in parallel, you will get 6 volts, but the amps will now be increased. Parallel connections are done by connecting two positive terminals to two negative terminals. This creates a negative negative and a positive positive. The batteries can then be connected to your application and will drain equally when in use.

A series parallel bank is also possible. This allows you to increase voltage and amps. It requires a minimum of four batteries. Keep track of the connections you make. You can join as many batteries as you want to each other, though you may need an RV battery box to keep your separate cells safe and secure. Two sets of batteries connected in parallel can be joined together to form a series power bank.

RV battery in series and parallel

3. RV Battery Maintenance

Maintaining your RV batteries will depend, to some extent, on what type of batteries you have. As mentioned above, for instance, lithium batteries require pretty much zero upkeep.

But other types of batteries do have maintenance needs, as well as different lifespans. For example, the answer to the question,”How long do RV batteries last?” will be very different if you’re traveling with lithium ion batteries versus a wet-cell deep cycle battery.

For the most thoroughly RV battery maintenance instructions, check with the manufacturer of your specific batteries. That said, here are some basics.

  • Maintain electrolyte levels in flooded-cell batteries. Over time, flooded-cell batteries lose water with each charge cycle, and this water needs to be replenished. You must use distilled water to help reduce the chance of sulfation, or the formation of sulfate crystals that can occur when the battery plates are exposed to air. Check the batteries at least once per month, and ensure that they’re fully charged before performing the necessary maintenance.
  • Clean battery terminals to remove any corrosion that has built up. You can use a mixture of one cup of baking soda to a gallon of water or a commercial battery contact cleaning product, and utilize a toothbrush for scrubbing.
  • Allowing your batteries to get too low in charge can also increase sulfation. When your batteries fall below 80%, or 12.4 volts, sulfation can begin. Thus, always recharge your batteries in a timely manner after using them.
  • Try to recharge your batteries often. For example, if you discharge your battery to 50% every day, it’ll last twice as long as if you’d discharged it to 20% each day. However, also keep in mind that overcharging and hot temperatures also have negative effects on batteries over time.

4. RV Battery Storage

Recreational vehicles are usually stored away for months during the winter. Batteries naturally discharge over time, so your battery will go flat if you don’t look after it.

This will affect the life of your battery. Freezing kills flooded cell batteries. A charged battery cannot freeze.

AGM batteries resist damage from freezing better than flooded cell batteries, but it is important to prevent it from happening.

Consider removing your batteries from the vehicle and taking them home with you. Check the voltage every month and charge it if it falls below 80%. An overnight charge should be sufficient. If it is not possible to take the batteries out of your rig, you will need to take a few precautions to keep your batteries alive.

Firstly, disconnect your house batteries. Appliances such as radios, refrigerators, smoke detectors, and propane detectors consume tiny milliamps over time which can drain your battery. Just because everything is off doesn’t mean it doesn’t consume some form of wattage.

Charge the batteries as they naturally discharge. If you can gain access to your rig while in storage, ensure that you charge your battery fully once a month.

Unregulated solar panels may fail to maintain a charge — or, even worse, boil off electrolyte.

Converters should also not be left plugged in so as to charge the RV battery. This is a guaranteed way of boiling your RV batteries dry quick.

Check on your batteries periodically while in storage. Once a month is sufficient or you may need to buy new batteries next season.

4. RV Battery Monitors

Determining the true state of charge of an RV battery is difficult without a monitor. An RV battery monitor can tell you exactly where you stand, measuring the energy that’s flowing into and out of your battery as well as its state of charge or discharge.

rv battery monitors
Image via Amazon

There are many different kinds of RV battery monitors on the market, most of which can be installed aftermarket into your RV battery system. Most modern RV battery monitors include an LCD display that reads out all the critical data about your RV battery, as well as other newfangled upgrades.

For example, the Victron Battery Monitor includes a temperature sensor as well, and it’s Bluetooth compatible so you can track the state of your RV batteries by smartphone. But a battery monitor doesn’t have to be fancy or expensive to be accurate. You could also purchase the simple AiLi battery monitor for less than $45. It won’t send updates to your phone, but it does make checking your battery’s status as simple as a quick glance!

5. RV Battery Charging

When your RV is connected to an electric outlet, the batteries charge. An RV Converter/Charger that converts the power from the grid into 12-volt DC and then channels this to the adapter is fitted into every RV.

Batteries also charge when the motor of your motorhome (or tow vehicle) is running, or when you’re running your generator. You’ll know your batteries are charging if your rig is plugged in… as well as by checking your RV battery monitor!

While you can certainly keep your RV plugged in all the time, doing so can drain your wet-cell batteries’ water levels more quickly, so be sure you’re checking them often if you camp this way. And remember, letting your batteries get too low in charge is bad for their overall lifespan, so try to keep them charged on a regular basis.

6. How much does an RV battery cost?

As mentioned above, the cost of your batteries varies wildly with which kind of battery you get. For instance, a single, 12-volt, regular wet-cell lead acid battery might cost several hundred dollars, while lithium battery setups can cost thousands. That said, lithium batteries’ extended lifespans can mean their cost-effectiveness is actually much better in the long run, so if you can foot the expense upfront, it’s worth it.

7. How do you install an RV battery?

To install an RV battery, start by turning off all of the objects that draw power from the battery, including minor appliances like overhead lights. Make a note of where the current battery is located, and then disconnect the cables — negative first, then positive. Clean the cables and the new battery’s terminals if necessary, and then insert the battery and reattach the cables. Install any hold-down hardware that accompanies the battery, and then give it a test run!

Frequently Asked Questions about RV Batteries!

To finish out this post, here are some of the most commonly-asked questions about RV battery systems with answers.

How long do RV batteries last?

The lifetime of your RV battery depends on how well you maintain it, how often you utilize it, and what kind of battery you have. Lithium ion batteries may last for as many as 5,000 charge cycles, whereas deep-cycle batteries may only last for 400 or 500.

How many batteries does an RV or motorhome have?

As mentioned above, your RV coach has two separate battery systems, a 12-volt DC system and a 120-volt AC system. There’s also an automotive 12-volt system for starting the engine and running basic automotive functions, just as there is in your car.

Does driving charge the RV Battery?

Yes, it does!

Does my RV need a battery?

Well, it doesn’t need one… but everything will certainly work a lot more easily if you’ve got batteries on board!

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