Gel System

High Current Behaviour: Good to Medium Due to the use of a thick separator, the distance between the plates is very relatively high so that the high current behaviour is limited.
The Silicon dioxide (SiO2) which forms the gel is increasing the electrolyte resistance and also limits the high current behaviour.

AGM System

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 volts are lower.

Charging Voltage: Relatively High
Due to the need for higher acid densities, the charging voltages are high.

Residual Current: Low
Due to the low charging voltages, the residual current is low.

Residual Current: High
Due to the higher charging voltages, the residual current is high.

Electrolyte Volume: High
Due to the immobilisation 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 immobilisation 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 case the 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.

Recombination: 85-95%
The recombination rate in the first year is lower than after one year

Recombination: adjustable
Can be adjusted by the volume of the electrolyte.

Overcharge Resitivity: Good
Due to the high electrolyte volume it is possible to have limited overcharge.

Overcharge resistivity: Medium
Can be adjusted by the volume of electrolyte

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 immobilisation of the electrolyte in the gel makes acid stratification impossible.

Acid Stratification Yes
The influence of acid stratification can be minimised for high cells in horizontal assembly of the cells.

Service Life: High
Due to the low acid densities the service lifetimes are high.

Service Life: Medium
Due to the high acid densities the service lifetimes are lower.