Miata Battery Alternatives

Early Miatas came with an excellent AGM type battery that has been known to last upwards of 10 years with proper care and feeding. As nothing lasts forever, sometimes a replacement battery is needed. I've relied on a battery from Westco for many years. It's pretty much a direct fit for the Miata and uses the same AGM technology which is better and safer for the Miata's battery location in the trunk of the car.
As much as I'd like to continue to buy Westco batteries, I have to be fiscally responsible and ensure that I'm getting the best value for my money. So, I shopped around and found the Marathon battery being sold on Amazon.com by a company called Battery Mart (just search for "miata battery" on Amazon and it will come up). It is an AGM battery and with the exception of the top cap, looks to be pretty much the same battery as the Westco. The part number - 8AMU1R - confirms it. It's the same East-Penn Deka battery as the Westco. The Marathon version was $79.95 plus $23.50 for shipping. The Westco generally sells in the $120 range, before shipping, however I did find a good deal here at $99 and $9.95 for shipping, which puts the Westco only $10 more than the Marathon.

Correct size and the posts on the correct sides for a proper fit in the Miata. This one is going in the '99.

Side-by-side with the Westco, the similarities and slight differences are obvious.

The service from Battery Mart was good. I ordered the battery on Monday and it arrived on Thursday, triple-boxed and well padded.