Optima Batteries
Optima Batteries are a spiral wound cell which uses absorbed glass mat design. They are well known for having different coloured tops (Red, Blue and Yellow). Many people believe these colours help differentiate what they are used for. And they aren't completely wrong. Johnson Controls that manufactures the product has always targeted its marketing of the Red Top Battery for Automotive Starting applications. And if we use the Size/Group number 34 as an example it comes with 3 different terminal options which are. 34 with the positive on the left, 34R with the positive on the right and 34/78 which along with the top terminals of the 34 has a terminal on the side for use in many American vehicles.
There are however many differences when you consider your options in the Blue and Yellow Top. Firstly the coloured tops only differentiate the different terminal layouts. If you were to look closely you'd notice that the Blue Tops have 2 sets of terminals. The first your standard SAE terminals and the second are referred to as Studs (essentially bolt like threads that stick up for you to put eyelets over with nuts to hold them in place. Yellow Tops have Automotive terminals that are much closer to the centre line of the battery so you can rotate the battery 1800 to change the positive from the left to the right side without too many issues. The Red Tops are your traditional SAE automotive terminals closely placed in the corners of the battery with the options for side and or top terminals.
What isn't covered or widely known are the options for deep cycle or cranking options within the Blue and Yellow Top models. But you might have noticed the large light grey colour of the cylinders/cells of the battery and that others are dark grey/graphite/black. This is where Optima distinguish between light grey being a deep cycle battery and black being a cranking battery.
So if you take that into account a light grey bottomed deep cycle blue top battery has exactly the same CCA and Ah as a light grey bottomed deep cycle yellow top battery, the only difference being the terminal layout. The same applies to a Red Top cranking battery with black bottom and a Blue Top battery with the black bottom which is commonly considered to be for marine but really it's just about terminal layout.