What Is A Gel Battery?

Today on Off Grid Power Geek, we’ll be talking about: ‘What is a Gel battery?’.

We’ll answer that, and look at their advantages and disadvantages.

We’ll go on to tell you why they were needed, as a solution to the problems of traditional lead acid batteries.

Not only that, we’ll discuss the merits of gel batteries compared to normal lead acid batteries, and compared to AGM leisure batteries.

What is a gel battery

Introducing ‘What Is A Gel Battery?’

Gel batteries are a type of lead-acid battery.

What does that mean?

Lead-acid batteries

The majority of batteries used to power vehicles, motorhomes, boats etc. are lead-acid batteries.

They’re so called because they have lead plates and an acid solution inside them. They can store charge and deliver power because of the chemical reaction between the lead and the acid.

‘Traditional’ or ‘normal’ lead-acid batteries

Traditional lead-acid batteries, the kind that have been used for many years and are still the most common type today, have the following characteristics:

Inside the battery casing they have lead plates surrounded by a free-flowing liquid electrolyte (made from sulphuric acid and distilled water).

The liquid electrolyte moves freely around the casing, and it’s the contact between the electrolyte and the lead plates during the charging or discharging process that allows the chemical reactions for charging/discharging to take place.

Gel batteries

Like all lead-acid batteries, gel batteries have lead plates, with an electrolyte (solution of distilled water and sulphuric acid) in contact with the lead plates.

The difference is that the electrolyte is not in free-flowing, liquid form.

Rather, the electrolyte is made with silica ie. sand. And so the electrolyte becomes a thick jelly-like substance, which is relatively stationary, not free-flowing. In other words, like a gel. Hence the name gel battery!

Gel leisure batteries are one of the most fitting for the leisure purpose, since they’re truly deep cycle.

Advantages of Gel batteries

  • Safer

If a traditional Flooded lead acid battery has its casing damaged, any leaking of the battery acid is highly dangerous.

Gel batteries don’t leak, since they don’t have liquid electrolyte. So they’re much safer.

  • More vibration resistant

Normal Flooded batteries don’t cope well with the vibration that occurs extensively in any vehicle.

Gel batteries, however, are much better equipped to absorb these vibrations and impacts. That’s one more reason why Gel batteries last much longer (how long do leisure batteries last?).

  • Cope better with high discharge

Regular Flooded batteries suffer and become damaged if you let them discharge too much. Doing that too often is playing fast and loose with your battery lifespan. Their natural characteristics are suited for relatively light and regular discharge/charge cycles. Discharging too much inhibits the battery’s ability to store charge and deliver power.

Gel batteries, on the other hand, are made for deep cycling. They’ll cope far better with deep discharge, and still recharge fully.

  • Can be installed in any position

Install a gel battery anywhere, on any side.

Unlike a Flooded battery, there isn’t any free-flowing battery acid that can leak out.

  • No fumes

With the electrolyte being a gel-like substance, no fumes are produced to speak of.

So there’s little need for ventilation, and this further enhances the ability of gel batteries to be used pretty much anywhere.

Why were gel batteries developed?

Gel batteries were developed to solve some of the major weaknesses of traditional Flooded batteries.

Traditional Flooded batteries were too susceptible to acid stratification. This occurs when the sulphuric acid and distilled water, which make up the electrolyte, are not well mixed. The chemical reactions that allow energy to be stored and then delivered by the battery can only occur between lead plates and well-mixed electrolyte. So when the electrolyte is not well mixed, the battery is degraded and will become ever more so until it stops working completely.

Gel batteries are completely resistant to this problem. That’s because the electrolyte, mixed with the silica, is not in liquid form. It’s in the form of a gel, and so cannot become poorly mixed.

Normal Flooded batteries were also too easily damaged over time by the vibrations of the engine.

Gel batteries internal design, mechanisms, and the electrolyte in gel all combine to make it more resistant to vibration.

Finally, regular Flooded batteries are highly susceptible to sulfation, which is the number 1 cause of battery death. Sulfation is the build up of lead sulfate on the battery plates.

It’s caused by the battery being overly discharged, being left in a discharged state too long, and not being fully charged when it is charged. These all cause more lead sulfate crystals to develop.

Since gel batteries cope better with high discharge, they are less prone to sulfation, though not completely resistant.

How To Charge Gel Batteries?

Well, luckily, we’ve got a whole article specifically on gel battery charging.

Gel vs AGM batteries

Gel and AGM batteries were both developed to solve the aforementioned problems with traditional Flooded batteries (though there are still some good ones, like this Superbatt leisure battery).

And both do so, to varying degrees.

Both come under the category of VRLA batteries (Valve Regulated Lead Acid).

As we know, Gel batteries solve the problem by adding silica, or sand, to the electrolyte, rendering it relatively immobile. AGM batteries solve the problem by absorbing the electrolyte in fibre glass mats. AGM stands for Absorbed Glass Mat. Hence making the electrolyte impossible to become poorly mixed, in a different way way than Gel battery’s solution. And also allowing for more space for lead plates. Which allows the production of more chemical reactions, and therefore more power. Their internal makeup also is more vibration resistant.

Lithium leisure batteries are even better for solving these problems, in fact they’re better in every way (and price has finally come down). Check out the best lithium leisure batteries for the reasons why.

Summing Up What Is A Gel Battery

We looked at the main properties of these batteries, to answer the question ‘What Is A Gel Battery?’.

Its primary characteristic and key differentiation with regular Flooded batteries is that its electrolyte is in Gel form. That’s because the electrolyte has been added to silica, also known as sand. The result is that the electrolyte is no longer a free-flowing liquid, which has several major advantages…

These advantages we also discussed. Increased safety, better ability to cope with discharge, no fumes, and better ability to cope with vibration. These factors, and more are why Gel batteries are so much better suited for deep cycle application, as well as being much longer lasting than a typical lead-acid (Flooded) battery.

Finally, we compared them with AGM batteries, which were developed for similar reasons and have some similar properties and advantages.