Pick Your Deep Cycle Battery

Starting Lighting Ignition (SLI) batteries excel in high-start output where only light surface cycling takes place.

The deep-cycle battery is designed for applications that require deep, repetitive amperage drain, like boat/Marine Power, RV house power and in-start applications where the system load exceeds the alternator output for short duration's.

Types of Batteries

Batteries are divided in two ways, by application (what they are used for) and construction (how they are built).

  • The major applications are automotive, marine, and deep-cycle.
  • Deep-cycle includes solar electric (PV), backup power, traction, and RV and boat "house" batteries.
  • The major construction types are flooded (wet), gelled, and sealed AGM (Absorbed Glass Mat).
  • AGM batteries are also sometimes called "starved electrolyte" or "dry", because the fiberglass mat is only 95% saturated with Sulfuric acid and there is no excess liquid.

This video will review some of the best practices for battery selection. www.SolarPenny.com Visit us online at www.SolarPenny.com - Video is for basic product information only.

Note: This video is not intended to speak negatively / discourage the use of Interstate Batteries.

It is a best practice video for a successful system. As we suggest to out of state customers is the best battery you can get "locally" in your area is the Interstate 6 Volt Golf Cart Batteries which are easy to obtain at any Interstate Battery

Dealer in your area, or if you are a member of "Costco" stores they have a complete selection of Interstate Batteries at the best pricing.

I personally have Interstate Batteries in my car and truck but not in my Solar System, they are a great brand but their 12 volt line of "car, marine, rv and boat deep cycle batteries" will hinder your solar storage abilities.

Solar Penny is not liable for personal or property damage / injury caused by products in videos. Always seek the assistance of a licensed contractor for installation of electrical products.

Contact your local building department to ensure your system meets current city, county and / or state codes.

Flooded may be standard

  • With removable caps, or the so-called "maintenance free" (that means they are designed to die one week after the warranty runs out).
  • All AGM & gelled are sealed and are "valve regulated", which means that a tiny valve keeps a slight positive pressure.  
  • Nearly all sealed batteries are "valve regulated" (commonly referred to as "VRLA" - Valve Regulated Lead-Acid). Most valve regulated are under some pressure - 1 to 4 psi at sea level.
Expand your deep-cycle battery knowledge with this video tutorial which reviews the various deep-cycle battery technologies available on the market today, and what to consider when selecting a battery for a particular application.

Battery Lifespan

  • The lifespan of a deep cycle battery will vary considerably with how it is used, how it is maintained and charged, temperature, and other factors.
  • In extreme cases, it can vary to extremes - we have seen L-16's killed in less than a year by severe overcharging and water loss, and we have a large set of surplus telephone batteries that sees only occasional (10-15 times per year) heavy service that were just replace after 35+ years.
  • We have seen gelled cells destroyed in one day when overcharged with a large automotive charger.
  • We have seen golf cart batteries destroyed without ever being used in less than a year because they were left sitting in a hot garage or warehouse without being charged.
  • Even the so-called "dry charged" (where you add acid when you need them) have a shelf life of 18 months at most. (They are not totally dry - they are actually filled with acid, the plates formed and charged, then the acid is dumped out).

These are some typical (minimum - maximum) typical expectations for batteries if used in deep cycle service.

There are so many variables, such as depth of discharge, maintenance, temperature, how often and how deep cycled, etc. that it is almost impossible to give a fixed number.

  • Starting: 3-12 months
  • Marine: 1-6 years
  • Golf cart: 2-7 years
  • AGM deep cycle: 4-8 years
  • Gelled deep cycle: 2-5 years
  • Deep cycle (L-16 type etc): 4-8 years
  • Rolls-Surrette premium deep cycle: 7-15 years
  • Industrial deep cycle (Crown and Rolls 4KS series): 10-20+ years.
  • Telephone (float): 2-20 years. These are usually special purpose "float service", but often appear on the surplus market as "deep cycle". They can vary considerably, depending on age, usage, care, and type.
  • NiFe (alkaline): 5-35 years
  • NiCad: 1-20 years

Deep cycle batteries are designed to be discharged down as much as 80% time after time, and have much thicker plates.

  • The major difference between a true deep cycle battery and others is that the plates are SOLID Lead plates - not sponge.
  • This gives less surface area, thus less "instant" power like starting batteries need. Although these can be cycled down to 20% charge, the best lifespan vs cost method is to keep the average cycle at about 50% discharge.
  • Unfortunately, it is often impossible to tell what you are really buying in some of the discount stores or places that specialize in automotive batteries.
  • The golf car battery is quite popular for small systems and RV's. The problem is that "golf car" refers to a size of battery case (commonly called GC-2, or T-105), not the type or construction - so the quality and construction of a golf car battery can vary considerably - ranging from the cheap off brand with thin plates up
  • True deep cycle brands, such as Crown, Deka, Trojan, etc. In general, you get what you pay for.