wallyman

Need to replace the dead battery in the 92 getting the LS2.. what's the current thinking?

1. OEM AGM Battery Marathon, 25AH, 320 CCA (too small I feel)
2. OEM AGM Battery, Westco 31 Amp Hour, 475 CCA
3. Optima D51R Yelowtop, 450 CCA (Had this, not overly impressed as they die early)
4. FM uses a "C6 Corvette Battery" which appears to be a standard lead acid with vents (BCI 85 or 90), 590CCA
5. Odyssey (as seen in the Targa) PC925 , 330 CCA (seems small but..?)

The Optimas seem to have fallen out of favor, I've killed a couple in under 3 years as well. I think stock AGM is a bad call, it's designed for a much smaller load that the engine or my stereo will require. The stock '13 Vette uses a 590CCA, seems like I should be aiming for that level. I see some nice options in the Odyssey and given I am rewiring the car I am not limited to the reverse terminal unit Keith used.

I prefer AGM/sealed over acid.. so leaning towards the Odyssey. I need to do some dimensional checking but I think I have a 35 series in the 94, so pretty much any one fits depending on the CCA I want and the footprint I can stand to get it.

Thoughts and opinions?
Wallyman

MX-Brad

I have a 51r (honda civic battery) in mine. 440cca i think. Works fine in my application, but i just have stock radio and electronics. I seem to kill the agm's too frequently and they're stupid expensive here.

wallyman

That is the dead one I am replacing, ironically. It worked ok but after a little while it started to go dead if I didn't drive the car every 3-4 days.

movieboy4fun

I used the same battery as my E46 - M3, available at wally world, has built in vent tubes and was exactly the same battery shape as the OEM BMW battery but 1/3 cost at wally world. Been working flawless in my M3 for last 5 years so for $144 Canadian I picked up another. It is larger than the stock Miata battery but nothing a new battery holder won't fix.

Didn't go Gel Cell as we are constantly replacing them in the Go Fast boat shop, lucky to get a year from them but to be fair, at 140 MPH they do take a serious beating.

Dean0

wallyman

Dean0 thanks for the info! I'm leaning towards the Odyssey PC1200.. it's the bigger of the two the Z06 guys use, and dimensionally looks like it will work just fine with a hold down bracket designed for it as opposed to the stock Mazda. I need to mock up a cardboard box that size and see how it looks, and terminal placement is also a concern. I am adding a primary fuse block to the trunk (stock FD RX7 unit) which hangs off the positive terminal, but it has not arrived yet. Once it gets here and I can make a template I'll report back.

My last battery in there was a Optima 75-25 and before that the D51R.. both died young (under 3 years). I am hoping the Odyssey, being geared towards racing, will be more forgiving and give a longer life. They are dry cell Absorbed Glass Mat (AGM), not gel. Price-wise the 925 runs $150ish, the 1200 runs $199ish so comparable to the optima at least around here.

.boB

I'v had a Optima red top in my street/race Cobra for years. I'v left the battery on a few times and run it down to zero. I used an old fashioned battery charger to get it going again more than once. Still going strong.

That being said, I think I'm just lucky. CR doesn't rate the Optima very high, and they are kinda expensive. I use one because the battery is on top of the passenger foot box. In case of a crash, I don't want acid leaking out.

The Exocet gets a small Braille battery; only weights 15 pounds or so. Seems to work fine in that car, but it is very minimalist car. A lot of electronics, but not many lights and no electric accessories.

movieboy4fun

Just to add one more possible option, the CSL E46 M3 has a smaller lighter battery, albeit still lead acid. A good friend of mine has a CSL so I asked him where he got his new battery as the BMW dealer list NADA for CSL parts, I know. He informed me the new Mini Cooper S cars have the same battery as the previous CSL's. Off the top of my head the CSL battery is about 3 inches shorter but still fits in the stock battery box fine, also has vent tube hookups.

Stock M3 - Group 94R - 46lbs - 575 CCA
- Group 49DL also works but not listed

CSL / MINI - Group 47 600B - 34lbs - 480 CCA - ( possible worth checking, I didn't)

I know my friend has the CSL bug and is happy he shaved off 12 lbs and everything works fine as before, no issues. Not sure if available outside of BMW, as I stated this is fresh from memory after talking with friend so please check online to verify details.

Dean0

wallyman

My attempt at a table of the battery choices I was looking at. Mockup I am using the Optima 75/25 as I had one handy for reference. I know it fits with the fuse block I going to use. Every battery considered is AGM.


BRAND...................MODEL...CCA.....L.......+/-.....W.......+/-.....H.......+/-.....WRNTY...SOLD.WHERE
Stock.(Westco)..........Miata...n/a.....7.80............5.10............7.20........ ....n/a.....n/a
Odyssey.................PC925...330.....6.64.....1 .16...7.05....(1.95)..5.83.....1.37...36......Onli ne
Odyssey.................PC1200..540.....7.87....(0 .07)..6.66....(1.56)..7.60....(0.40)..36......Onli ne
Optima.Red..............75-25...720.....9.38....(1.58)..6.81....(1.71)..7.75. ...(0.55)..36......Autozone,.Advance,.Amazon
Optima.Red..............35......720.....9.38....(1 .58)..6.81....(1.71)..7.75....(0.55)..36......Auto zone,.Advance,.Amazon
Exide.Edge..............35......650.....9.06....(1 .26)..6.63....(1.53)..8.83....(1.63)..48......Onli ne
Deka....................9A35/85 680.....9.75....(1.95)..6.83....(1.73)..7.75....(0 .55)..30......Online
O'reilly.Super.Start....35PLT...680.....9.56....(1 .76)..6.75....(1.65)..7.75....(0.55)..36......O'Re illy
Duralast................35-AGM..680.....9.50....(1.70)..6.68....(1.58)..7.75. ...(0.55)..36......Autozone

+/- as compared to stock replacement Westco. (x.xx) is increase in dimension.

So my thought process:

Stock - not enough for the V8 and my stereo crap.
Odyssey - lots of love for these, but concern over warranty support due to online purchase. Smaller footprint was a plus.
Optima - just garbage anymore and not worth it for the 40 CCA you gain over the 3 second place ones.
Exide - liked this on paper (4 year warranty) but online sale means warranty concerns.
Deka/O'Reilly/Duralast - pretty sure these are the same guts with different labels.
Deka - online sale means warranty concerns.
O'Reilly - price was $199.xx out the door.. but...
Duralast - $176.xx out the door with 20% coupon in email today for autozone, so bought it.

Dimensionally it is almost identical to the Optima 75-25 I am using for mock up, so I believe fit won't be a problem. 0.12 longer and 0.13 shallower.. might as well call it identical.

CCA is tied for the second highest and losing 40 CCA to the crap Optima is no loss.

Price at Autozone with the 20% off coupon in my email today I was out the door at $176.xx including the $18 core charge. Turn in a crapper battery and you are $158.xx.

Warranty - 3 years is not bad, if I am going to have trouble it'll be in the first 2 years. Local support, just drive 5 minutes and swap if I do have problems.

Going to test fit tonight and see how it looks. I'm excited to get this solved as it is holding up the wiring. Plan to start at the battery and work forward so it's all laid out correctly. Photos forthcoming!!