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?? What is the difference between sealed Gel and sealed AGM batteries ??

 

Gel Batteries *Sealed valve regulated lead acid batteries (VRLA), with gel electrolyte. Highest reliability guaranteed, even for cyclic applications.

Absorbed glass matt (AGM) batteries *Sealed valve regulated lead acid batteries (VRLA), with starved electrolyte. Extremely good high current discharge, economical.

 

System Comparison

VRLA Gel Batteries to VRLA Absorbed Glass Mat (AGM) Batteries

Both technologies are sealed and maintenance-free but...

 

Gel System

AGM System

High Current Behaviour: Good to Medium

Due to the use of a thick separator, the distance between the plates is relatively high so that the high current behaviour is more limited.

The Silicon dioxide (SiO2) which forms the gel is increasing the electrolyte resistance and therefore limits the high current behaviour but also decreases the self-discharge rate.

High Current Behaviour: Good to Very Good

Based on the glass mat construction - the distances between the plates are small - so AGM batteries have a discharge rate of approx. 30 minutes or less, which is up to 5% more capacity than gel batteries.

Charging Voltage: Relatively Low

Due to the use of low acid densities, the charging voltages are sometimes lower.

Charging Voltage: Relatively High

Due to the need for higher acid densities, the charging voltages are high.

Acid density:  Low

Due to the use of low acid densities, corrosion-attack on the plates is much lower. resulting in improved lifetime.

Acid density:  High

Density is higher, often resulting in a better volume/power relation.

Electrolyte Volume: High

Due to the immobilization of the electrolyte in a gel and the filling of free cell volume with gel, the electrolyte volume is high.

Electrolyte Volume: Low

Due to the immobilization of the electrolyte in a glass mat only, the space between cells is filled with electrolyte.

Thermal Capacity: High

Due to the high electrolyte volume the thermal capacity is high.

Thermal Capacity: Low

Due to the low electrolyte volume the thermal capacity is low.

Thermal Exchange: Good

The generated heat can easily flow to the case walls because the whole volume of the cell is filled with gel.

 

Thermal Exchange: Medium

The generated heat cannot easily flow to the case walls because the cell is not completely filled with electrolyte. The heat can only flow easily to the walls where the plates are within contact with the walls.

Cyclic behaviour: superior

Perfect cyclic behaviour and very good resistant against repeatedly deep discharges.

Proof against deep-discharges acc. to       DIN 43534 T.5

 

Cyclic behaviour : low to medium

Deep discharge of the battery enormously reduces the battery's lifetime.

 

Overcharge Resistance: Good

Due to the high electrolyte volume it is possible to have limited overcharge.

Overcharge Resistance: Medium

Due to the low volume of electrolyte overcharge has to be avoided.

Thermal runaway: Very rarely

The system is thermally stable because the residual current is low, the thermal capacity is high and the thermal exchange rate is good.

Thermal runaway: Often

The system is more thermally unstable because the residual current is high, the recombination is high and the thermal exchange is not good.

Acid Stratification: No

The immobilization of the electrolyte in the gel makes acid stratification impossible.

Acid Stratification: Yes

The influence of acid stratification can be minimized for high cells in horizontal assembly of the cells.

Service Life

Less sensitive to negative lifetime influences

Service Life

Lifetime heavily influenced by items like ripple, temperature, (dis)charge etc...