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Charging a gel battery with a stationary charger is a procedure that can easily kill a battery. They often die under the hood if there are problems with the on-board voltage. Therefore, before charging a gel battery, familiarize yourself with its main technical features and the algorithm of actions presented in this article. Everything said below has been tested in practice. Not in British laboratories, of course, but in an ordinary garage. But still.

Technical features of GEL batteries

Gel battery for car
Gel battery for car

Without really understanding the technology, many "experts" like to say that gel batteries are new, something prohibitively high-tech, complex, and so on. Not really. Of course, the gel-like electrolyte in power supplies began to be used much later than the liquid one. But not yesterday, and not even the day before.

According to history, the first gel batteries appeared at the dawn of the development of space technology. And this, for a second, more than half a century ago. Air conditioning with a navigator, for example, is much "younger". Although for many, this is far from new technology. In fairness, we note that specifically GEL batteries came to the automotive industry relatively recently. But only because they are fabulously expensive.

According to the device, a classic gel battery is not much different from the usual standard one. The same hermetic case. Inside are lead plates from which cells are assembled, and those are already connected to a battery. But the electrolyte here is gel. That is, it has a gel-like consistency. In addition, if some gels in nature have at least some fluidity, then in batteries it is closer to solid than to liquid.

Gel battery inside
Gel battery inside

People say that for the manufacture of GEL batteries, especially carefully purified lead is used. Actually it is not. Lead is purified in the same way in the production of any other modern batteries. Although in some cases this point is passed off as a feature of gel batteries to justify their high cost.

Let's summarize. There is nothing beyond natural in GEL technology. However, the fact that the electrolyte in them has a gel-like consistency is important for answering the question - how to charge a gel battery. Therefore, we will return to this.

Can gel batteries be charged at all?

At one time (and maybe now) there was a bike that it was impossible to charge gel batteries at all. Most likely, those who tried to charge, but did it wrong, gave rise to this myth. As a result, the battery swelled up, irretrievably lost its capacity, or stopped taking a charge altogether. This is not very difficult to achieve. Further it will become clear how.

You can charge gel batteries, and even need to. The considered myth is so stupid that there is no particular desire to write about it. But it will have to. Remember once and for all: if something is called a battery, then it can be charged. And it doesn't matter what technology it is made by. The key word here is battery - a reusable power source.

But you need to charge the GEL battery correctly. By erroneous actions, it can be disabled in just one charge cycle.

Is it worth buying a GEL battery for a car

Let's briefly consider whether it is worth giving preference to a gel battery, refusing more affordable options. To draw conclusions, we need to go over the merits of the technology, as well as our main topic - charging.

Manufacturers and sellers attribute the following advantages to GEL batteries:

  • extended service life;
  • can be tilted and flipped;
  • effective charge reception;
  • insensitivity to deep discharges;
  • low self-discharge.

All these advantages are really not invented for the sake of advertising and justifying the high cost of gel batteries. They are really capable of serving for a long time, they can be discharged to zero, and by themselves they are discharged very, very slowly. But only under one condition - if the GEL battery has been charged correctly throughout its entire service life.

Therefore, if you are not sure that you can charge a gel battery as described below, then it is better not to buy it. First, overpay for benefits you will never get. Secondly, today there is a worthy and more affordable alternative. In the end, even conventional batteries with a liquid electrolyte in a modern design can last much longer than the prescribed 5 years. Albeit with some reservations. And for a car battery, such a period is an achievement that deserves respect.

About special chargers for GEL batteries

Special chargers for GEL batteries
Special chargers for GEL batteries

They were invented for those motorists who could not or did not want to figure out how to charge a gel battery. Naturally, they cost much more than the usual good chargers. But what do they “know how”, for which we, motorists, have to overpay? And nothing, except for limiting the charge voltage at a certain point.

GEL type car battery chargers can't even do that. Because you know where they were made. The author of the article had to repair this kind of memory several times, and the disassembly clearly proved the above. The circuitry of some models does not even come close to stabilizing or limiting the charging voltage. Meanwhile, this is the most important thing for a gel battery.

So be very careful about how to choose a battery charger.

How to charge a gel battery

Let's return briefly to the technical features of gel batteries, as promised above. Namely, to the gel-like state of the electrolyte. When, during the charging of a conventional battery, the voltage exceeds the norm (14.4 V), the liquid electrolyte begins to “boil”. What happens in this case, read the article - why the battery boils.

A gel-like electrolyte cannot boil because of its state of aggregation. But it can flake off, that is, lag behind lead plates. This process is in most cases irreversible. As a result, the contact area between lead and electrolyte decreases. And at the same time, the battery capacity decreases and the maximum starting current decreases. Moreover, in this scenario, there is a high probability that the battery case will swell or even collapse.

From this all follows the main rule for charging a gel battery: in no case should the charge voltage be exceeded. The norm here, as for conventional car batteries, is 14.4 V. The maximum is -14.5 V. If you charge the battery and apply more voltage to it than indicated, this will lead to the electrolyte peeling off the lead plates.

Swollen gel battery
Swollen gel battery

For this reason, it is highly recommended that you have:

  1. A charger in which the voltage is limited electronically, or this can be done manually.
  2. The device for the control measurement of charge voltage is a multimeter.

As the first, almost any charger is suitable, which provides for classic modes or manual voltage adjustment. As a matter of fact, even home-made memory devices with such adjustments can also be used. The main thing is not to miss when the voltage begins to rise during the charging process, and exceed the specified values.

A multimeter is needed in any scenario. Even if such a device is on the charger, it is not a fact that it displays what it really is. First, built-in voltmeters are often not calibrated. Second, they measure the voltage at the output of the device's circuitry. And it is important for us to know and control the voltage that is available directly at the terminals of the gel battery. You can accurately measure it using a multimeter connected directly to the terminals.

Multimeter selection
Multimeter selection

Practice shows that it is not advisable to buy an expensive electronic multimeter for this task. Such devices, as radio amateurs say, "think for a long time." This means that they show the voltage with a slight delay. Therefore, for additional control, buy inexpensive multimeters. Although they are not as accurate, they are “fast”. And their accuracy is usually enough not to ruin the gel battery when charging. In extreme cases, you can also calibrate the multimeter.

Gel battery charging algorithm:

  1. It is advisable to disconnect the battery from the on-board network. It is not necessary to do this, since charging the battery will be a safe voltage. What is at stake, read the article on how to charge a calcium battery.
  2. Connect a control voltmeter (multimeter) to the battery terminals.
  3. Turn on and set up the charger in accordance with its instruction manual.
  4. If it is possible to select the charge current, set 10% of the actual capacity (not the one that is written on the case).
  5. If voltage regulation is provided, it must be limited to 14.4 V.
  6. Connect the charger to the gel battery terminals.
  7. Control charging current and voltage. The indicators should not be higher than indicated in paragraphs 4 and 5.
  8. When, at a voltage of 14.4 V, the charge current drops to 0.1-0.3 A, the gel battery can be considered fully charged.
  9. In the event that the charger is manually controlled, it is advisable not to miss this moment so that the recharge does not go.
  10. Automatic chargers will turn off the charge on their own. Although often they do it ahead of time.
Gel battery charging voltage
Gel battery charging voltage

How to make sure that the charging of the gel battery was successful? For obvious reasons, we cannot measure the density of the electrolyte. There is no green indicator, as in conventional batteries, since it only works in a liquid medium. All we have in this case is the tension of rest. In order to determine from it how much% the gel battery is charged, it must be correctly measured, and then compared with the data in the table below.

Resting voltage is the voltage at the terminals, which is measured after 8-12 hours of inactivity of the battery. That is, after you have charged the gel battery (or any other), let it stand idle for the specified time or longer. Then measure the voltage at the terminals. The obtained indicators will be the rest voltage. Here is the table.


Quiescent voltage (V)

Charge (%)

< 11.90























Incorrect measurement


A few words should be said about incorrect measurement. Quite often, after a standstill of 8-12 hours, the resting voltage is not reached. That is, the voltmeter shows 13 volts, and even more. Do not think that this is your battery some kind of special. No. It's just that the resting tension has not yet been reached. As a rule, if, after charging the gel battery, it immediately connects to the on-board network and simply stands “out of work”, the rest voltage is reached in 6-7 hours.

Separately from the onboard network, you have to wait a little longer. One way or another, if you charged a gel battery today, and in the morning the voltmeter showed more than 12.7 V, then there is every chance that you did everything right. The battery is charged and ready for further use. If the rest voltage is somewhere within the above plate, that is, less than 12.7 V, then the battery was not fully charged.

There are three important factors to keep in mind when measuring quiescent voltage. Firstly, if the battery is left connected to the on-board network, then in 8-12 hours it can be slightly discharged by the car's devices operating in standby mode. Secondly, there is such a thing as a large leakage current. Thirdly, self-discharge should not be written off either. For gel batteries, it is extremely low when they are new. If yours is several years old, then self-discharge can be very significant.

Do I need to charge a new gel battery

New gel battery
New gel battery

This topic is discussed in great detail in the article - do I need to charge a new battery. What was said in it applies to both conventional batteries and gel ones. If you are too lazy to read or there is no time, then here is a quick answer to the question: a new gel battery needs to be charged, but not always. It happens that “out of the package” the battery is already normally charged. The main thing is to know how to correctly determine it. This is also described in the article, the link to which is presented above.

Brief summary

Charging a gel battery is not much different from a similar procedure with classic car batteries. There is only one important rule - do not exceed the charge voltage. If this moment is missed, then the GEL battery will irrevocably deteriorate. The gel-like electrolyte will lag behind the lead plates, the capacity will decrease, the starting current may swell the case. Later, such a battery may “refuse” to accept a charge.

VIDEO: about gel battery