RV Battery Basics by Dometic

RVs use deep cycle, valve–regulated lead–acid (VRLA) batteries that can be regularly discharged and recharged. There are two common types of VRLA batteries – gel and absorbed glass mat (AGM) – with the latter being more popular. A third battery type – lithium–ion – is quickly gaining
popularity in the RV community based on its efficiency, performance, and longevity.

Gel batteries are based on older technology. While they are sealed and do not spill, they charge more slowly than other battery types and require a compatible charge controller.

AGM batteries, like gel batteries, are sealed and don’t spill. They also do not vent gas and require no maintenance. AGM batteries charge quickly and are more resistant to low temperatures than gel alternatives. However, they require the use of a charge controller to prevent overcharging. 

Lithium–ion batteries are an attractive new option for RV operators.They provide high–performance,efficient charging in al ow–weight package. They are safe, require no maintenance, and offer a long lifecycle. While lithium batteries are expensive, the cost has dropped considerably, making them a compelling alternative to more traditional battery options. 

RV lithium–ion batteries offer several advantages, including:

  • An extended lifespan of up to ten years versus three years for traditional lead–acid batteries
  • Weight savings of up to 65 percent
  • Zero maintenance
  • Safer to store. Lithium-ion batteries don’t vent potentially
    dangerous gases and can be stored in enclosed locations
  • Greater discharge depth. Lithium-ion batteries can be
    discharged greater than 80 percent without ill effects
  • Faster charging and better discharge efficiency. Lithium-ion batteries can be charged and discharged much faster than lead-acid batteries.

Battery Buying Tips

How many batteries will I need? Your battery requirements are based on the energy consumption of your RV. The more appliances you plan to run, the higher your consumption. RV batteries can also be wired together to form a ‘battery bank,’ providing either higher voltage (wired in series) or greater capacity (connected in parallel).

What type of batteries should I purchase? For most off–grid applications, high–quality AGM batteries strike an excellent balance between performance and price. As lithium–ion prices drop, they may offer a better alternative for demanding RV applications.

Heavier is usually better. With traditional AGM batteries, more lead equals more battery capacity.

Ask for the warranty. Be sure to check out the manufacturer’s battery warranty and ask about their service and support capabilities.

Should I choose 6v or 12v batteries? While 6v batteries offer more amp hours,12v batteries, in some configurations, can provide more redundancy.

RV applications require a 12v current, so you’ll need two 6v batteries connected in series to generate those12volts. If one of those 6v batteries goes bad, you’ll have no usable power.

However,iftwo12vbatteriesareconnected,and one does not work, you’ll still have usable12v power.Typically, multiple 6v batteries are used if you’re looking for maximum power or a re planning to have a large battery bank.