Mazda MIATA MX-5 L4 1.6L 1990-2005 Battery Replaces SLIU1RT

*This is an updated review*This battery is likely one of the most reasonably priced AGM batteries on the market (and not just for a Miata). It is compact, powerful and relatively lightweight for its output. It is also an excellent replacement for Group 51 batteries (used in several Honda models).There was a concern with first battery that was shipped due to inadequate packaging - but that problem was quickly resolved and handled with outstanding customer service. I will get to the packaging later in the review.The battery arrived charged to 12.83V - which is more than sufficient to enter into starting duties. Nevertheless, I hooked it up to my Solar PL2208 Pro-Logix charger (please see my review) and ran it through a charging cycle to determine if it was actually "fully charged". The Pro-Logix line of chargers are excellent, fully computerized/automatic chargers that are optimized for the correct charging of AGM batteries (and pretty much all other types of car batteries as well) - and I highly recommend them. The battery took approximately 35 minutes to fully charge using the PL2208 charger, which demonstrates the battery was in fact close to being fully charged. The PL2208 can take up to 10 minutes to go through its multi-phase charging cycle (to include battery diagnostic) when a battery is essentially full. The PL2208 also automatically defaults to a true trickle-charge mode once the charging cycle is complete.As noted above, I am using this battery in place of a Group 51 battery (in an older Civic) and it fits into the OEM battery location without a problem. The battery fits perfectly into the narrow battery tray (essentially the same width as a Group 51 battery), but it is 2 inches shorter in both length and height when compared to a Group 51 battery. This necessitated using shorter battery tie-down posts and I chose to use a small spacer block to fill the rest of the battery tray (water-proofed piece of a 2X4 screwed into the tray), but I don't think the spacer is necessarily required. The smaller dimensions result in an overall lower center of gravity as well as saving 1.2 lbs overall - while sacrificing nothing in performance. The battery appears significantly more compact than the Group 51 it replaced - but matches the 51 in pretty much every specification that counts. The overall cost of this compact AGM battery (including shipping) was also about $7 less than purchasing the cheapest replacement Group 51 wet-cell battery from any local retail store (including Walmart, Sams Club, Auto Zone, NAPA, Pep Boys and O'Reiley's). Moreover, if I am given the choice between a wet cell and an AGM battery I would choose an AGM battery every time - even at a price premium. In this case it was slightly cheaper - so you really can't beat that.On a side note: I currently have an Odyssey battery (PC925MJT) in my Honda S2000, which is similar in size and weight to this battery. The OEM battery for the S2000 is also a Group 51 battery. I will strongly consider replacing the Odyssey battery (once it dies) with one of these batteries. While the Odyssey battery has an advantage in absolute output over this battery, the Odyssey's price is over twice as much (including shipping). Nevertheless, the cost difference alone will make the experiment worth the try. Hopefully that will be a much later post (The Odyssey had better have a few more good years left in it for as much as they cost).I will cover shipping/packaging and customer service in this part of the review.As mentioned before - I had a problem with the way the first battery was shipped. The first battery arrived in a damaged box that was not robust enough to contain a 25lb battery. In fact, the packaging was nearly identical to the failed packaging described in "YSC's" excellent review from 2010 (double-boxed with shipping peanuts between the outer and inner boxes). Surprisingly though, the battery showed no significant outward signs of being damaged and it was holding a good charge. Nevertheless, I contacted Battery Mart because I was concerned with the longevity of the battery due to the way it was packaged (and the condition of the outer box) - and I wanted the company to know they needed to review and improve their shipping processes. I have to give a lot of credit to Battery Mart for being EXTREMELY responsive in resolving my concerns. In fact - the owner personally reviewed and revamped their shipping QA processes. The owner also had another battery immediately shipped out to replace the first battery. This was done on his own initiative - and was not requested by me. The replacement battery arrived 4 days after I received the first battery. The shipping box and packaging were a substantial improvement over the first shipment - and the battery suffered no shipping damage at all. The battery was shipped in a strong tri-wall shipping box and the battery was protected and restrained with robust plastic/foam packaging and card board buffers. I dealt with the manager on the phone and he was extremely courteous and helpful. The manager stated they have rarely had complaints about packaging - and they take every complaint very seriously. The manager assured me the review of their packaging quality control procedures was thorough and they made several changes to help prevent any future packaging issues.

My previous Marathon 8AM-U1R Miata battery lasted > 10 years! This is a fantastic AGM battery for NA Miatas (mine is a 1991). In my experience, they are as good as the (superb) original Panasonic, and much better than the old Westco.Here is my 1991 Miata's "battery history" (going mostly by memory, but I'm quite sure I'm pretty close):1991 - 2002: The original Panasonic AGM battery lasted 11 years!2002 - 2003 (?): A WestCo AGM battery marketed for Miatas. Lasted much less than a year (but see notes below).2003 - early 2014: This Marathon 8AM-U1R lasted over 10 years and was still working when I replaced it (with the same model) in February 2014, mostly just for peace of mind!Notes:I admit I may have mistreated the WestCo by letting it sit "too long" unused (like, two to four months, maybe?), but I'm sure I DID charge it fully when I received it. During this time it was in a fairly well temperature-controlled garage, too. I also admit my memory is vague on this. But it certainly didn't last more than a few months.Also, the old Marathon battery had some unusual treatment that may _possibly_ have extended its life -- however, I believe this treatment would have in fact _shortened_ its life. OK, I'm ashamed to say that my 1991 Miata sat unused in the driveway for five, or maybe six, years, with my "old" Marathon battery in it. This would have been about 2007 to early 2013. During this time, I believe I charged the battery just a few times. I was certainly not conscientious about it. Amazingly, after a trickle charge, this battery easily started the Miata and worked fine for several months! I decided to replace it (with the same Marathon battery) because I just couldn't believe it was still working and I wanted peace of mind!(As a testament to the original Miata's reliable design, with a full tank of 5 or 6 year old gasoline and all those years of neglect, it started right up and took only a change of fluids and a new soft top to renew the love affair I've had with this car!)I am a believer in the AGM automotive battery technology, and highly recommend this Marathon 8AM-U1R battery. Just for fun, you can see my uploaded photos of this new battery (installed in the trunk), and my old 8AM-U1R (in the garage).