The Differences between AGM and GEL batteries

So what makes these batteries different?
Even though inside all AGM, GEL and flooded batteries contain lead acid, the internal construction of the battery divides them into their respective categories.

Absorbed Glass Mat or "AGM" batteries are the latest and greatest in lead-acid batteries.

An AGM battery uses a separator consisting of fiberglass between the plate and wrappers to hold the electrolyte in its place with capillary action.

Combining the lead plates, electrolyte, and fiber glass separation fibers in a confined space, AGM batteries create a "physical bond" by way of capillary action. Similar to how water creeps up a towel when it is put in a bathtub.This capillary action holds the liquid inside the glass matting, making the AGM Battery "spill proof" if it is ever exposed. Due to the tight packing of an AGM battery, it is also the most impact resistant, and boasts the least internal resistance.

The lower internal resistance increases the output voltage, decreases charging time, and reduces losses to heat as power flows through the system. AGM Batteries then bring the trump card to the table, they are maintenance free. Premium AGM batteries recombine the gases produced internally, back into liquid. This recombination makes the AGM battery maintenance free. No acid leaks, no mess while charging, no corrosion on surrounding parts. You plug in these batteries and walk away. AGM batteries can do anything that flooded and GEL batteries can do, just better. 

GEL cell batteries are also sealed just like the AGM battery listed above.

That is where the similarities end. A GEL battery uses a silica (sand) to turn the sulfuric acid into a jelly like substance.

This jelly is then used as the electrolyte. Great care must be taken with GEL batteries not to expose them to high amperage situations. High amperage situations can literally 'SCAR' the jelly inside of a GEL battery, creating a pocket. These pockets allow the plates to begin corroding, leading to premature failure. GEL batteries should not be used for fast charging/discharging, or high amperage charging/discharging situations. Use the other types listed above for these high amperage situations.

GEL Batteries are slightly stronger in regards to internal construction than a flooded battery, but pale in comparison to the physical strength of an AGM battery.