How to maximize the lifespan of your AGM deep cycle battery
This is by far the most common question that we get asked by boat owners, electric scooter enthusiast, and electric wheel chair owners. Deep cycle batteries come in several different group sizes, terminal configurations, and chemistry depending on the application that they are used for. We specialize in 12V AGM deep cycle batteries so I will be referencing this throughout the guide however this article will still apply to flooded conventional style as well.
Cycle Life: Don’t run your batteries into the ground every time
All deep cycle batteries regardless of chemistry will have a set amount of charge cycles in which it is rated to perform at its optimum level. If you take a look at figure 1 below you will see the cycle life performance and expectancy for our EVH12390 - a 12V 39AH U1 battery.
The first thing that you will notice is that there are three separate possible cycle lifespans shown on the graph each with a different depth of discharge. For a deep cycle battery the depth of discharge will be how much of the reserve capacity has been spent or taken from the battery. So the first line on the graph going from left to right reflects a 100% discharge of the battery every single cycle. In other words the deep cycle battery is run all the way down and charged all the way up for every cycle until it reaches the end of life expectancy at the 300 cycle mark.
We always recommend to all of our customers looking to maximize their battery lifespan to not run their batteries all the way down every time if it can be helped. The less capacity used in the battery prior to charging back up will greatly improve the cycle life of the battery which is depicted in Figure 1 by the second and third lines.
Proper Charging and Storage Practices
The number one reason for early deep cycle battery failure is sulfation. Sulfation occurs when the battery is left in a discharged state for a brief (one week) to a long (several months) period of time. Essentially what happens is that when the battery is being drained the lead sulfate converts to a stable crystalline which then deposits on the negative plates of the battery. This process is reversed when the battery goes into a charge cycle. The longer the battery sits in a discharged state with these crystalline deposits, the harder they become on the plate which in turn makes them more difficult to remove.
The solution to prevent sulfation from occurring is to keep your deep cycle battery in a charged state. That means charging your deep cycle battery after every use. If you have an application that is stored during the winter months - i.e. boats and electric scooters - then ideally you would have an automatic battery maintainer to keep them topped off until the next season. If you do not have a battery maintainer then it is recommended to pull the batteries out of storage once every two months and place them on charge. Deep cycle batteries are capable of retaining a charge for roughly three months of inactivity, putting them on charge every two months will ensure that sulfation does not have an opportunity to set in.
What is a GEL Battery?
Two of the most common terms that we hear from customers are AGM and GEL, which are often mistaken for the other more than half the time. We have already explained what exactly an AGM battery is, now we will be taking a look into what sets a true GEL battery apart from the rest of the sealed lead acid pack.
Okay, first and foremost, the term GEL is short for gelified electrolyte lead acid. In other words, a true GEL battery will actually contain a gelatin in place of the typical free flowing electrolyte (battery acid). A special gelling agent is added to the electrolyte to reduce the movement of acid inside of the battery – the process literally turns the acid mixture into a gooey Jell-O like substance. Due to this mixture of Jell-O like acid, the GEL battery is designed with special one way safety valves in place of open vents typically found on wet-cell batteries (non-sealed), this method of venting allows the internal gasses to recombine back into water in the battery, greatly reducing gassing.
Is the GEL Battery Sealed?
Yes, the GEL battery is a sealed non-spillable type. If the casing of the battery were to develop cracks or otherwise be compromised, there will be no free flowing acid leaking out the of the battery.
Is it Maintenance Free?
Yes, the GEL battery is also a maintenance free type. The term battery maintenance typically refers to the need to check on the electrolyte level of the battery about every thirty to sixty days depending upon usage. The valve system used in both AGM and GEL applications minimizes the amount of electrolyte released from the battery during the charging period.
What is a GEL battery used in?
The GEL style battery is used in wide variety of deep-cycle applications due to their ability to recover from deep discharge cycles. Where the GEL battery will excel is in situations that require a slow and steady discharge. A prime example of a good application for a GEL battery would be an electric mobility chair.
What is a Sealed Lead Acid Battery?
The sealed lead acid battery is by far one of the most popular batteries that we receive questions on here at High-Tech Battery. I have decided (finally) to post a few of the most common questions that I hear from customers regarding sealed lead acid batteries here in our Battery Information Center, so here it goes.
What exactly is a sealed lead acid battery?
A sealed lead acid battery is what is originally known as a VRLA battery, or a valve regulated lead acid battery. These batteries are a 100% rechargeable, and based off a lead acid design. These batteries are designed to be maintenance free (do not require the user to add water to the cells), and spill proof. These batteries can be mounted in any position and still operate to their full capacity without spilling a drop of acid.
You may be wondering where exactly the valve regulated part of the sealed lead acid battery comes into play. Every SLA (sealed lead acid) battery is designed with a special safety release valve. These valves act as a emergency pressure release system that activate to alleviate the build up of gases within the SLA battery. During a period of an extremely high rate of charge (extreme over-charging), gases will be generated inside the battery that could potentially build up to critical levels and force its way out - via exploding a side of the battery out, or a simple crack in one of the cell dividers. To prevent this from happening, all SLA batteries are designed with these small pressure release valves.
Are there different types of sealed lead acid batteries?
Yes, there are two different types of SLA batteries out on the market today - AGM, and GEL batteries.
AGM batteries utilize a special plating process which optimizes the effectiveness of electrolyte reaching the batteries lead plates. AGM stands for absorbed glass mat, which is essentially what the entire process consists of. A mat consisting of very thin glass fibers woven together is placed between the internal lead plates of the battery. This glass mat is capable of absorbing and holding the optimum amount of electrolyte between the plates for the lifetime of the battery. This technology cuts down on the use of electrolyte and increases the efficiency and power of the battery.
The infamous GEL battery (confused with AGM SLA batteries on a daily basis) utilize a special gel based mixture between the plates of the battery instead of the typical electrolyte found in the common flooded lead acid batteries (think car battery). In this case, the gel is a combination of silica fume and standard sulfuric acid to create a type of gelified electrolyte. This design enables the battery to suffer much less internal corrosion, thus increasing the overall life of the battery - assuming you take care of it properly
What is an AGM Battery?
The term AGM is short for Absorbed Glass Mat, which is a specific manufacturing process utilized in the production of sealed lead acid batteries (SLAs). In the AGM manufacturing process, extremely thin glass fibers are woven together to form a glass mat separator that is placed between each lead plate. The glass mat plates allow for the even distribution of electrolyte over the entire surface area of its adjacent lead plate(s) due to its ability to hold acid. This maximization of electrolyte to plate coverage enables these batteries to far exceed the performance of conventional flooded lead acid batteries.
