PowerStar® Brand AGM Sealed Lead Acid Batteries
A newer type of sealed battery uses "Absorbed Glass Mats", or AGM between the plates. This is a very fine fiber Boron-Silicate glass mat. These type of batteries have all the advantages of gelled, but can take much more abuse. AGM batteries. These are also called "starved electrolyte", as the mat is about 95% saturated rather than fully soaked. That also means that they will not leak acid even if broken.
Nearly all AGM batteries are "recombinant" - what that means is that the Oxygen and Hydrogen recombine INSIDE the battery. These use gas phase transfer of oxygen to the negative plates to recombine them back into water while charging and prevent the loss of water through electrolysis. The recombining is typically 99+% efficient, so almost no water is lost.
The charging voltages are the same as for any standard battery - no need for
any special adjustments or problems with incompatible chargers or charge
controls. And, since the internal resistance is extremely low, there is almost
no heating of the battery even under heavy charge and discharge currents. The
Concorde (and most AGM) batteries have no charge or discharge current limits.
Low Self Discharge
AGM's have a very low self-discharge - from 1% to 3% per month is usual. This means that they can sit in storage for much longer periods without charging than standard batteries. The Concorde batteries can be almost fully recharged (95% or better) even after 30 days of being totally discharged.
AGM's do not have any liquid to spill, and even under severe overcharge conditions hydrogen emission is far below the 4% max specified for aircraft and enclosed spaces. The plates in AGM's are tightly packed and rigidly mounted, and will withstand shock and vibration better than any standard battery.
AGM batteries main advantages are no maintenance, completely sealed against fumes, Hydrogen, or leakage, non-spilling even if they are broken, and can survive most freezes.
All Lead-Acid batteries supply about 2.14 volts per cell (12.6 to 12.8 for a 12 volt battery) when fully charged. Batteries that are stored for long periods will eventually lose all their charge. This "leakage" or self discharge varies considerably with battery type, age, & temperature. It can range from about 1% to 15% per month. Generally, new AGM batteries have the lowest, and old industrial (Lead-Antimony plates) are the highest. In systems that are continually connected to some type charging source, whether it is solar, wind, or an AC powered charger this is seldom a problem. However, one of the biggest killers of batteries is sitting stored in a partly discharged state for a few months. A "float" charge should be maintained on the batteries even if they are not used (or, especially if they are not used). Even most "dry charged" batteries (those sold without electrolyte so they can be shipped more easily, with acid added later) will deteriorate over time. Max storage life on those is about 2-3 years.
Batteries self-discharge faster at higher temperatures. Lifespan can also be seriously reduced at higher temperatures - most manufacturers state this as a 50% loss in life for every 15 degrees F over a 77 degree cell temperature. Lifespan is increased at the same rate if below 77 degrees, but capacity is reduced. This tends to even out in most systems - they will spend part of their life at higher temperatures, and part at lower.
Wet Cell (flooded), Gel Cell and Absorbed Glass Mat (AGM) these are various versions of the lead acid battery. The wet cell comes in 2 ways, serviceable (removable vented caps) and maintenance free, both are filled with electrolyte and I prefer one that I can add water and check the specific gravity of the electrolyte with a hydrometer. The Gel-Cell and the AGM batteries are specialty batteries that typically cost twice as much as a premium wet cell. However they store well and do not tend to sulfate quite as fast as wet cell. Most Gel-Cell and some AGM batteries require special charging rate, especially the deep cycle models. I personally feel that careful consideration should be given to the AGM battery technology. Gel-Cell batteries still are being sold but the AGM batteries are replacing them in many cases. There is a little confusion about AGM batteries because different manufactures call them different names; a couple popular ones are regulated valve and dry cell batteries. In most cases AGM batteries will give a longer life span than a wet cell battery, but will not stand up as well to hot temperatures and high discharge load.
Well these are the standards that most battery companies use to rate the output and capacity of a battery.
AGM when referring to batteries stands for Absorbed Glass Mat. This best describes their construction. AGM batteries still have lead plates within them, but the difference lies in the construction of the plates and the way the electrolyte is exposed to the plates. Simply put, the electrolyte is absorbed into finely woven Boron-Silicate glass fibre mats. These saturated mats are then placed between the plates. To see some battery comparisons take a look on my website shown below in the resource box. So what are some facts about AGM batteries when considering their use as camping batteries?
PowerStar battery general
features Sealed Construction
PowerStars's unique construction and sealing technique ensure that no electrolyte leakage can occur from the terminals or case of any PowerStar battery. This feature insures safe, efficient operation of PowerStar's batteries in any position. PowerStar batteries are classified as "Non-Spillable" and will meet all requirements of the International Air Transport Association.
Absorptive Glass Mat System (AGM System)
PowerStar batteries make use of fine mat separators (glass fiber) wherein suffient electrolyte is absorbed to provide the longest life and steady serive. This system prevents escape of electrolyte from the separator which causes leakage.
PowerStar batteries incorporated unique design that effectively controls generation of gas and allows recombination of over 90% of gas generated during the normal use.
During the expected floating service life of PowerStar batteries, there is no need to check the specific gravity of the electrolyte or add water, which means they require no maintenance service.
In fact, there is no provision for these maintenance functions.
Position-Free and Leakage-Free
The combination of the sealed construction and the use of absorptive mat separators permit operation off PowerStar batteries in any position without loss of capacity, electrolyte and service life. PowerStar batteries are made to operate in any position.
Stable Quality & High Reliability
The PowerStar SLA battery has stable and reliable performance. It can be easily maintained to permit proper operation of the equipment that it powers. The battery can withstand overcharge, over discharge, vibration, and shock, and is capable of extended storage.
Long Service Life, Float or Cyclic The PowerStar SLA battery has long life in float or cyclic service. The expected life of float service is shown on Figure10 and life of cyclic service figure 11.
Low Pressure Venting System
PowerStar batteries are equipped with a safe, low-pressure venting system which operates at 1psi to 6psi, designed to release excess gas and reseal automatically in the event that gas pressure rises to a level above the normal rate. Thus, there is no excessive build up of gas in the batteries. This low pressure venting system, coupled with the extraordinarily high recombination efficiency, make PowerStar batteries the safest sealed lead-acid batteries available.
The heavy-duty lead calcium-alloy grids in PowerStar batteries provide an extra margin of performance and service life in both float and cyclic applications, even in conditions of deep discharge.
Low Self Discharge
Because of the use of Lead Calcium grids alloy, PowerStar SLA battery can be stored long periods of time without recharge.
High Recovery Capability
PowerStar batteries have an excellent charge acceptance and recovery capability even after deep discharge.
U. L. Component Recognition
AII of our PowerStar SLA batteries have already passed UL