Choosing the Best Batteries

2009 Battery Specifications Guide
Beginner

Inside this Article

Most battery manufacturers have a full line of products.
Most battery manufacturers have a full line of products in different amp-hour capacities and voltages.
A classic Trojan L-16H flooded lead-acid battery
A classic Trojan L-16H flooded lead-acid battery—420 AH at 6 V.
Golf cart batteries
Golf cart batteries are inexpensive but shorter-lived than industrial batteries. They can be good “starter” batteries for people new to battery use and maintenance.
Surrette industrial battery
Some large, industrial batteries, like this Surrette model, come in single 2 V cells.
A Hup industrial battery from Northwest Energy Storage
This Hup industrial battery from Northwest Energy Storage demonstrates how single cells are contained in protective steel cases.
Bogart Engineering Tri‑Metric AH meter
An AH meter like the Bogart Engineering Tri‑Metric is an important tool for monitoring battery state-of-charge.
A single 2 V FLA cell, in a protective steel case.
A single 2 V FLA cell, in a protective steel case.
A Sealed FullRiver AGM Battery
A sealed FullRiver, similar in dimensions and capacity to a flooded L-16.
Concorde’s Sun‑Xtender AGM battery
Concorde’s popular Sun‑Xtender battery is about the same size as an automotive starting battery.
Sealed batteries installed on their sides
Sealed batteries can be installed on their sides to limit the amount of space required.
Most battery manufacturers have a full line of products.
A classic Trojan L-16H flooded lead-acid battery
Golf cart batteries
Surrette industrial battery
A Hup industrial battery from Northwest Energy Storage
Bogart Engineering Tri‑Metric AH meter
A single 2 V FLA cell, in a protective steel case.
A Sealed FullRiver AGM Battery
Concorde’s Sun‑Xtender AGM battery
Sealed batteries installed on their sides

Whether you need batteries to store energy for your off-grid home, or you want backup power to keep the lights on when the grid goes down, understanding the different battery specifications will help you select the ideal batteries for your application.

To choose the right battery, you first need to know what you are trying to accomplish. What system type are you working with—off-grid or grid-tied? Where will the battery bank be located? How much maintenance are you prepared to do? And how often (or not) do you want to replace your batteries? The answers to these questions will dictate which batteries make the most sense for your renewable energy system.

Budget also plays a big role in which batteries you choose. Buying batteries is a long-term investment, and skimping on these important components can cripple a system. Getting it right the first time will pay off in performance and longevity. However, simply buying the most expensive battery does not ensure you are meeting the needs of your renewable energy system. For your system to operate and perform well, it is crucial to understand the various battery specifications and how they relate to RE system design.

Batteries used in an RE system can be broken down into two basic categories: heavy duty/commercial and industrial. A common heavy duty/commercial-type battery bank may be comprised of several 6 V, 390 AH (L-16 type) batteries. An industrial battery pack will usually be large 2 V cells (with thicker lead plates) pre-wired to 12, 24, or 48 V and encased in a large metal housing. You will pay more for the industrial battery bank than you will for the equivalent battery pack made of heavy duty/commercial batteries, but you gain longer battery life and a better warranty. 

If you are working with an installing dealer, they often have preferences about which batteries they will use. For example, some installers will only work with L-16 type batteries because they are the largest that they can readily move by themselves—each L-16 battery weighs around 120 pounds, whereas industrial batteries can weigh thousands of pounds, making them difficult to maneuver without disassembly. If you have no experience with batteries, shorter-lived, less-expensive batteries may be a better choice to get you up to speed with battery operation. But some installers will still lean toward the expensive industrial battery packs because they want to minimize battery replacement. This can be especially beneficial in an off-grid setting where just getting to the site may be difficult—much less moving the old batteries out, getting the new ones in, and having to haul the old ones away for recycling. However, industrial batteries are only a wise investment if you are confident in your ability to maintain the battery bank.

Using This Guide

This guide lists specifications for different lead-acid batteries, the most common chemistry used in RE systems. Exotic technologies such as lithium ion, liquid pocket plate nickel cadmium, nickel iron, and nickel metal hydride batteries are not included here because they are either unavailable or too costly for consideration. Get familiar with battery terms and definitions; they’ll give you an understanding of each spec’s relevance to designing an optimal battery system.

Choosing Your Batteries

As with any RE system investment, your best bet will be to identify your true needs and design a system around them. Grid-tied battery backup systems generally use low-capacity  banks made up of sealed, non-industrial batteries that will meet your needs for running critical loads like refrigeration and lighting during power outages. They are generally designed to stay at float most of the time with only occasional cycling, and are often made with calcium alloyed with the lead which helps lower battery self-discharge losses.

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Comments (3)

Thrush's picture

Have you heard that lead acid batteries must be kept within 20% of full charge for longevity? Have you heard that Nickel Iron batteries are not significantly damaged by freezing, full discharge, and are tolerant of over charge? Redundancy on a remote homestead is desirable. Natural progression of a system is inevitable and in our case with better batteries, more water pumping, refrigeration, additional solar panels, more summer cooling, misting, etc I discovered this advantage which is not listed in any literature I've seen. It is natural with increased consumption that a 24 V system would parallel a 12V system, and maybe in the future even move to a 48V system. But the important part is that voltage bracketing of lead acids with alkaline cells (they have a wider voltage range) works really well. As a ham radio operator, maintaining the 13.5 volts for radios is much easier. As a reminder, don't strike an arc about any cell that is gassing or one might explode a cell. :-)

Thrush's picture

If you have a 12V lead acid bank of batteries, in another room or area you can place a 24V Nickel Iron bank to 'piggy back' and maintain the quality of the lead acid bank. Just tap off from the 24V bank what you need to keep the lead acids at 12.6 V. When the Nickel Iron bank reaches a full charge and the lead acids are also charged add a diversion load like a well pump or hot water heater element to th 24v bank. Having both 12v and 24v inverters add redundancy. When running short of power on a cloudy day add in extra panels and throw all the power into the 12v bank :-)

Michael Welch's picture

Hi Thrush. I guess I do not understand why one would want to do this. It sounds expensive and a hassle. There's a lot to be said for keeping things simple and straightforward.

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