Gel cell batteries
are temperature regulated and voltage sensitive. So what does that mean? Gel cels are very sensitive to overcharging which causes them to over heat, at which point they can outgas, which they normally never do. This degrades the battery, seriously shortening it's life. So the voltage at which they charge has to be carefully regulated within a specific range set by the manufacturer. However this varies slightly by brand. Your charger
has a setting for two different brands. You can look up the specs on their web sites.
Exide is a well known brand name but I am not familair with Gel USA. Most of the batteries
on the market are made by a handful of companies and third party labeled. Such famous brands as Sears Diehard are actually made by some one else and branded for Sears. Often you can buy the same battery under various brand names. Many are made by Johnson Controls. Many Gel cel batteries are made by Optima and sold under several dozen brand names.
Here is web site that lists brand names and who makes them. Car and Deep Cycle Battery FAQ, Battery Manufacturers and Brand Names List, and