How To Make The Best Choice On 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. 

These batteries are especially useful in RV coaches, golf carts, and for marine applications, and they come in four basic types.

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 deep cycle battery can be almost completely discharged without consequence and their 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.

Flooded Lead Acid

These 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 of 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, but sometimes have a shorter life than AGMs and lithium batteries.

Gel

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

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.

More From Getaway Couple

Pros and Cons for Each 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
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

Lithium Cons

Lead Acid Pros

  • Least expensive
  • Reliable
  • Tolerant of overcharging
  • Can deliver high current
  • Sold worldwide, so 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

Maintenance

All deep cycle battery types, with the exception of lead-acid, do not require any maintenance. However, 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 (12 volt or 6 volt).

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.

How Long Will Deep Cycle Battery Last?

Good deep cycle 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.

Charging Time

  • Lithium charging time:  2 to 3 hours
  • Lead acid 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.

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

Brands

Here are the top deep cycle RV batteries on Amazon:

Bestseller No. 1
Weize 12V 100AH Deep Cycle AGM SLA VRLA Battery for Solar System RV Camping Trolling Motor, in Series 24V 36V 48V
  • LFP12100 Deep Cycle Battery 12V 100 Amp Hour Sealed Lead Acid Rechargeable ; Parcel: 1 x Battery (screws included, but...
  • Dimensions: 12.09 x 6.65 x 9.17 inches (Replace UB121000, Renogy 100 AMP Hour). High Performance, Deep Cycle: Long...
Bestseller No. 2
Renogy Deep Cycle AGM Battery 12 Volt 100Ah for RV, Solar Marine and Off-grid Applications, Gray
  • Maintenance Free: Manufactured with thick absorbent glass mat (AGM) separators and advanced valve regulated technology,...
  • Excellent Discharge Performance: Proprietary quinary alloy plates and specially treated plate grids enable low internal...
Bestseller No. 3
Universal Power Group 12V 100Ah Solar Wind AGM SLA DEEP Cycle VRLA Battery 12V 24V 48V
  • UPG #45978 UB121000 12V 100Ah
  • Dimensions: 12.17 inches x 6.61 inches x 9.16 inches. Weight: 63.93 Lbs
Bestseller No. 4
Optima OPT8016-103 Batteries D34M BlueTop Starting and Deep Cycle Marine Battery
  • 12-Volt, 750 Cold Cranking Amps, Size: 10 inches x 6 7/8 inches x 7 13/16 inches tall, Weight: 43.5 pounds, Dual SAE &...
  • Optimal starting power even in bad weather
Bestseller No. 5
Battle Born LiFePO4 Deep Cycle Battery - 100Ah 12v with Built-in BMS - 3000-5000 Deep Cycle Rechargeable Battery - Perfect for RV/Camper, Marine, Overland/Van, and Off Grid Applications
  • BUILT-IN BMS: BMS stands for "Battery Management System" - the brain of our deep cycle lithium batteries. Our BMS...
  • LITHIUM ION TECHNOLOGY: Unlike Lead Acid batteries, Battle Born's deep cycle lithium ion batteries have unlimited...

Check out Battle Born Batteries

We have been using Battle Born Batteries for almost two years and absolutely love them. We started with just replacing our single battery with a Battle Born then quickly upgraded to a set of 6. It has allowed us to boondock over 200+ nights and easily pay off our upfront investment.

Single 100ah 12v Battery

A single battery is a great place to start. Don’t every worry about maintenance again after you install this! You won’t have to worry about replacing it for at least 10 years.

Getaway Couple Battery Bundle

This bundle is everything we got to make our RV an off-grid warrior. We power every outlet in our RV with no worries! This setup has been tested for over 200 days off-grid and has exceeded expectations.

Last update on 2021-02-20 / Affiliate links / Images from Amazon Product Advertising API

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3 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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