Nopstnz

Anyone know what would be a good replacement battery for our cars? Mine came with a Duralast, more like dura-don’t-last, that was put in Dec/18 and it is failing. I’ve had someone try to sell me a regular interstate battery but I told him I wanted to do some research. I searched through a thread talking about the OE battery specs and I looked up said battery and they seemed to be ones not applicable to our cars...

I’ve used Optima yellowtop in the past and it worked great for over 7 years but I’ve also heard since then that company was bought out and they’ve gone to garbage quality.

What batteries have you guys had success with?

furansu

I use and recommend Deka batteries. They have both normal and AGM variants (stick with traditional for the heat tolerance) and a couple CCA rating options in the form-factor.

Optima is now owned by Johnson Controls, and while their product is a 'good' AGM product, I've found they aren't durable, unable to tolerate any drain-down, with a short life, but a high cost of entry. Part of it may be quality control, but they market an AGM product to all use cases when in reality, a hot engine bay with no insulation/protection for the battery is a bad place to use an AGM unit. Standard lead-acid batteries handle it far better. If doing a trunk-mount, the Optima may be a good option again, as would any AGM.

wannawankel

Cheapest Group 35 battery I got was from Costco and made by Interstate. Two years and no issues even after it sat for 117 days (moving) and the battery was dead. Charged and working well ever since.

Nopstnz

Right?

I was getting quotes and kept thinking, "Why are car batteries so much pricier now than 6 years ago?"

Really appreciate your response. It was exactly the info I wanted.

Cheers

NotAPreppie

I agree with avoiding AGM batteries unless you relocated the battery to the trunk.

wannawankel

My Group 35 battery Costco is made by Interstate and is still going strong - even after two (oops) full drains and hot stop-and-go traffic in the Boston metro this Summer. I forgot and left the map light on for a week and charged it for 20 min, got the car started, and drove it hard all weekend in the Lakes region of New Hampshire. Sadly no RX-8 sightings and only 2 Miatas? I had a lot of compliments on the RX-8 at stops (hardly anyone knew what it was).

Frankly if I get two-three full years out of this battery in the RX-8 (given what other have said about the RX-8 battery torture test of a engine compartment) - I'll be happy.

Hi Flying 8

iTrader: (2)

+1
Interstates have been my selection for years and have provided seriously long life and even with a few instances of drain down. Everything from my company Sprinter to my multitude of Mazda vehicles.

Steve Dallas

I put a 24F Legend from Napa in my car in 2013, and it is still going strong. I think it was around $90.

UnknownJinX

I used an AGM unit on my RX-8 for two years without issues. It wasn't an Optima, though. It was one from Canadian Tire Eliminator line. My climate is fairly mild, but I go for Autocross and spirited drives time to time so it can still get toasty in there.

It might just be me, but I'd rather not have to deal with corrosion on batteries(which is a problem lead-acid batteries have, but not AGM). On my current car, I just had to have one post replaced due to corrosion.

Steve Dallas

I had 2 Optimas die after lasting 1 year each, so I went back to lead acid, hence the Napa Legend that is on its 6th year.

UnknownJinX

Mine was not an Optima and came with a 5-year warranty. I read about Optima's poor rep and made sure to avoid it.

Also, forgot to mention that I charge my battery once in a while just to be safe.

Steve Dallas

Mine were red tops and were hooked up to an AGM compatible trickle charger when the car was not in use, which was most of the time. Optima replaced the 1st one under warranty and refused to replace the 2nd one. No more Optima batteries for me.

[Come to think of it, my truck has a Walmart Neverstart lead acid battery with a 2012 date code on it under the hood.]

Rickster1823

Can someone drop a list of the top recommended batteries for the RX8s? i mean i was thinking an Optima as i have that on my 2013 GT and its been great for 3 years now.

I'm looking into replacing mine with something better than the duralast with high cranking power as well. My car still takes 3-5 secs to start and i have replaced plugs, coils, wires and starter in June.

NotAPreppie

Any big-brand BCI group 35 with at least 640 CCA.
Unless you have a special needs (like need light weight for racing, etc) just get a Napa Legend, Duralast, Interstate, Odyssey, whatever.

Mine had a cheap-*** Wal*Mart battery for 4.5 flawless years (and .5 slow start years) and then just the cheapest O'Reilly battery that would fit for winter duty (summer was a superlight LiFePO4). My LeMons Del Sol has a Duralast. My Miata has a Panasonic.

Seriously, any big-brand battery will have a warranty. Keep the receipt and make use of the warranty if needed but I doubt it.

Steve Dallas

Most car batteries are made in the same couple of plants in Mexico. They are basically all the same. Just buy one with the length of warranty you want. As I said above, I have a Walmart Neverstart 24F dated 2012 in my Tacoma and a Napa Legend 24F dated 2013 in my RX-8, and both are still going strong. They were chosen, because they were within a few blocks of where my batteries died, not for any brand or any other consideration. Duralast has been fine for me in the past, as has O'Reilly Super Start and Sears Die Hard.

Back to Optima... Three years is not all that impressive for a battery that costs $250. In my experience, that same $250 will buy you 15 years worth of standard batteries. Also, AGM does not do well under the hood of an RX-8. If you want to Run AGM, you need to relocate it to the trunk. I had 2 Optima Red Tops last ~1 year each under the hood of my 2011 GT. As noted above, I went back to LA.

Nopstnz

I ended up just going with one from Advance Auto, was an autocraft that was specced for my car. Honestly, I felt like it started strong the first time and each time after that has felt weak. Fortunately if it fails I can just get refund.

Steve Dallas

^ It doesn't sound like the battery is the problem. Have you checked all your grounds? Which starter do you have, and how old is it?

Nopstnz

Reviving my old thread in lieu of starting another.

My battery is new and works but it’s having trouble holding a charge. The starter tests good and the battery has a good readout but I had the alternator tested at Advance Auto and the voltage was mostly consistent but every now and then it would briefly drop low to around 11 then jump back up to 14.4. He wondered if that was happening during driving which was prevented the battery from charging up.

Guy at the store said it might be an issue with the regulator? I don’t know much about auto electrical stuff.

wannawankel

I just replaced my Costco 3.5 yo battery with another Costco Group 35 Interstate battery. Price: $78.95 - amazing. I replaced it early due to several reasons: water level OK but the recharge times vs. starting voltage were getting longer, had three deep discharges - one for 6 months due to a move/storage, and it's over 3 years (3.5 yo) since I replaced it prior.

boricua13

The alternator has a rectifier that converts the AC to DC, but in order to get clean DC voltage, it also has a voltage regulator. If that is failing, it could be the issue, but I'd start with the obvious, make sure your grounds are clean and tight.

onefastrx7turbo

RX8 alts aren't internally regulated; the voltage is controlled by the PCM

UnknownJinX

According to the Service Manual, there is a regulator component in the alternator, but it does look like PCM controls the voltage as well.

boricua13 has a good start IMO.