Gel Battery 101: Definition, Pros and Cons & Applications

The lead-acid battery technology has come a long way and evolved for more than 150 years, allowing the creation of high-quality and durable sealed lead-acid batteries like the gel cell battery. Nowadays, gel batteries have multiple applications, such as UPS devices, wheelchairs, RVs, motorcycles, and many others requiring a deep-cycle battery with a long life span.

Gel cell batteries are made using a battery technology known as valve-regulated lead-acid (VRLA) or sealed lead-acid (SLA) battery. This is a zero-leakage technology that requires little or no maintenance. These batteries are resistant to vibrations and shocks, can be installed in multiple positions, and are ideal for most recent applications due to their excellent price and performance.

While the gel cell battery is the best option for most applications, it is essential that you truly understand it and its functioning. This article aims to cover all the basics and a little more, including what gel batteries are, their advantages and disadvantages, and how they compare against other technologies. We even have a gel battery review section with the best gel battery for each application.

What Are Gel Batteries and How Does It Work?

To learn the basics of gel batteries, it is essential to answer the big questions: What are gel batteries, and how do they work? This might seem pretty complex, but in truth, it is pretty easy to understand. Here, we will explain to you everything about this battery and its internal working process.

What Are Gel Batteries?

To understand what a gel battery is, you need to know that there are several types of lead-acid batteries. The first lead-acid battery was the wet cell lead-acid battery, an outdated and more straightforward lead-acid technology still used today. After many improvements, the SLA/VRLA technology appeared on the market.

Wet cell batteries used an openly vented liquid electrolyte that could easily spill, which restricted the battery to be placed in a specific position and release hydrogen gas when charging. The use of SLA technology improves and even eliminates these significant issues. Presently, there are two primary types of SLA batteries: AGM batteries and gel batteries – the latter is the one we are talking about.

The gel battery is an SLA battery that uses a gelled electrolyte requiring little or no maintenance. This better-engineered battery is stable and ensures a longer life span, delivering up to 500–1500 cycles for an 80% depth of discharge (DOD) or more at the recommended 50% DOD.

How Does a Gel Battery Work?

To understand what a gel battery is, you should realize its inner functioning on a superficial basis. This battery works similarly to other batteries by working as a charged energy block and can then be connected to a load to supply electric power. Gel batteries can be discharged to a 75–80% DOD, but this can reduce the battery’s life span, which is why most manufacturers recommend a 50% DOD. 

Gel batteries have a thick or gelled electrolyte made out of diluted sulfuric acid combined with pyrogenic silica, which turns the electrolyte into a gel-like substance that is relatively stationary. This prevents electrolyte spillage and electrolyte evaporation and reduces battery corrosion.

For the terminals and inner grid, gel cell batteries use lead-calcium plates instead of the classic lead-antimony plates used for antique lead-acid batteries. The addition of lead-calcium plates allows for hydrogen reabsorption and reduces water consumption, which is why gel batteries require little to no maintenance and have a low self-discharge rate.

An electrochemical process occurs between the electrolyte and the plates when the gel battery is charged or discharged. When discharging, negatively charged electrons flow through the circuit to deliver electricity to the load. The opposite process occurs when the battery is being charged back up again. Meanwhile, the electrolyte works as a medium for the flow of positive ions that work in a balanced process.

What Are the Advantages and Disadvantages of Gel Batteries?

Gel batteries are robust and reliable. This technology presents many advantages with very few disadvantages. Here, we go over the most critical gel battery advantages and disadvantages to understand this technology deeper.

Advantages

Here are several advantages of gel batteries.

1. SLA/VRLA Technology (Spill-proof and Maintenance Free)

One of the best gel battery advantages is the use of sealed lead-acid or valve-regulated lead-acid technology. This technology allows for installation in multiple positions, reduces maintenance requirements, and is much safer since it eliminates the hydrogen gas released when charging.

2. Very Low Self-discharge Rate

Gel batteries have a meager self-discharge rate. This is achieved by including lead-calcium plates and a high-purity gelled electrolyte that reduces water losses, ensuring you can store batteries for more extended periods without regularly checking charge levels.

3. More Life Cycles than Any Other Lead-Acid Battery

The gel cell battery uses better-engineered technology that ensures a longer life span. These batteries can deliver up to 500–1500 cycles at an 80% DOD for a 10–20-year life span.

4. Better Investment in the Long Run

Gel cell batteries have a high initial cost, but they also have many more cycles. This excellent cost-cycle relation for Gel batteries makes for a better investment than for other lead-acid batteries.

5. Resistant to Vibrations and Shocks

The gel cell battery has a gelled electrolyte that is relatively solid, meaning that the battery can be transported or placed in vehicles without vibrations or shocks, representing an inconvenience.

Disadvantages

Here are several disadvantages of gel batteries.

1. Expensive Technology (High Initial Cost)

Gel batteries tend to cost a few more bucks than flooded or AGM batteries. In some cases, this initial cost can discourage battery users, but the simple conclusion is that gel batteries are a significant investment when comparing the cost-cycle relation.

2. Sensitive to Overcharging (Requires Special Chargers)

Overcharging a gel cell battery creates empty holes or voids in the gel that reduce the battery’s overall capacity. Overcharging can also inflate the positive lead-calcium plates due to grid oxidation.

3. Lower C-Rates

Gel batteries have a design that requires charging and discharging at a lower rate than other lead-acid batteries. This is why we recommend using these batteries for loads requiring stable mid-low amps for extended periods.

Differences Between AGM Batteries and Other Types of Batteries

Understanding the differences between gel batteries and AGM, flooded, and other batteries ensures you know which battery technology is the best for you. Here, we will compare gel vs. AGM, wet cell, regular, and lithium batteries, considering technology, price, dimensions, weight, performance, and others.

Gel vs. AGM Batteries

Both AGM and gel cell models use SLA battery technology, ensuring no electrolyte leakage, reducing maintenance requirements, and allowing for installation in multiple positions. Both batteries differ in weight and size since gel cell batteries are bulkier and up to 20–30% heavier than AGM.

One significant difference between the AGM and gel batteries is how they hold the electrolyte. AGM batteries have the sulfuric acid electrolyte between absorbent glass mat separators, while gel batteries combine it with silica ultrafine powder to form a gelled electrolyte.  

The gel cell battery handles lower C-rates, making it a better fit for low-current-demanding applications, while the AGM battery can deliver high currents on demand. Gel batteries also have to be charged and discharged at lower rates than AGM batteries.

A 12V AGM battery provides adequate performance in cold climate weather, while most gel batteries have lower performance. The contrary happens in hot climates, where a 12V gel battery excels compared to AGM, especially since AGM batteries can be prone to thermal runaway.  

Another significant difference between the AGM and gel batteries is the price. A 12V AGM battery is cheaper and delivers up to 200–500 cycles at an 80% DOD, lasting 5–10 years. Gel batteries require a slightly higher initial cost, but they last for up to 10–20 years and deliver 500–1500 cycles at an 80% DOD, making them a better investment in the long run if applicable.

Gel vs. Flooded Batteries

Both gel and flooded batteries use a lead-acid electrolyte, implementing different technologies. Gel batteries use SLA/VRLA technology with a gelled electrolyte, while the wet cell battery uses an openly vented sulfuric acid electrolyte. Unlike gel batteries, the wet cell battery requires regular maintenance, releases hydrogen gas when charging, and has to be placed upright at all times.

The size and weight highly differ when comparing a gel battery vs. a lead-acid, flooded battery. Gel cell batteries are compact and lighter, 50% lighter than flooded batteries with the same capacity.

The electrolyte within gel cell batteries is delicate and can only handle low C-rates, making for a better deep-cycle battery. On the other hand, flooded batteries can be designed as a starter or deep-cycle batteries supplying high currents on demand. While both batteries can be discharged at different rates, they have to be charged at the same speed to avoid the excess release of hydrogen gas for flooded batteries.

Neither flooded batteries nor most gel batteries are a good fit for cold climates since both electrolytes struggle to provide a charge and lose part of their charged capacity in the process. In hot environments, gel batteries perform better than flooded ones and do not require regular maintenance when stored.

Flooded batteries are much cheaper than gel ones, but gel batteries make for a better investment. Gel batteries indeed have a high initial cost, but they can last up to 10–20 years in delivering 500–1500 cycles at an 80% DOD, while flooded batteries barely last 3–5 years and deliver only 500 cycles at a 50% DOD.

Gel vs. Regular Batteries

There are many differences between gel and regular batteries – the first one being its technology. Gel batteries use SLA technology with a gelled electrolyte made out of sulfuric acid and silica, while standard batteries have diluted sulfuric acid for their electrolyte. Regular batteries require constant maintenance and can only be installed upright. They also release hydrogen gas when charging.

One significant difference between gel and regular batteries is their applications. Gel deep-cycle batteries are used to power low-to-medium amp loads for long periods to a 50–80% DOD, delivering up to 500–1500 cycles. Regular batteries are starter batteries delivering high cranking amps for a few seconds to 95–98% DOD starting cars, boats, and many vehicles. When standard batteries are deep cycled to a 50–80% DOD, they barely last 30–150 cycles, delivering more than 1000 cycles when adequately discharged.

While both gel and regular batteries are usually charged at a relatively low amp rate, starter batteries can withstand high charge and discharge currents. Meanwhile, this practice would damage the gelled electrolyte. Both batteries perform poorly at low-climate temperatures, but gel batteries withstand better hot temperatures than regular batteries.

Gel technology has a higher energy density, so gel batteries are more compact and lighter than regular batteries.

Gel batteries have high initial costs, but they deliver 500–1500 cycles and can last 10–20 years, depending on the deep-cycling applications. Regular batteries are usually cheap and are only used to start cars, trucks, boats, and other devices, lasting for 3–5 years.

Gel vs. Lithium Batteries

Lithium and gel batteries are so different that they do not even share the same chemical compound for the electrolyte. Gel batteries use a gelled sulfuric acid electrolyte, while lithium batteries use lithium salts dissolved in organic solvents for their electrolyte. Both batteries require little to no maintenance and can be placed in multiple positions.

Since lithium batteries tend to have a higher energy density, they can be used for many more applications, which is why they are the preferred choice for cell phone batteries, other small devices, and several deep-cycle applications. Gel batteries are bulkier and heavier than lithium ones, which is why they are only ideal for stationary deep-cycling applications and vehicles like boats, motorcycles, and more.

Both batteries can handle slightly different currents. Lithium batteries operate at high C-rates, which is why they can be charged and discharged at a faster rate and deliver high currents on demand. On the other hand, gel batteries handle low C-rates and can be charged and discharged at lower amps.

While some gel batteries perform poorly at low temperatures, lithium models have extremely low performances at temperatures below 50ºF. Gel batteries can perform relatively well at high temperatures, while lithium batteries have excellent performance at low temperatures.

Gel batteries deliver 500–1500 cycles for a life span of 10–20 years and are an excellent investment in the long run. On the other hand, lithium batteries can last for 20 years or more, delivering up to 2000 cycles, but they have a much higher cost, which is why they are considered the premium ones. 

Best Gel Batteries

When reviewing different battery types for the most popular applications, we found several gel batteries with excellent performances and great cost relations. This section brings you our top picks for gel batteries for each of the most popular applications.

1. CB YTX12-BS iGel Motorcycle Chrome Battery – Best Gel Motorcycle Battery

When researching batteries to find the best options for our top motorcycle batteries article, we went through several lithium, gel, and AGM batteries. Considering performance, C-rate, price, and more, the irrefutable winner as the best gel motorcycle battery is the Chrome YTX12-BS battery.

The YTX12-BS is a 12V gel battery with a designed capacity of 10 Ah and a reserved capacity of 15 min. The battery can supply starting currents of up to 250 cranking amps (CA) or up to 180 CA at a 0ºF temperature for 30 seconds (CCA), quickly starting any motorcycle engine in different climates. 

The battery’s casing includes a monitor that allows you to check the remaining capacity, voltage, and other specifications. With dimensions of 5.91 x 3.43 x 5.12 in. and a weight of 8.46 lbs., this battery will perfectly fit any motorcycle without compromising balance or performance.

If you want to check out other battery models we have reviewed, be sure to check out our article about the top motorcycle batteries. There, you will find many more options to suit your motorcycle needs.

2. Weize 12V 100AH Pure Gel Deep-Cycle Rechargeable Battery, for Solar Power System RV House Trolling Motor Wheelchair, Universal – Best Gel RV Battery

RVs require reliable batteries that provide enough energy to power most devices and ensure a longer life span. Our top RV batteries review article reviewed some of RVs’ best lithium, gel, and AGM batteries. There, you will find the best performance batteries for a reasonable price.

After reviewing these batteries, we selected the Weize LFP12100 (12V 100AH/10H) as our top pick gel battery for RVs. This is a high-capacity battery of 100 Ah with a C10 C-rate, providing your RV with a stable and constant current of 10 amps for up to 10 hours. This battery can deliver its total capacity or more at 77ºF–104º F, while at low temperatures, it can supply up to 85% at 32ºF and 65% at 5ºF.

This RV battery can be discharged at 5ºF–12ºF and charged at 14ºF–122º F. The manufacturer recommends storing this battery at a temperature of -4ºF–122ºF, where you will get an average self-discharge rate of 5% for 3 months or 12% for 6 months.

3. Renogy Deep-Cycle Hybrid Gel 12V 100Ah Battery – Best Gel Marine Battery

Gel batteries are excellent for marine applications. These batteries withstand the constant vibrations of boats at sea and deliver enough energy to power low-amp devices installed on boats.

Our pick for the best marine battery with gel technology is the Renogy Hybrid Gel 12V 100Ah/20Hr. With an installed capacity of 100 Ah and a C20 C-rate, this battery can deliver 5 amps for up to 20 hours. You can get a max surge current of up to 1000 amps for 5 seconds, but this regular practice can damage the electrolyte and reduce the adequate energy capacity that the battery has at such a high amp rate.

The Renogy battery is recommended to be operated at 68ºF–86ºF, but you can discharge it at -4ºF–140º F and charge it at 32ºF–122ºF. This battery can be stored at a -4ºF–140º F temperature, where you can expect a monthly self-discharge rate below 3% at 77ºF. This battery can be discharged up to 100% of its capacity, but it will shorten its cycles to 300 while using a 50% DOD will ensure more around 700–800 cycles, or you can even get up to 1500 cycles at a 30% DOD.

If you want to check out more about this battery and other available options, you will find the best-known models in our top best marine batteries reviews article.

4. ML35-12 Gel – 12 Volt 35AH Rechargeable Gel Type Battery v Mighty Max Battery Brand Product – Best Gel Golf Cart Battery

Golf carts require reliable batteries that deliver low to medium amps for long periods. In our top golf cart batteries reviews article, we do an in-depth analysis of the best batteries available for golf carts. There, you will find excellent performance batteries at low prices.

We picked the MightyMax ML35-12 gel golf cart battery from all of the reviewed batteries as our favorite. This 35 Ah capacity battery with a C10 C-rate can deliver 3.5 amps for 10 hours, 3.7 amps for 20 hours, or up to 20 amps for 1 hour. You can also get 330 amps for 5 seconds, but this practice will rapidly reduce the battery’s life span.

The MightMax battery operates at a 5ºF–104º F temperature. The battery can deliver 100% of its capacity at 77ºF–104ºF or a reduced ability of 65% for cold climates of 5ºF. When storing this battery at 68ºF, you can expect a self-discharge rate of 10% every 3 months.

5. Gel Cell Deka 8G27 Gel Battery – Best Gel Solar Battery

Gel solar batteries should charge with solar panels and withstand deep cycling when delivering low to medium currents, depending on the home requirements. When reviewing the best options for our top solar batteries article, we picked the Deka 8G27 battery as our favorite gel solar battery.

The Deka 8G27 battery has a designed capacity of 88 Ah at a C20 C-rate, delivering 4.4 amps for 20 hours, but it can go as high as 20 amps for about 4 hours. This battery works best at 77ºF–95º F, and it can never exceed 105ºF. The Deka 8G27 should be stored at 0ºF–90º F and for no more than 12 months. This battery can deliver up to 500 cycles at 80% DOD or 100 cycles at 50% DOD.

If you want to know more about these and other batteries for solar systems, check our top solar batteries reviews article, where we do an in-depth analysis of the best solar batteries available.

6. Best Gel Truck Battery

Batteries for trucks should be coupled considering the battery size by how many CCA it can deliver concerning the engine displacement in cubic inches. This means that the larger the truck engine, the higher the starting current you require from a battery.

On average, regular truck engines require starter batteries to deliver up to 400–500 CCA and a high peak current of 400–500 cranking amps at 0ºF for about 30 seconds. Some bigger engines can even demand starting currents of 700–1000 CCA.that

Unfortunately, a gel cell battery cannot handle these high currents due to its gelled electrolyte. Other technologies can provide these cranking amps, like AGM and lithium. In our top truck batteries reviews article, we analyzed and reviewed the best truck batteries available. Here, you will be able to find an excellent truck battery for a reasonable price.

7. Renogy 12V 200Ah Rechargeable Deep Cycle Hybrid Gel Battery – Best Gel Trolling Motor Battery

Angling is fun and can give you some peace of mind, but to truly enjoy it, you must have a reliable battery to start your angling boat and power-installed devices. After reviewing many quality batteries for our top trolling motor batteries article, we picked the Renogy 200Ah/20Hr as the best gel trolling motor battery.

The Renogy battery has a designed capacity of 200 Ah at a C20 C-rate, delivering 10 amps for 20 hours, 18.6 amps for 10 hours, or up to 51.4 amps for 3 hours. It can operate at a temperature of -4ºF to 113º F, delivering around 60% of its capacity at -4ºF and beyond 100% of it at 113ºF.

This battery can last more than 500 cycles at 80% DOD and beyond 1000 cycles at 50% DOD. This battery has a shallow self-discharge rate below 2% when stored at a 77ºF temperature.

GEL Battery FAQs

To ensure you take good care of your gel cell battery and make the best out of it, it is essential to have the correct information. In this gel cell FAQ section, we answer some of the most common questions about gel batteries, where you will be able to solve any doubts and learn valuable information.

How Do You Charge a Gel Cell Battery?

It is essential to know how to charge a gel cell battery to take proper care of it. The charger voltage should be steadily increased until it reaches a maximum of 2.4 volts per battery cell. For instance, a 12V gel battery has six cells, so you need a max voltage of 2.4 x 6 = 14.4V to charge the gel battery.

You also have to compensate for the voltage per battery cell by 2.8 mV (0.0028V) for each Fahrenheit degree differing from 77ºF. This means that you have to increase the voltage for lower temperatures and decrease it for higher ones.

The maximum current when charging gel batteries is 10–13% of the C20 current, which is a current equal to one-twentieth (1/20) of the battery’s capacity. When charging gel batteries, ensure that the gel charger uses a profile that slightly decreases the current after reaching 80%. At the same time, it steadily increases the voltage until reaching that same capacity, as shown in the figure below. 

Can You Charge a Gel Battery with a Regular Charger?

Our readers have frequently asked us: Can you charge a gel battery with a regular charger? The truth is you cannot. Standard chargers allow you to set specific parameters, and they will charge the battery at that pace until it reaches 100%. They can also overcharge the battery.

A gel battery charger has microprocessors and sensors that generally monitor the battery capacity, temperature, and battery state. The gel battery charger has different charging profiles like the one shown in the question above, allowing you to charge the battery at the suitable parameter until fully charged.

What’s the Difference Between a Battery Cycle and a Battery Life Span?

There is a relatively simple difference between battery cycle and battery life span. The battery cycle is how many cycles you can get out of your battery, which is the number of times you can discharge a gel battery to a specific DOD and charge it back up again to its total capacity. The life span of a battery is how much time a battery can averagely last measured in years.

While the life span is more of a time reference concerning the standard usage of a battery, the battery cycle is a more precise measure. You can make a battery last more or less time in years, depending on what DOD you discharge it to, how often you cycle your battery (once or twice per day, once per week, etc.), and the average climate temperature at your location.

How Long Will My Gel Battery Last?

The life span of gel cell batteries depends on their design and the application you use them for. Gel batteries handle low C-rates, which is why to extend their life span, you should avoid demanding high currents and learn how to charge a gel cell battery at the recommended parameters by the manufacturer.

When calculating how long your gel battery will last, you should also consider the estimated cycles at a specific DOD and how often you discharge and charge it back again. After the estimated lifetime of a battery, this starts to regularly lose its capacity, allowing you to get some more cycles at a reduced capacity until you can no longer get more power out of it.

For instance, the Renogy 200Ah/20Hr battery lasts around 500 cycles at 80% DOD, while at 50% DOD, it ensures 1000 cycles. It is essential to keep in mind that while using a higher DOD translates into more energy per charge, it also means a shorter life span and number of cycles. On average, gel cell batteries last 500–1500 cycles for up to 10–20 years, but this can vary concerning how often you cycle a battery and what DOD.

Can I Use Gel Batteries for My Solar Panels?

Gel batteries are an excellent pair with solar panels for small solar systems and even off-grid homes. These batteries require little or no maintenance at all, are safe to use at homes, can supply energy for long periods, and the best thing is that they have more cycles which make for a better investment in the long run.

When coupling a gel cell battery bank with a solar panel system, installing a battery charge controller that ensures a longer battery life for your batteries is essential. This device will charge your batteries at the correct voltage/amperage with excess power generated by the panels to be used in cloudy weather or nighttime when the panels are not generating. You need your batteries at total power output.

How Do I Change My Gel Battery?

Changing a gel battery is relatively easy, but you should never forget safety precautions, like avoiding metal tools or even parts of your body from touching both battery terminals simultaneously. You can also wear isolating gear for safety precautions.

Whether you are changing a battery for a vehicle, battery bank, or another application, the disconnection/connection process is the same. Disconnect a battery by removing the negative and then the positive terminal, and connect the new battery by connecting the positive and then the negative terminal.

If you are changing a gel battery in a home backup energy storage system (battery bank), there are specific additional steps that you should follow. First, disconnect the breaker for the panels or wind turbines if you have some, then disconnect the breaker going from the load to the battery and wait for a couple of minutes. After some time, properly disconnect the old battery and connect the new one.

Remember to install negative to positive terminals for batteries in series or positive – positive and negative – negative for parallel batteries.

Conclusion

Gel cell batteries use powerful and versatile technology. These batteries can deliver low to mid currents, do not spill electrolyte, and can be placed in multiple positions. They are one of the leading options for many applications requiring batteries for low-amp demands with more life cycles.

While it is true that gel cell batteries present a higher initial cost than other lead-acid batteries when comparing the cost vs. cycles, the performance of gel batteries makes up for it. These batteries can be easily used for most applications requiring low amps like trolling motors, motorcycles, RVs, solar systems, UPSs, golf carts, and even marine applications.

Getting the right and best gel battery for you is a matter of considering what application you need it for and making the right choice. In our best gel batteries section, you will find the most outstanding gel batteries for popular applications that excel in performance, price, and more. In this section, you can check our reviews articles to find other suitable batteries for you.

When discharged and charged at the proper parameters, gel batteries can last for many years and be an extremely loyal ally. Check out our FAQ section if you have any doubts about charging your batteries, what type of charger to use, and even how to change a battery. The information in there will help you make the best out of your gel battery to extend its life span for years. 

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