Several previous posts have said what I am going to say, but I havenít seen any that indicate they are as happy with Optima batteries as I am nor any that indicate the poster owns as many Optima batteries as I do. I own eight Optima batteries. All of them are deep cycle, yellow top or blue top.
None of my Optima batteries are recent purchases. The newest ones (blue tops) were bought in November 2001. The oldest (yellow tops) are from 1997. All of them are still in service. I have no experience with new Optima batteries, so itís possible that the quality has declined and the newer ones donít hold up the way mine have.
IF you are buying the deep cycle batteries (with a LIGHT GRAY case) the only difference between the yellow top and blue top batteries is the terminal configuration. Both have standard automotive post terminals. The blue tops have threaded studs and no side terminals, while the yellow tops have side terminals and no threaded studs. My blue tops came with stainless steel nuts and washers for those terminals.
Optima batteries with a DARK GRAY case are NOT deep cycle batteries. Some blue tops are not deep cycle and have a dark gray case. I think the model numbers that start with "D" are deep cycle, but I donít know that for a fact.
Hereís a link to a good video on the subject. This information is from Optima.
I always try to avoid discharging my batteries more than necessary, and when I do I charge them as soon as I can. I have, however, had a couple of occasions when I ran a pair of them down to about 10% charge or less. They would no longer light the gas furnace on my RV. When I got home, I charged those batteries with a charger, and they are still working.
I donít really know whether it makes a difference or not, but I use the desulphation mode on my charger periodically on all my batteries. Iím sure that my use of a real, three stage battery charger does help battery life. I donít depend on my RVís converter/charger to keep my batteries in good shape.
So far, I have gotten ten years and more from each of my Optima batteries, although the earliest ones are now starting to show their age. I will probably have to replace them in a year or so.
There are lots of folks here who dislike Optima batteries, and they probably have the experiences to back up that opinion. My experience is that they are excellent, long lasting batteries when treated well.