Categories: Autonomous power supply, How does it work
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Gel batteries and their use

 

Lead-acid batteries are widely used both as traction batteries (for example, to power electric forklifts) and as starter batteries for cars. Uninterruptible and backup power systems for homes and enterprises also use lead-acid batteries.

Autonomous power supply systems of houses often contain a high-capacity battery, or an assembly of several hundred ampere hours, designed to provide long-term power supply to the home.

Gel batteries and their use

Such a battery can be charged from various alternative sources of electricity, such as a solar panel unit, a wind generator and others, and the battery is discharged traditionally through powerful inverter, from which consumers are supplied with alternating current of industrial frequency and standard mains voltage.

Ups

Conventional uninterruptible power supplies for computers also include a sealed ampere-hour lead-acid battery.

Battery

The first lead-acid batteries used exclusively an aqueous solution of sulfuric acid, prepared with distilled water, as the electrolyte, so that calcium and magnesium salts, usually present in water, would not interfere with the battery operation. Such a battery was made as follows.

Lead gratings are immersed in the electrolyte, into which lead dioxide (on the anode, positive electrode) and metallic lead (on the cathode, negative electrode) are pressed in powder form.

A porous separator made of polyvinyl chloride powder (Miplast), microporous ebonite (vulcanized mixture of rubber with silica gel and sulfur - Mipor), or polyethylene, the function of which is to prevent the electrodes from closing together, is placed between the plates.

If you connect six such cells in a serial circuit, you get a 12 volt battery, respectively, a larger number of cells will give a higher voltage.


Starter batteries with liquid electrolyte are used everywhere in automobiles, but the peculiarity of these batteries is that when a large current flows for a long time, their liquid electrolyte can easily boil. That is why in such batteries the ability to add electrolyte is provided.

Their porous plates of a large area allow you to briefly receive a current of 200-300 amperes to power the starter. However, for long-term operation in alternative power supply systems and uninterruptible power supplies, such batteries are of little use.

AGM (Absorbent Glass Mat)

In the early 1970s, engineers at the American company Gates Rubber Company developed a new type of sealed lead-acid battery based on absorbed electrolyte.

The technology is called AGM (Absorbent Glass Mat). For the first time, fiberglass impregnated with electrolyte was used as a filler in the battery compartments. Later, the electrolyte began to thicken by adding silica gel (a mixture based on solutions of silicic acids), this created additional pores in which the electrolyte was now better retained and allowed to completely fill the space between the plates. A new type of battery has gained wide popularity as a “gel battery” because the aggregate had a gel consistency.

Gel batteries

This solution allowed us to obtain a number of important advantages over batteries with liquid electrolyte. Firstly, there is no need to maintain a new type of battery, because gas is not released outside, it is absorbed in the pores, and boils nothing, the electrolyte does not change its density either during charging or during discharge. The plates no longer crumble.

Gel battery

The gel battery can work in absolutely any position, even upside down, nothing will pour out and not be broken. Valve control prevents acid leakage and eliminates terminal corrosion. The performance of the gel battery does not fail even at temperatures up to minus 30 degrees Celsius.

A service life of up to 10 years, as well as resistance to deep discharge - these are the qualities that make a gel battery a promising tool for efficient power supply based on alternative energy devices.

The design features make the gel-based battery less susceptible to sulfation than a regular AGM battery, and therefore gel batteries can remain in a fully discharged state for several days without affecting the capacity. A gel battery is capable of withstanding an average of 50% more discharge cycles than a regular AGM battery.

One well-known manufacturer of such batteries claims that their gel batteries can carry 350 discharge cycles with a depth of 100%, up to 550 with a depth of 50% and up to 1200 with a depth of 30%. These are excellent results that keep operating costs to a minimum, whether it concerns an autonomous power supply system or uninterruptible power supply.

Battery device
Battery device
Battery device

More and more, in some Western countries, gel batteries with spiral plates are gaining popularity, which can be much larger in area than in compact cases.

Gel battery with spiral plates

Due to the large area of ​​interaction of the plates, the currents in such batteries can be extremely high. In some batteries, this figure reaches 800 A and even higher. The only serious drawback of all modern gel batteries is the high price.

Useful moments for working with batteries:

Battery capacity measurement

Parallel and serial connection of batteries

See also at i.electricianexp.com:

  • Lead-acid battery - device and principle of operation, varieties
  • Popular Battery Types
  • Batteries MNB Battery
  • The device and the principle of battery operation
  • Lithium polymer batteries

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    Comments:

    # 1 wrote: Andrew | [quote]

     
     

    The whole problem with gel batteries is that they need a special charger (power supply, it's an adapter). Without it, it makes no sense to charge with 10 percent current. After a year of charging in a convenient way, the gel battery is killed off. And there are no specialized circuits (such as KREN 142) for charging gel batteries.