RV Battery Basics

RV camping is partially powered by batteries that store electricity for use when not plugged into an electrical outlet. How do batteries work? What types of batteries are best for camping?

How should campers maintain RV batteries? Here are some RV Battery Basics.

RV Battery Logic

Your motorhome or towing vehicle already has a battery or two, used for starting the engine. SLI (starting, lighting, ignition) vehicle batteries are designed to produce a burst of electricity as the engine starts, then await the next start.

RV “house” batteries, those that power electrical appliances and lighting inside your camping quarters require a different kind of battery: deep-cycle.

A deep-cycle battery is specifically designed to hold a charge longer and deliver it slower than a vehicle starting battery. An SLI battery can’t be discharged very much before it is damaged. Deep-cycle batteries can be discharged (used) more.

The primary types of RV house batteries are lead-acid, AGM, and lithium-ion. Lead-acid batteries have been used in vehicles for nearly 100 years. They contain sulfuric acid that chemically reacts with lead to produce electricity.

Each cell in the battery is designed to produce 2.1 volts of direct current (DC). 12-volt batteries have six cells; 6-volt batteries have three cells. Fully charged, a 12V battery offers 12.6V of electrical power. Lead-acid batteries require periodic maintenance, adding distilled water as needed to keep the cells full.

Absorbed glass mat (AGM) batteries are “maintenance free” sealed batteries that can discharge to a lower voltage than lead-acid before being damaged. They are a newer design and are more expensive. More recently, lithium-ion (LI) batteries were designed for electronics and other more sensitive equipment.

They now are used as RV house batteries that can be fully discharged without damage to the battery. LI batteries are used to power many “electric cars.” Most expensive, LI batteries are popular in new RVs, especially units with solar power systems.

RV (and automotive) batteries are sized by groups. Make sure a replacement battery fits into the battery holder by selecting the same group as the previous battery.

The Battery Council International (BCI) groups for deep-cycle and marine batteries include 22NF, 24, 27, 30H, 31, 4D, and 8D, based on the battery case size. The sizing groups are different for 6V deep-cycle and 12V starting batteries.

The larger the battery the greater the amp-hours (amount of current amperes it can supply in an hour).

RV Battery Maintenance

All RV batteries require some level of maintenance, though for AGM and LI batteries it is simply making sure that terminals are clean and wires are tightly connected. Here are some maintenance tips to help you get more life from your RV battery.

• Wear rubber or neoprene gloves and eye protection when working around a lead-acid battery.
• If the battery fully discharges, make sure it has sufficient water in the cell (if lead-acid) and recharge it as soon as possible.
• Batteries unused for months should be disconnected from the RV and attached to a battery tender or trickle charger.
• Many RV manufacturers recommend that you disconnect a 12-volt battery from the unit during long periods of unuse because propane and carbon monoxide alarms as well as clocks can slowly drain battery power.
• Ask your battery retailer for a “state of charge” chart for your RV battery; it indicates the percentage of charge at specific voltages.
• Never let a lead-acid or AGM RV battery discharge below 10.5 volts. If possible, keep voltage above 12.24V (60% charge).
• Keep a voltage meter plugged in to a 12V plug in your RV to continually monitor battery voltage.
• At least once a year, clean battery cables and terminals with a battery terminal brush. Battery washers can reduce corrosion.
• On most RV rigs, the vehicle electrical system (motorhome, truck, car) will charge the house battery while driving.
• If you replace an RV battery, recycle the old one.

RV Battery Basics – What You Need to Know (Video)