2) What is the difference between a gel cell, an AGM and an SLA battery?
Both type of batteries are sealed, valve regulated batteries allowing them to be used in any position. The difference lies in the way the electrolyte is immobilized. In case of AGM (absorbed glass mat), the newer of the two technologies, the electrolyte is absorbed by the glass fiber separator who acts like a sponge. In a gel-type battery the liquid electrolyte turns into a gel right after the battery is filled. Gel batteries use a different type of separators which are not absorbent. Because of the design, gel cell batteries don't offer the same power capacity as do the same physical size AGM battery. For example, an AGM battery that is 12V 100AH, whereas, for example, a gel cell battery in the same size case would only be rated at 84AH.However, the Gel Cell excels in slow discharge rates and slightly higher operating temperatures. The internal design is otherwise similar.