What is the difference between gel batteries and ordinary lead-acid batteries?

gel battery for solar street lights

Lead acid batteries have been around for a very long time and are still in use today. However, over the years there have been some major advancements in battery technology, including the development of gel batteries. So, what is the difference between gel batteries and ordinary lead-acid batteries? Let’s take a look.

What is a Gel battery?

The Gel battery is an improvement of the common lead-acid battery with a liquid electrolyte, replacing the sulfuric acid electrolyte with a gel electrolyte, which has improved the safety, storage capacity, discharge performance, and service life compared to the common battery.

Gel battery adopts gel electrolyte, there is no free liquid inside, and the electrolyte has high capacity, high thermal capacity, and strong thermal dissipation ability in the same volume, which can avoid the thermal runaway phenomenon of general battery; the electrolyte concentration is low, and the corrosion effect on the pole plate is weak; the concentration is uniform, and there is no electrolyte stratification phenomenon.

gel battery 1
gel battery 1

Working Principle of gel battery

The performance of the Gel battery is better than that of the valve-regulated sealed lead-acid battery. The gel battery has the advantages of stable performance, high reliability, long service life, strong adaptability to ambient temperature (high and low temperature), ability to withstand long time discharge, cyclic discharge, deep discharge, and high current discharge, overcharge and over discharge self-protection, etc.

       The domestic gel battery used for the electric bicycles is filled with silica gel and sulfuric acid solution between the positive and negative plates of the battery through vacuum filling in the AGM partition. The gel battery cannot be oxygen circulated at the beginning of use, because the colloid surrounds both positive and negative plates, and the oxygen generated on the positive plate cannot diffuse to the negative plate, so it cannot be reduced with the active material lead on the negative plate, and can only be discharged by the exhaust valve, which is consistent with the liquid-rich battery.

       After the gel battery is used for a period of time, the colloid starts to dry and shrink, generating cracks, through which oxygen goes directly to the negative plate for oxygen circulation. The venting valve is no longer frequently opened, and the colloidal lead-acid battery is close to sealed work, with little water loss. Therefore, the main failure of electric bicycle batteries is the water loss mechanism, using a gel battery can get very good results. The colloidal electrolyte is made by adding a gel agent to the electrolyte to solidify the sulfuric acid electrolyte into a gel-like substance, usually, the colloidal electrolyte is also added with a colloidal stabilizer and capacitor, and some colloidal formulations are also added with delayed colloidal solidification and retarder to facilitate colloidal refilling.

Characteristics of gel battery:

1、Fumed silica formulates high-quality colloids, the electrolyte is evenly distributed, and there is no acid stratification phenomenon.

2、The electrolyte is in gel fixed state, with no flow, and no leakage, making the reaction of all parts of the pole plate even.

3、Adopt tight assembly technology, with excellent high rate discharge performance.

4、Excess electrolyte, large thermal capacity of the battery, strong thermal dissipation ability, wide working temperature range.

5、All adopt high purity raw materials, and the battery self-discharge is extremely small.

6、Adopting gas recombination technology, the battery has extremely high sealing reaction efficiency, no acid mist precipitation, safe and environmental protection, no pollution.

7、Adopt a special design and highly reliable sealing technology to ensure the battery is sealed, safe, and reliable.

Application of gel battery:

1、Communication system: switchboard, microwave station, mobile base station, data center, radio, and broadcasting station.

2、Power plants and power transmission systems.

3、Solar street lights and wind power generation systems

4、Signal system and emergency lighting system

5、EPS and UPS systems

solar street light with gel batteries
solar street light with gel batteries

What is a Lead-acid battery?

     A lead-acid battery is referred to as a battery whose electrodes are mainly made of lead and its oxides, and whose electrolyte is a sulfuric acid solution. In the discharged state, the main component of the positive electrode is lead dioxide and the main component of the negative electrode is lead; in the charged state, the main component of both positive and negative electrode is lead sulfate. It is divided into exhaust-type batteries and maintenance-free lead-acid batteries.

lead acid battery
lead acid battery

Characteristics of lead acid battery:

1、Safe and sealed

In normal operation, the electrolyte will not leak out from the terminals or the shell of the battery.

2、No free acid

The special liquid-absorbing partition keeps the acid inside, and there is no free acid inside the battery, so the battery can be placed in any position.

3、Drainage system

When the internal pressure of the battery exceeds the normal level, the VRLA (Valve-Regulated LeadAcidBattery) battery will release excess gas and re-seal automatically to ensure that there is no excess gas inside the battery.

4、Simple maintenance

Due to the unique gas compound system, the gas produced is converted into water, so there is no need to add water while using the battery.

5、Long lifetime

Adopted lead-calcium alloy bar plate with an anti-corrosion structure, the battery can be used for 10-15 years by floating charge.

6、Stable quality and high reliability

Adopting an advanced production process and strict quality control system, the quality of the battery is stable and the performance is reliable. Voltage, capacity, and sealing are 100% inspected online.

solar street lights with gel battery
solar street lights with lead acid battery

Application of lead acid battery::

Backup power supply

1、Telecommunication

2、Solar energy system

3、Electronic switch system

4、Communication equipment: base station, PBX, CATV, WLL, ONU, STB, cordless phone, etc.

5、Backup power supply: UPS, ECR, computer backup system, sequence, etc

6、Emergency equipment: emergency lights, flashlights, fire and theft alarms, fire gates

Main power supply

1、Communication equipment: transceiver

2、Electricity control locomotives: collection vehicles, automatic transport vehicles, electric wheelchairs, cleaning robots, electric vehicles, etc.

3、Machine tool starter: lawn mowers, hedge trimmers, cordless drills, electric drivers, electric sleds, etc.

4、Industrial equipment/instruments

5, camera: flash, VTR/VCR, movie lights, etc.

What are the differences between gel batteries and ordinary lead-acid batteries? 

There are three main aspects.

1. The lifespan is different.

Conventional lead-acid batteries are generally: 6-8 years

Gel battery is generally: 12 years.

2. The use environment is different.

Ordinary lead-acid batteries generally can not exceed minus 3 ℃.

The gel battery can work at -30℃.

3. Safety.

Ordinary lead-acid batteries have the phenomenon of crawling acid and will explode if not properly managed.

Gel batteries do not have the phenomenon of acid crawling and will not cause explosions.  

The specific differences between the two are as follows.

 Gel BatteryOrdinary Lead-acid Battery
Design life (@20°C)12 years6 to 8 years
Electrolyte adsorption technologyColloidal adsorption technologyGlass wool adsorption technology
Advantage 1The interior is a gel electrolyte with no free electrolyte phenomenon.The acid is absorbed in the glass dimensional blanket sheet and a large amount of free electrolyte is present. Leakage is likely under strong charging conditions.
Advantage 2The electrolyte has about 20% capacity, so it remains extremely reliable during high-temperature operation or overcharging, and the battery does not “dry out”. The battery has a wide range of high and low temperatures.The amount of electrolyte is less than the required 20% (acid-poor state), so the reliability is low during high-temperature operation or overcharging, and the battery is bound to “dry out”.
Advantage 3The concentration of the colloidal electrolyte is the same above and below, and no acid stratification occurs. Therefore, the reaction is uniform, and the pole plate will not change shape and cause an internal short circuit under high rate discharge.The liquid electrolyte has a difference in concentration between the top and bottom due to deposition (acid stratification phenomenon and acid stratification is irreversible). Therefore, the reaction is not uniform, which leads to deformation of the electrode plate at a high discharge rate, and even breakdown of the plate pole, resulting in an internal short circuit.
Advantage 4The positive electrode plate is a high-quality antimony-free alloy, with a very low self-discharge rate. The self-discharge rate of the battery is less than 0.05% per day at a room temperature of 20℃, and the original capacity of 50% is still maintained after two years of storage.The average lead-calcium alloy pole plate has a high self-discharge rate. Under the same conditions, it must be recharged after about 6 months of storage. Longer storage time will expose the battery to the possibility of damage.
Advantage 5There is an internal deep discharge protection mechanism so that the battery can still be connected to the load after deep discharge. Charging within four weeks does not impair the battery’s performance. The nominal capacity of the battery is quickly restored after recharging, and the battery life is not affected.Deep discharge must cause permanent damage to the battery, once discharged, if it can not be recharged within a short time to recover, the battery is immediately scrapped. That is, the full length of the battery can be restored after charging part of the capacity, and the battery life and reliability will be greatly reduced.
Advantage 6The specific gravity of the acid is low (1.24), and the corrosion of the plates themselves is relatively lowThe high specific gravity of the acid (1.33), and relatively high corrosion of the plates themselves

Conclusion 

       Gel batteries and ordinary lead-acid batteries are the same in performance, except that the electrolyte inside the battery is a semi-solid state of latex and a liquid state, and the ordinary lead-acid battery in the liquid state needs to be maintained by adding distilled water from time to time during use, while the colloidal one does not need to be maintained by adding distilled water (usually called maintenance-free).

      The disadvantage of a Gel battery is that overload charging and discharging is very harmful, once overload charging and discharging will cause an unrecoverable battery, even scrap. In contrast, ordinary lead-acid batteries need to be overloaded resulting in pole plate deformation and sulfation can be restored by small current charging and discharging (just can not restore the original state); personally, I feel that the colloidal is clean and safe, and ordinary lead-acid batteries are better adaptable (adjustable in winter and summer). However, whether you choose a gel battery or an ordinary lead acid battery, you need to buy from an honest manufacturer, the other article would help you choose the right suppliers  “Uncover the market chaos of solar street light battery”.

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