Batterie warenty?

I'm on the way to Costco

Some part of what you are paying for is the warranty, so if they have the same ratings and same price, I would choose the longer warranty. Not unusual for physically equivalent batteries to be sold with different warranty lengths, at different prices. Warranty is a marketing tool, with a cost, not a quality indicator.

However, if the battery with shorter warranty is 20-30% heavier, and has 20-30% higher capacity ratings, I would buy the heavier battery at the same price. Might even pay extra for it.

Except for one instance in which I took back an initially defective Sears DieHard, I've never gotten much return on automotive battery warranties. Most don't lose enough capacity to fail during the warranty period, and most of the warranties are pro-rated for service time. You want a warranty that is 100% for long enough to cover defects, which will usually show up in the first few months if you have enough discharge-charge cycles.

I'd go the Costco route.

Batteries are made by the same mfg. Everstart does offer different levels of quality but in the end, Costco is normally the better deal as they work on shorter margins so can sell for less.

I run EverStarts in my boat (4 batteries- 2 engine, 2 trolling) mostly because if one goes bad, it's usually easy to find a Wal-Mart nearby to replace one.