Has anyone tried ETX-9 8Ah AGM Battery
 

These batteries are really popular with Miata guys. In fact I've been running one in mine without issues. They weigh only 6.3lbs. The battery only has 120CCA's, so cold weather may be an issue. However here in SoCal it serves me well year round. The 8Ah reserve has never been an issue either since I start my cars often to lubricate them even if I'm not driving them. Is the boxer engine any harder to crank? I've been thinking about getting one for this car as well and saving the 20+ pounds off the front of the car to improve weight distribution. Thanks.

Cheng

Shorais are superior.

AGM is an older type that is no longer truly competitive with the LiFePO4 type batteries.

A 4lb Shorai has 27AH for example.

There's a vendor here that sell them with a nice bracket.

http://www.ft86club.com/forums/showthread.php?t=50947

Or the 3.5lbs Ballistic 16cell battery with 500 cranking amps.

https://scontent-a-dfw.xx.fbcdn.net/...83770075_n.jpg

Yes but this battery costs $30-60 depending on where you get it... not $300.

and also require relatively frequent replacement, and are dead if you ever discharge it.

I passed on the Deka when I got my Shorai a few years ago for that exact reason.

The Shorai can keep my radio on for 8 hours when I'm working on my car, and then start it without any issue.

haha yea that's how I killed one once. Went on vacation and forgot to put it on a tender.

Would a smaller one like the LFX09L2-BS12 or LFX14L2-BS12 be sufficient for starting? $100 for a 1lb lithium battery sounds like a decent deal. Thanks.

Cheng

It is, but you want to have about 4-5x the actual CCA needed to start if you don't want to tear up the battery. You'll end up replacing it as often as the Deka.

Think of it this way. What's the maximum weight you can lift? How many times can you do it? now if u went back 10%, how many times can you do it? Now, if you get a big buff guy, how many times can he lift your maximum weight before he gets tired?

I've been running my shorai LFX14a5-bs12 for 18 months now without issue. 2.3 lb $150 at batteries+

I had a Deka ETX14 on my autocross 89 Civic. As far as reliability, I installed it in 03/2010, sold the car with it in 11/2013 and it never died on me. Even with not being used for 3 months during the winter.


I did have a screw type disconnect on the negative terminal, that I used every time I parked it for the day. That probably had a lot to do with it keeping the charge for so long. I'm not sure how feasible that would be with a FR-S for radio memory alone.


However, for the FR-S I got the KC Machine kit that CSG Mike mentioned in his post. It is very well made and looks light years better than what I made for the Civic with stuff I got from Lowes. The battery is a little pricey, but you get what you pay for. I wouldn't put Deka ETX9 on a daily driver.