RV batteries: What you need to know about them for trouble-free touring

Confused about batteries? Read this guide to learn everything you need to know about RV batteries for trouble-free touring.

RV batteries are defined by putting them into one of two categories. The first type is a starter battery that’s predominantly used to turn your vehicle’s engine over and supports the electrics associated with driving. The second type is the house battery, which is used to support an RV’s accessories and lifestyle features such as fridges, pumps, lighting and inverters. You could say it’s running all the household items. Let’s take a closer look at the types of batteries available.

Types of RV batteries

While many RV batteries on the market are lead/acid types, advancements in technology see the use of nickel-cadmium and lithium becoming more affordable solutions. Lead/acid batteries still retain a big share of the market and are manufactured in two main types: the cranking style and the deep cycle type.

Common types on the market are traditional flooded batteries, calcium maintenance-free, AGM (Absorbed Glass Mat), and gel. Think about the application before making any decision about which type is best to use as a starter or house battery for your RV. You also need to know how it will be used, the frequency of cycles, and its load-carrying requirements.

Maintenance-free house battery

Ever heard the term “maintenance-free battery” and wondered what it means? If you thought it meant you don’t have to open the caps and pour distilled water into the battery or forget about it once the battery is charged, you’re on the money. But while these statements are true, don’t expect to get a long life out of your RV house batteries if you take this approach! Here’s what you need to know about maintaining a battery to help it last longer.

Maintaining your RV house battery

The key to maintaining and extending the maximum life of an RV house battery comes down to having a good charging regime. All batteries discharge themselves over time, depending on the battery type. It could happen quickly or within weeks, while others may take months. So they’re not the type of thing you can simply set and forget. Another tip is to keep all the connections clean and free of dirt, grime and any corrosion as well.

Cranking vs house battery

There’s a difference between maintaining your cranking battery and your RV house battery. An in-vehicle car battery is designed to deliver a high current over short bursts and recharges rapidly via your vehicle’s electrics, i.e. the alternator. You can’t rely on the same charging circuit to recharge your house batteries. They will receive some current, but they won’t ever reach a state of full charge. Read on to learn how house batteries can be charged.

Types of chargers

There’s more than one way to keep your RV batteries charged, but not all deliver a perfect full charge. They all apply a current, which is termed as amperage (or amps for short), into the battery, and these are the types of chargers you can use.

• In-vehicle charging via an Anderson-type connector from your vehicle charging circuit.
• 240v mains battery chargers: there are multiple brands and types on the market, but all work differently. It’s important you purchase the right type for your needs.
• Solar panels coupled with a regulator: there are many different types and all work differently.
• DC to DC chargers: use the voltage from one battery to charge the other battery. They don’t create amperage but simply pass it through.
• Generators: some have a 12v output that allows you to connect directly to your batteries.

House battery charging systems for your RV

To get a fully charged battery for your RV, three basic stages of charge are applied, which achieve very specific voltage points. By understanding these stages and applying them correctly, it significantly increases the life of your battery. Many modern chargers have sophisticated electronics and offer a variety of other stages. But fundamentally, it comes down to these three: bulk, absorption, and float.

Bulk

This is the first stage in which the maximum amount of current (amps) is applied to increase its voltage.

Absorption

In this second stage, the voltage is brought to the maximum for that battery type. It can range from 14.4v for wet cell flooded batteries to 14.7v for AGM types. While voltage remains high, the amp rate is lowered. This has the effect of soaking all the cells in the battery and is critical to bringing it to a fully charged state.

Float

In the third stage, the battery is deemed to be full. The amps now applied to the battery are significantly reduced (at around one to two amps), while the voltage is held constant at around 13.6v. This is perfect in controlling the battery’s self-charge and keeps the battery at maximum charge and ready to go.

How flat is flat?

Determining when your RV battery is deemed flat isn’t easy, as manufacturers quote different voltages at different temperatures. Try claiming under warranty and you may find that manufacturers will shy away from claims if the voltage has been allowed to go too low. Many say a battery is flat when it’s below 12 volts, whereas the general industry rule is 10.5 volts. Be aware a battery’s life is shortened every time it’s discharged below the manufacturer’s minimum recommended voltage.

Monitoring your RV batteries

There’s many different gauges, displays and alarms available to help monitor batteries. Simple ones show the voltage at the time you look at it, and others have displays that show the number of hours left of use. There are even some that can provide graphs and logs indicating how the battery has been discharging. But if you want to keep things simple, just use a multimeter.

Protecting your batteries

As we can’t watch our battery’s voltage 24/7, a good way to prevent excessive discharge is through low-voltage cut outs. These simply get wired into the RV house battery circuit and can be set at a pre-determined voltage. They disconnect the battery from the appliance once the voltage drops below the set threshold.  

Answers to common RV battery questions

How do I store my RV’s batteries for long periods in between use?

The best scenario is if your RV is kept outside and has solar. Overnight, there’ll be some drain, and the following day the batteries will again fully charge from the sun. If your RV is undercover, leave the batteries on the charger. This, of course, assumes you have a smart charger and it goes to float. Another option is to use a timer and have the RV charger come on for 12 hours once a week. Lastly, a low amp trickle charger will also do the job.

Is there a risk that I can “overcook” the RV batteries by leaving them on charge?

A good quality charger that’s designed specifically to maintain batteries will charge only when required and hold the voltage high and the amps low. It’s important to have the correct charger for the system as it’s all about matching the charging circuit to the battery bank.

Are AGMs or Lithiums better as an RV house battery?

These days, Lithium batteries are the go for your RV. They’re better than AGM when comparing battery weight, depth of discharge, number of cycles, and speed of recharge. You’ll also need more AGM batteries than a single lithium model to deliver the same equivalent power. But your budget and purchase cost versus overall capacity use and proposed life span should also come into the equation. What’s best value for money for some might not be the case for others.

The bottom line of RV batteries

An RV electrical system that delivers the power you need and when you want it all starts with the right design. A lack of knowledge may see you purchasing any old battery for your RV that might work in the short term, but you could find yourself spending a lot more money in the long run. Getting to know how your system works can be the difference between trouble-free electrics or a new RV battery every year. We know what we’d rather!