Translations:Fonctionnement, entretien et régénération de batteries au plomb/46/en

Gel batteries are a type of sealed battery / VRLA. In a gel battery, the electrolyte is gelled by adding silicate.
View the inside of a gel battery

Advantages Disadvantages
Maintains the homogeneity of the electrolyte perfectly Limited peak current
Low self-discharge (1-3% per month) Slow charging and discharging. (charge current limited to 5-10% of capacity)
Cannot withstand high temperatures (loss of electrolyte in the form of gas - permanent effect)
Longer life span/shelf life Sensitive to overload (loss of electrolyte in the form of gas)
High cost