Son of "Two Week" Miata Battery

On 1/21 I posted a message indicating my '03 SE battery could not start my garaged Miata after a 2-week hiatus this winter. My local dealer said that was normal considering all the things that drain the battery when not running.

I wrote to Miata USA to verify whether the dealer was accurate when indicating it was normal, as well as verify the battery's specs. Mazda replied as follows:

"Yes, it could be normal depending on one factor. I don't really know the weather conditions there, but if it's cold, this would be normal." ("Editor's" Note: I had told Mazda my garage has not gotten colder than

38F).

As for the battery's specs, "I have spoken with our Product Engineers ... . They advised the battery equipped in the Mazda Miata is a gel battery. However, it's not rated in cold crank amps. The battery is rated at 32 amp hours." ("Editor's" Question: Can a battery be accurately load-tested at a local shop when I don't know the CCA rating?)

Now for the upshot: Rather than fret any further about whether a 2-week battery is "normal," I went with a trickle charge to the battery when not in use. I bought a Battery Tender Plus (see

formatting link
Though largely intended for motorcycle and sports equipment batteries, it works for the slightly larger Miata battery. Although I don't think it could charge the battery from 3V or below, it has been doing a GREAT job so far, supplying 0.1 amps or less once in its trickle-charge mode. You can just plug it in and (almost) forget it, though it's best to do a visual check of the battery once a week.

I think of it as an IV of electrons. With its quick disconnect to the battery, I can unplug and go. As for now, there's plenty of messy slush out there, so it's waiting time until my next winter drive.

Alan '03 MiniMi, the SE

Reply to
AlanRab
Loading thread data ...

It sounds to me like Mazda is just doing the typical corporate thing and COVERING THEIR ASSES. With us sue-happy Americans, nobody seems to be willing to just be straight with you, afraid the dealer will get BLAMED, they just give you a worthless response which while it doesn't help you, it doesn't hurt the dealer.

Can you say run-on-sentence! Sorry

Chris

92BB&T
Reply to
Chris D'Agnolo

OK, what is the bottom line? Do the M2 Miatas still come with a gel cell from the factory or not? It is well established that the Mazda replacement is an ordinary wet cell, but is the original still gel?

Leon

Reply to
Leon van Dommelen

On Sun, 08 Feb 2004 00:16:05 GMT, rammm@REMOVE_THIS_TAGdommelen.net (Leon van Dommelen) wrote in news: snipped-for-privacy@4ax.com:

The 'original' M1 battery was AGM not Gel. Bit of a difference.

As far as I know the new ones come with a regular wet battery. But I haven't looked under the trunk lid at one.

And for those that track these things, the -30°C weather here was too much for my original battery a few weeks ago and inspection showed it was leaking. So I headed out to the only over-the-counter place to buy a true and proper AGM replacement here in Ottawa where I paid about C$120 including all taxes. If I have to replace it every 13 years I won't be too upset. It was a bit taller and narrower than the original, but all the bits and pieces were in the right places so it was a ten minute swap job.

The neat thing was that they had a cutaway model to show how the AGM battery was different from the wet cells.

Reply to
Dave Null Sr.

Reply to
AlanRab

i just replaced the OEM battery in my '99 sport (a very early M2). definitlely an AGM.

dookie

Reply to
dookie

Sorry, I don't buy it. My Miata sits in a garage, where it has gotten as low as -20, and for longer than that, with an OEM battery, and started without a whimper. It's an 01, BTW.

Tom Crystal Blue

Reply to
altar

True. I misspoke.

Leon

Reply to
Leon van Dommelen

What I don't get is *why* the replacement is a wet cell, when the original Panasonic is still on sale:

formatting link

Reply to
Per K. Nielsen

Wonder what the 'G' in 'AGM' means?

Yes, I know that what is usually referred to as a Gel battery and an AGM is not the same, but to say that an AGM is not a Gel is untrue.

Reply to
Per K. Nielsen

Hi Per,

What is an AGM battery?

AGM is an abbreviation for absorbed glass mat battery. In this battery design, the acid is completely absorbed into glass mat separators which are sandwiched between the lead plates. It's a totally sealed and maintenance free design. There are no discharge tubes or fillers caps, which eliminates the need to maintain water levels and offers no concern about acid leaks on valuable parts and accessories.

AGM batteries offers several advantages over conventional "wet" batteries:

- Sealed maintenance free battery design means you never have to worry about checking water levels.

- AGM battery technology will not leak or corrode on paint and chrome.

- They have less internal resistance which offers more CCA amperage than wet batteries.

- By nature AGM batteries are more heat and vibration resistant than conventional batteries, both which contribute to the large majority of failures in motorcycle applications.

- Slower self discharge rate (longer shelf life) means battery can sit for extended periods of time without constant monitoring. A wet battery discharges 15% a month, where AGM batteries discharge only 2-3% a month.

- Longer service life. The main reason wet batteries fail is due to the fact that water levels are not properly monitored coupled with the fact that they are not very vibration resistant. AGM batteries do not have to be constantly maintained and are much more resistant to both heat and vibration, which is why they offer longer service life.

Reply to
Larry Gadbois

formatting link

Strange that they are selling the OEM by mail order. The way I understand it, in the US UPS is willing to ship the Westco, but not the OEM since it is not sealed.

Leon

Reply to
Leon van Dommelen

On Sun, 08 Feb 2004 21:45:04 GMT, "Larry Gadbois" wrote in news:A5yVb.20074$ snipped-for-privacy@newsread1.news.pas.earthlink.net:

The M1 AGM battery has two discharge tubes, and the replacement I bought has the matching vents.

They aren't used in 'normal' service life like a wet battery might, but are there (according to the shop) in case of a big problem.

Reply to
Dave Null Sr.

I don't think the "vent" holes normally connect the battery innards to the atmosphere. They might have plugs designed to blow in the event of excessive pressure buildup for some reason. Like a freeze plug.

Reply to
Lanny Chambers

Dunno about the US 1999 Miatas, but the Canadian version was sold with a Panasonic AGM battery. The OEM replacement is an Exide AGM battery. The original did have vent tubes connected to the outside but as Lanny points out normally there is no discharge; it's a safety valve-like affair in case something goes wrong with the car's internal charging system. If the battery gets hot, excessive gas is purged through those tubes.

The Exide has no exit ports to which the tubes can be attached.

BTW, the Exide, fully charged but frozen overnight to -31C, started the car. Under protest, for 7 seconds, but it did start the car.

Reply to
Nora

My memory seems to play tricks on me. I distinctly remembered that the 'G' in 'AGM' meant 'Gel'.

Thanks for the writeup. I'll keep it around.

Reply to
Per K. Nielsen

I thought the OEM was sealed?

Oh, well. My memory has abandoned me.

Reply to
Per K. Nielsen

For several years, new U.S.-spec NB Miatas came with ordinary wet-cell batteries, not AGM, and dealer replacements were wet-cell, too.

Reply to
Lanny Chambers

This disagrees with what is said in

formatting link
]The Panasonic battery is vented to the outside of the trunk ]through a small rubber hose. This vent removes the hydrogen ]gas that can accumulate inside any battery during use. The ]amount of hydrogen developed during the use of an AGM battery ]is quite small when compared to a wet-cell battery. The WestCo ]battery does not have any vent, as it is sealed. WestCo claims ]the gas generation is so small, that venting is not required.

Leon

Reply to
Leon van Dommelen

Do you know exactly when Miatas started coming from the factory with wet cells?

Leon

Reply to
Leon van Dommelen

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.