What Is A Deep Cycle Battery? Your Complete Guide

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You’re probably wondering what is a deep cycle battery?

Deep cycle batteries are designed to be charged and recharged many times. Rather than offer a burst of energy for tasks like starting a vehicle, a deep cycle battery provides a steady stream of power over a long period of time. 

Deep cycle batteries aren’t for starting your car, truck, motorhome, or bat so you won’t be looking at ratings like cranking amps or cold-cranking amps since they’re meant to be used for longer periods of time. However, there are dual-purpose batteries, that serve the purpose of a deep cycle battery and a cranking battery in one. That’s for another post, though.

Deep cycle batteries come in four basic types, so let’s get into it!

Deep Cycle Battery Types

Lithium Ion

In a lithium battery, the electrons move back and forth from anode to cathode to create a charge in a solution of lithium salts. This battery can be almost completely discharged without consequence and its recharge rate is the fastest of any battery type. 

They are about half the weight of lead-acid batteries. All these points make them some of the best RV batteries for boondocking.

Our Pick
Battle Born Batteries
$874

Meet the 100 Ah 12 V LiFePO4 Deep Cycle battery, the pinnacle of deep cycle lithium-ion battery technology for your RV!

This battery weighs only 31 pounds but is capable of providing you up to 100 Amp of continuous current or 200 Amp of surge current for its whole life expectancy of 3000-5000 cycles.

It's made in the U.S.A. and comes with a 10-year warranty.

Flooded Lead-Acid Batteries

Flooded lead-acid batteries deep cycle batteries are built with lead plates that create “cells.” Distilled water fills each cell and is used as the transfer substance, which needs to be topped off monthly. 

Charging lead-acid batteries takes place over stages, leaving room for problems like overcharging or undercharging. They are usually the least expensive option for a house battery and can be recharged numerous times. However, lead-acid batteries sometimes have a shorter life than AGMs and lithium batteries.

Absorbed Glass Mat (AGM)

These deep cycle batteries have fiberglass between the plates in their cells for the electrolytes to pass through. It is considered a “dry” battery, and therefore, maintenance-free, as you won’t need to add distilled water. Their recharge rate is much faster than a lead-acid battery but not as fast or efficient as a lithium one.

Gel

Like AGMs, these batteries are maintenance-free. They transfer electrolytes through a gel substance created by sulfuric acid and silicate. 

Gel deep cycle batteries don’t emit gasses, so ventilation for the batteries isn’t necessary, but their charging rate is very slow. You will find these batteries used in electric wheelchairs and scooters.

Pros and Cons for Each Deep Cycle Battery Type

Lithium Pros

  • Usable capacity 80% to 100%
  • Extremely high charge rates
  • No battery memory
  • No maintenance necessary
  • Light weight
  • 2,000 to 5,000 charge cycles

Lithium Cons

  • Most expensive deep cycle battery option
  • Cannot be charged at low temperatures
  • Must have battery maintenance system (usually internal)
Victron inverters and Battle Born lithium deep cycle battery installed in the storage of a Grand Design Solitude RV
Our Battle Born Batteries and Victron Inverters

Lead-Acid Pros

  • Reliable
  • Tolerant of overcharging
  • Can deliver high current
  • Sold worldwide, easy to find
  • Indefinite shelf life

Lead-Acid Cons

  • Usable capacity 30% to 50%
  • Very heavy
  • Require monthly maintenance
  • Discharges gasses
  • Charge efficiency of 70% to 85%

Gel Pros

  • Does not spill
  • No maintenance
  • No off-gassing
  • Tolerant of heat
  • Charge efficiency of 85% to 90%

Gel Cons

  • More costly than lead-acid or AGM
  • Cannot tolerate fast charging
  • Can be ruined by overcharging
  • Has its own profile/setup

AGM Pros

  • Usable capacity 60% to 80%
  • Charges at much higher rates than lead-acid or gel
  • Does not spill
  • No off-gassing
  • No maintenance
  • Charge efficiency of 95%
  • Not affected by cold temperatures

AGM Cons

  • More costly than lead-acid
  • Can be ruined by overcharging

Deep Cycle Battery Maintenance

All deep cycle battery types, with the exception of lead-acid, do not require any maintenance. 

Distilled water must be topped off in lead-acid batteries monthly to keep the plates in each cell submerged. Failure to do so will render the plates useless and the battery will have to be replaced.

If you will not be using the batteries for long periods of time, a trickle charger can be attached to lead-acid and AGM batteries to keep them charged. You do not need to use it on lithium batteries, as they have their own internal battery management system.

Build up on a lead acid deep cycle battery

Installation

With deep cycle lead-acid, gel, and AGM batteries the installation is all the same. 

Just attach the positive terminal with the positive wire from your coach and the negative terminal with the negative or ground wire from your coach, or if you have two or more batteries, you’ll need to wire them in parallel or series, depending upon the battery size (12V or 6V).

Lithium batteries are attached in the same way (positive to positive, negative to negative or ground), but you will need a lithium-specific converter charger installed in your RV. 

Your rig may already have a convertor installed, but make sure it can be used with lithium batteries. Most standard convertors will not be able to charge the lithium battery to a complete 100% due to the voltage required but will be able to charge to around 80% full.

Pro Tip: Getting ready to install multiple deep cycle batteries? Read Wiring RV Batteries In A Series VS Parallel: What You Need To Know first.

How Long Will Deep Cycle Battery Last?

Good lithium batteries usually last 3,000 to 5,000 charging cycles. So depending on the frequency you recharge, they may last 3 to 20 years. 

Lead-acid batteries, if maintained correctly, can last up to 6 years, and AGM batteries will last 6 years, as well. Because they have their own charging profile, gel batteries can last 10 to 20 years.

Average Deep Cycle Battery Charging Time

  • Lithium charging time: 2 to 3 hours
  • Lead- charging time: 8 to 16 hours
  • Gel charging time: 5 to 10 hours
  • AGM charging time: 5 hours

Solar Charging Option

You can charge any type of deep cycle battery with solar panels. Solar systems usually involve a solar charge controller between the panel and the batteries to regulate the charge. 

Most installations also include a solar monitor, as well, so you can see how much energy is being created by the solar panels and how much is left in your batteries.

Pro Tip: Don’t want to do a full solar panel installation? Check out the 6 Best Portable Solar Panels to simplify the process.

Camper van in an open field with trees and mountains in the background, and with a solar panel plugged in to it.

Best Deep Cycle Battery Brands

When shopping for the right battery, customer reviews are always great to review. Here are the top deep cycle RV batteries on Amazon:

Bestseller No. 1
Renogy Deep Cycle AGM Battery 12 Volt 100Ah, 3% Self-Discharge Rate, 2000A Max Discharge Current, Safe Charge Most Home Appliances for RV, Camping, Cabin, Marine and Off-Grid System, Maintenance-Free
  • 【Warranty】2-year material and workmanship warranty guarantee.
  • 【Maintenance Free & Safe to Use】No acid leakage, no water refilling, and no harmful hydrogen gas. Manufactured with...
Bestseller No. 2
WEIZE 12V 100Ah LiFePO4 Lithium Battery, Up to 8000 Cycles, Built-in Smart BMS, Perfect for RV, Solar, Marine, Overland/Van, and Off Grid Applications
  • 10 YEAR WARRANTY: As the No.1 lead acid battery brand on Amazon, Weize newest Lithium Iron Phosphate Batteries are...
  • BUILT TO LAST: Our 12V 100Ah LiFePO4 Batteries live more than 2000 cycles at 100%/8000 cycles at 50%(Suggested) depth of...
Bestseller No. 3
WEIZE 12V 100Ah Deep Cycle SLA Battery, Rechargeable for Solar Wind RV Marine Camping UPS Wheelchair Trolling Motor
  • Dimensions: 12.99x 6.73x 8.43 inches (Replace UB121000, Renogy 100 AMP Hour). This sealed lead acid battery has a...
  • Deep Cycle Battery 12V 100 Amp Hour Sealed Lead Acid Rechargeable ; Parcel: 1 x Battery (screws included, but no wire...
Bestseller No. 4
Ampere Time 12V 100Ah LiFePO4 Lithium Battery, 4000+ Deep Cycle Lithium Iron Phosphate Battery, Built-in 100A BMS, Support in Series/Parallel, for RV, Camping, Marine, Trolling Motor, Solar (2 Packs)
  • 【Lithium Battery with LiFePO4 Cells】Ampere Time Lithium Iron Phosphate (LiFePO4) batteries are manufactured with...
  • 【Light weight & Long Lifetime】Ampere Time LiFePO4 battery is only 1/3 the weight of lead acid battery, weighing...
Bestseller No. 5
Interstate Batteries 12V 35Ah Deep Cycle Battery (DCM0035) Rechargeable Replacement Mobility Battery SLA AGM (Insert Terminal) Wheelchair, Trolling Motor, Scooter, RV
  • DEEP CYCLE MOBILITY BATTERY: Interstate Batteries DCM0035 professional-grade, high-quality battery developed...
  • DCM0035 BATTERY REPLACEMENTS: Compatibility Fit Guide located under Product Guides & Documents. ABEC WHEELCHAIRS, BEST...

Last update on 2022-12-08 / Affiliate links / Images from Amazon Product Advertising API

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4 comments
  1. Hi Rae, Jason

    Just FYI, you might want to change a minor thing on your latest article, you might be referring to your BattleBorns when you reference “Lithium Ion”, instead you should refer to those are “Lithium Iron Phosphate” which are different.

    PS. looking forward to more in-deep articles on your cat-18 modem

  2. I have two Costco 6v flooded golf cart batteries I bought for $89 ea 3.5 years ago. They still charge / run at 95 +% . I spent ~$100 for a 100W Renogy solar panel, wire & PWM controller. Since we live & camp most of the time in the Pacific N.W. I soon found out that unless you’re in direct sunlight, solar doesn’t work so well. I bought a Champion 2000W inverter generator for $450. We go out once a month 3-4 days with a 45 day ‘snowbird’ trip to the S.W. & a 30+ day Summer trip as well. About 60% – 70% boon-docking. My guess is that the average RV-r has hookups 90+% of the time. I sincerely doubt I’ve burned 3-4 gal’s of gas per year. I may need new batteries in about 2 years ? Assume I spend $120 per. 10 years I spent ~$400 vs $1k . I would have bought the other stuff regardless of the type of batteries. I see people spend $8k – $12k on “systems”. Unless your a full-timer and a large percentage off grid I have an issue with the arithmetic that claims it’s (LiPO) “cheaper”. .

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