AGM vs gel battery - choose the best fit for your application

Batteries are very crucial in our day-to-day living, they are used for commercial and home. Someone select the AGM as a trolling battery, and others opt for gel batteries for their use, but how many know the differences between the two and their usage? This article will provide you an all-round comparison about AGM vs gel battery, to help you understand the difference between the two more deeply.

1.What is an AGM battery? Is AGM considered to be sealed or gel?

AGM battery is an ultra-fine glass fiber battery, which is a valve-regulated sealed lead battery using a glass fiber separator (AGM), so it is considered to be sealed and belongs to a type of VRLA battery, while gel battery is another type of VRLA battery. The AGM battery uses a pure sulfuric acid aqueous solution with a density of 1.29-1.3lg/cm3 as the electrolyte.

Most of the electrolyte exists in the glass fiber membrane, and a part is absorbed inside the electrode plate. In order to provide the channel to the anode for the oxygen precipitated by the cathode, it is necessary to keep 10% of the pores of the separator not occupied by the electrolyte, that is, the lean liquid design.

2.A guide to the AGM battery

① What is the advantage of an AGM battery?

AGM batteries are known to have relatively medium internal resistance. This means AGM battery has low opposition to the currents produced by the cells and the battery, leading to heat production. Due to these characteristics and advantages, AGM batteries can deliver high currents when needed. This energy is used in starting up the ignition systems of cars and trucks. This balance between internal resistance and heat generation enables the battery to have a long lifespan.

In addition, AGM batteries have higher capacity stability over the entire life cycle than ordinary lead-acid batteries. Despite this, the cycle life of AGM batteries is still far less than that of lithium-ion batteries. The cycle life of lithium-ion batteries is as high as 4,000 times, while the number of cycles of AGM is only 1,000 times, and its charge retention ability is not as strong as that of lithium-ion batteries.

② What is the main disadvantage of an AGM battery?

AGM sealed lead-acid batteries have less electrolyte, thicker plates, and lower active material utilization than open-type batteries, so the discharge capacity of the battery is about 10% lower than that of open-type batteries. Compared with the gel-sealed battery, its discharge capacity is smaller.

AGM batteries are more sensitive to charging voltage, so if the AGM batteries are overcharged, their battery life will be shortened or even the AGM batteries may fail. In addition, AGM batteries are not resistant to high temperature. If they are placed in a high temperature environment for a long time, the life of AGM batteries will be seriously reduced.

③ Does an AGM battery need a special charger?

AGM battery does not require a special charger because it has no special requirements for the charger. It can be charged with a normal charger, but the voltage and current must be adjusted when charging, otherwise the battery will be damaged. Therefore, it is better to provide a smart charger that can charge intelligently. 

High-quality chargers are required here, especially from the battery store that manufactures this battery. When charging the AGM battery, it is recommended to use a 14.4V constant voltage current limiting charger for charging, and the maximum charging current should not be higher than 30A.If the charging voltage is higher than 14.8V, it may affect the stability of the batteries in the future and hence impacting the life span of the same batteries.

④ Do AGM batteries fail suddenly?

From time to time, the AGM batteries may fail. The high temperatures of the surrounding may cause the failure. The high temperatures will drain off the electrolyte in the vessel; when drained off, the battery fails, and death of the same is easy. Again incorrect charging may lead to continuous death, especially when the battery is connected to high voltage power. Charging at too high a voltage accelerates corrosion and increases the rate of self-discharge

⑤ How do you maintain an AGM battery?

The general rule for maintaining the AGM battery is to store it in a cool, dry, and well-ventilated environment. It is also important to remember to recharge, especially if you are storing for a long period. This act eliminates the slow death of the batteries, which may occur when recharging is ignored.

3.Is an AGM battery the same as a gel battery? How do I know if I have an AGM or gel?

4.Frequently Asked Questions about the gel battery

① How many years will a gel battery last?

The life of the gel battery needs to be based on specific conditions. One is the applicable environment. If the ambient temperature is high, generally speaking, based on 25 degrees, its life will be reduced by half for every 10 degrees. Another is the charging conditions. If the gel battery is often undercharged, the battery will soon fail, and the charging capacity of a single cycle should be more than 1.2 times the discharge capacity.

In addition, the depth of discharge of the battery will also affect the service life of the gel battery.Under the premise of charging and discharging once a day on average and only releasing 30% of the actual capacity of the battery each time, the number of cycles of the gel battery is more than 1500 times, which is about 4 years (1500/369≈4.06).

However, if the DOD is 80% each time, its life span is only more than one year, and if the DOD reaches 100%, its life span is only about one year. It is worth noting that under the same condition of charging and discharging once a day on average, the cycle times of best lithium batteries is as high as 4,000, that is, 10 years (4000/369 ≈ 10.96), which is much longer than the service life of gel batteries.

② Can you charge a gel battery with a AGM charger? Why do gel batteries need a special charger?

You can’t charge a gel battery with an AGM charger. The gel battery will not fully charge, which may damage the battery slowly. Gel batteries on an average rate of 14.4v, slightly lower than AGM. Exceeding this may cause bubbling of the electrolyte, and permanent damage may occur. This is the reason why gel batteries need a special charger. We can sum this up as AGM vs gel battery as normal charger requirement vs special charges requirements, respectively.

③ The pros and cons of a gel mat battery

Gel mat batteries have a longer lifespan in extreme conditions. This is the opposite of the AGM batteries, which are volatile in extreme conditions. They are also easy to maintain, as hydrogen gas is evolved when they are charging, this helps in safeguarding the plates from corrosion. Indeed, the maintenance of AGM vs gel battery is labor intensive and less intensive, respectively. However, gel batteries require special chargers and regulators. if normal chargers are used, there will be damage to the cells.

④ Can I add distilled water to a gel battery?

No. Gel batteries do not require distilled water as the cells are sealed off.

⑤ How do you revive a dead gel battery?

Gel batteries cannot be revived; however, with proper recharging, they can serve you for a few months even though cold weather conditions will corrode them fully.

5.AGM vs gel battery, which is right for you?

When comparing AGM vs gel battery, which one to choose is a thoughtful question, which need to consider many factors. You can refer to the information below  to decide which one is the right one.

① Can a battery be both AGM and gel?

This is quite difficult as the battery incorporations differ; AGM vs gel battery are silica and gel paste, respectively.

② What are the major differences between AGM vs gel battery?

There are several key differences that distinguish AGM vs gel battery, they are both internal and external. The acids in an AGM battery are absorbed by the glass mat, while in gel, it is mixed in the electrolyte to form a chemical reaction. Secondly, when comparing low temperature performance of AGM vs gel battery, the latter is better than the former. Thirdly, the AGM battery is expensive to maintain, while the gel needs to be recharged and stays for months; other differences between AGM vs gel battery are summarized below:

③ Which is better AGM battery or gel battery?

A comparative analysis of AGM vs gel battery is made above, and their working principles, their advantages and disadvantages, as well as the differences between the two are introduced in detail. Generally speaking, these two types of batteries are suitable for different application scenarios due to their characteristics. According to your usage requirement, choose the most suitable one between AGM vs gel battery, which is the best for you.

Related article: agm battery vs flooded, gel battery vs lead acid