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TR4/4A Miata Battery

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I have been contemplating a weight loss program for my Triumph and looked into these a little bit. That is certainly a nice price, lead acid batteries are nearly that much. One thing I read that gave me pause was they have issues with higher temps, and may be better not to have in a hot engine compartment. I didn't see how old the website was. Maybe this issue has been addressed or maybe wasn't an issue. I am guessing there are some active Miata forums that would have more real world experience.
 
That's pretty cheap for an AGM battery. 775 CCA will do the job just fine. AGMs have a reputation for longevity. The original AGM in my '92 Miata lasted 15 years. I put in an Optima replacement, which was in the car until about 2015 when I swapped it over to my RX-8. That's two batteries in over 26 years and the second one is still going strong. I put an Optima in my TR3, but for some reason, it only lasted about eight years. I probably wasn't diligent enough during the winter when the car sat in the garage. The Miata saw and RX-8 see more regular driving than the TR. I've since replaced the TR3 battery with a conventional lead acid type and bought a battery tender, and not just rely on recharging every once in awhile. Optimas are getting up there in price and didn't feel like spending that kind of money at the time when it went south.
 
I thought the price looked good for sure. What I question is the 775 CCA, everything else I found was around 430. 15 years is amazing, never got anywhere near that with a conventional battery, all the more reason not to concern myself with price. Heck in 15 years I won't be able to get in or out of either car, my eldest son will have probably taken away the keys anyway.
 
AGM batteries, IIRC, are more touchy than lead-acid when it comes to charging or jumping them. The traditional filling-station "quick charge" at a high rate is a no-no. Would suggest going over to miata.net and searching the topic there, as AGM batteries have been a source of debate over the years. The original Miata batteries (at least on the early cars) were, I think, made by Panasonic and were amazingly long-lived. Wish they were available here!
 
groupdeville said:
AGM batteries, IIRC, are more touchy than lead-acid when it comes to charging or jumping them. The traditional filling-station "quick charge" at a high rate is a no-no. Would suggest going over to miata.net and searching the topic there, as AGM batteries have been a source of debate over the years. The original Miata batteries (at least on the early cars) were, I think, made by Panasonic and were amazingly long-lived. Wish they were available here!
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There has been a lot of debate over on Miata.net (I go there almost everyday) about charging AGMs. Some truths and a lot of myths. Yes, the original that lasted so long in my Miata was a Panasonic. The Optima Red Top AGM that I replaced it with is still going strong after 12 years. Below is the recommendation from Optima on how to charge their Red Tops...nothing special here. You can rapid charge as high as you want as long as the temp of the battery doesn't go over their limit. Their Yellow and Blue Top batteries have similar re-charging procedures.


OPTIMA REDTOP® Charging Information

The following charging methods are recommended to ensure a long battery life. Always use a voltage-regulated charger, with voltage limits set as described below.
REDTOP Type: 34 & 34R - 34/78 - 78 - 25 & 35 - 75/25

These batteries are designed for engine starting applications. They are NOT recommended or warranted for use in deep-cycle applications.
Recommended charging information:

  • Alternator:
    • 13.3 to 15.0 volts, no amperage limit.
  • Battery Charger:
    • 13.8 to 15.0 volts, 10 amps maximum, approximately for six to twelve hours.
  • Rapid Recharge:
    • Maximum voltage 15.6 volts (regulated), no current limit as long as battery temperature remains below 125°F (51.7°C). Charge until current drops below one amp.
  • Float Charge:
    • 13.2 to 13.8 volts, one amp maximum current, time indefinite (at lower voltage).
    • Strictly adhere to all limits.


Other AGM manufacturers may have different methods of recharging, so check that out before hand.
 
Just FYI, AGM batteries are a type of lead-acid battery. Just a different structure from the more common, wet-cell or flooded battery.

I just replaced the Optima battery in my Porsche, which was in the car when I bought it in 2010. It was OK in most respects, but would lose its charge after sitting a couple weeks. As long as I drove the car regularly, it was fine, but I don't drive the car often, and I got tired of having to connect it to a charger before driving it. Once the battery was out, I saw the date code: 1998! So, it was in use over 20 years.
 
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