Zepticon

iTrader: (1)

Hi
So, lets talk some about batteries
Im looking at general input, advice and your view on battery options for the stock location battery tray,preferably AGM, and also anything related to the electric system surrounding the battery, starting and charging.

Introduction:
This weekend i had a go at putting in a Optima Yellow Top 51R AGM battery in the FD. I have the TurboJeff/GarageAlpha tray (which is awesome!) but i did not like the end result, so i am going back to stock (for now).
One issue was the mounting posts being to close to the edge so breaker box did not fit properly. Also, my Quick Disconnects did not clear the hood with the 51R. So ill archive the tray for later.

I have been running without the stock battery box" for a while since it has lost its shape and is just rattling around in there. Nothing is broken, it has just warped after 30 years of Rotary engine bay heating. My plan is to get **** sorted and use the stock tray, stock box and get a new stock top cover.

Battery size:
My measurements suggest it must be at least 180mm in height. Then a maximum of 175mm wide and 260mm long.
Extensive forum research have yielded some information, some says its a "Group 35" battery, others give the Japanese "65D23L" standard. But they are all more or less the same size and would fit the box. So as long as i get the outside dimensions, and make sure the + is on the right (R) side, its good.

Chemistry:
My thinking:

• Lithium: Im not going with Lithium (yet). Im waiting for the price to go down and the tech to mature. When all the old 911s around here start running it i will go with it as well.
• AGM: It is my preferred choice. The sealed box will help avoid the battery spilling corrosive **** all over the tray and down on the crossbar (that i am now gonna have to repaint for the 2nd time due to this). Also the AGM can handle more abuse and that will help on a car that is not used much, and that sits all winter with a disconnected battery. Its also just an improvement over the regular Lead-Acid battery, not a new tech like Lithium.
• Lead: Regular old stuff. Will go bad if discharged and is prone to leaking and ****.

Actual batteries:
Here is where it gets more difficult...

VARTA Silver Dynamic D52 AGM, 60Ah, 680 CCA - This is my preferred choice after a few days of research. "Made in Germany" by an OEM. I don't see much going wrong here. What i really like is the recessed connectors that work well with quick disconnects. Its also nearly half the Price of the Optima Yellow.


Optima AGM Yellow Top, 48 Ah, 660 CCA - Used to be good, now seem to be suffering from "resting on old laurels" syndrome or something as they **** themselves to quickly.



Charging system:
I have read up on modifications to the charging system. A high amp alternator is on my to-do list, same with improved grounds and a general refresh of the starter and charging harness.
Some mention diodes to bump charge voltage but i am not sure if this is needed yet. The car is stock (for now) but there are modifications coming that would require more (electric) power and then this will be addressed.
Any other advice here is welcome

arghx

iTrader: (3)

Here in the US you can go to a standard auto parts store like Autozone and get a "Silver" battery with a 2 year warranty just by giving the vehicle info to the guy at the parts counter ("I need a battery for a 1993 Rx-7 please"). It's just an off the shelf lead acid battery that fits right in the stock tray. It will start in the middle of winter (I live in Michigan, so not quite as cold as Norway, but it's still cold). Most of the batteries here are made by Johnson Controls and sold under various brand names at different stores, but they are pretty standard lead acid. The "Gold" batteries with 3 year warranties are slightly wider due to extra plastic and don't fit in the stock battery box.

I've had bad luck with Optima batteries. Lithium ion - as various threads have discussed, whatever solution you get needs to be designed to work with a 90s japanese car electrical system (dumb alternator with built in regulator that could then interface with a lithium battery that can balance its internal cells and not discharge/die or catch fire or something).

If you can keep a stock sized battery and not relocate it you won't have too many electrical issues to worry about. When you see people running tiny motorcycle batteries under the hood or in the storage bin, well no wonder the electrical system is stressed. Even Miata batteries suck. Really the stock electrical system isn't that bad.

DaleClark

iTrader: (55)

I've never been pleased with Optima batteries. I think they are mostly hype. Some people have had success but I've seen way too many cases of early death or weird problems that turns me off.

One thing that can help the fit of the battery in a stock terminal situation is to unbolt the positive termininal from the fuse block and rotate it 90 degrees. You do have to cut a tab off the fuse block to do this. This will fit the fuse block tighter to the battery and get a better fit.

I've been running a Miata battery for years due to my front mount IC. Fortunately it doesn't get cold where I am but if I let my car sit too long it will get super weak. I did find a current draw that wasn't helping at least .

As far as cranking speed it's fine when it's in good shape. It just doesn't have the reserve if the car sits a long time.

Dale

j9fd3s

iTrader: (3)

The stock battery, in the US was a 65D23L either Panasonic or GS. we take the Japanese battery size and give you something close enough.
Right now Mazda USA will sell you a 26R from Interstate with a nice Mazda sticker on it.

i went down the battery rabbit hole too, and i haven't bought anything yet, but the PC680 looks good, still a 1990's price.
i'm waiting for my battery to die, i'm running a 1U something or other for a golf cart, 300cca, like the original battery, and it was $40
#short arms deep pockets...

provels

My battery experience... From what I see from distributors, they spec a 35 for the manual and 24F for the auto. Either way the car won't hold a grudge. I have a standard flooded 35 from East Penn (via farm store brand) in my auto now, dated 2010, still working fine, though I have let the clock, etc. run it dead several times. $100/7-year prorated. I did add one of those battery cutoff switches to it a few years ago and that works great. I pop the hood anyway when when I park it (garage) to get the heat out and just spin it open.
Top Post Battery Master Disconnect Cut Off Switch | eBay

I suppose you can go AGM, but after 50 years of driving, I still haven't seen the need. Maybe if I was 4-wheelin' in the woods or camping.

I don't know if anyone has the measurements for the Panasonic, but here's a spec sheet from East Penn for comparison.

Zepticon

iTrader: (1)

My preference for AGM is the main selling point of the early Optima batteries, that they are sealed and can be handled without the risk of spilling. Being able to store them in the house and charge them without gassing is king.

But as mentioned by many, Optimas dont so good on the hype. Thats why im thinking the Varta AGM is a good choise

jza80

iTrader: (32)

I've had great luck with Odyssey, I installed a PC1200 in my FD in 2014 when I bought the car. At that time, it was modified for a rear bin location and the PC1200 was the largest batt that would fit in the bin. I have since un-modded the car to restored the battery back to the stock location with the same PC1200 battery (and some spacers to make it fit firmly in the battery box since it is a little small). After 7 years it is still working and testing great.

R-R-Rx7

iTrader: (24)

im in the same exact position.

I ended up getting the bosch s5004 which i believe is the same as the varta you posted . 075 size
these quick disconnect will not fit this battery. you wont be able to open them.

Zepticon

iTrader: (1)

Yeah, Bosch and Varta are the same form what i can tell, just different stickers. The S5004 looks to be the same size, just not AGM. From the looks of it the AGM version is S5A05.
Why do you think it wont fit? My current battery have the same type of recessed mounts like this have, and that works pretty good. Its really nice to just clip them of when im not gonna use the car for a while, since my alarm system drains the battery if it sits for to long.

Sgtblue

iTrader: (16)

Weird, for almost 20 years I’ve used a stock-size off-the-shelf battery with stock terminals in the stock position. Fits perfectly clean with the stock box and cover, which are also at least 20 years old. Never had any issues with leaking or spills, never had to repaint anything and consistently got over 5 years life before signs of slow starting. I HAVE used since early on a Deltran battery maintainer over the winter or whenever I anticipated not driving it for me while. Some years ago I also put a relatively heavy gauge red wire in parallel to the alternator while installing auxiliary grounds.
No big stereo and only mildly modded.
Never felt any need for anything more.

R-R-Rx7

iTrader: (24)

i might have given you the wrong p/n because the s5004 is a 61ah but the one i got is the 60Ah gel battery. Let me get back to you on that.

With the recessed battery terminals theres no room for the quick disconnects to open up. They dont bolt down like regular terminals. The lid is whats clamping down the terminal on the post. I bought a set with the same intention but it doesnt fit . If yours has a little more room so the quick disconnect can open up then it will work. I have bought slightly different ones so yours might have a smaller profile

Worth noting that i have them facing forward with my current setup. Perhaps thats why it wont fit

Mazdabation

iTrader: (9)

All this scientific battery talk.... I just went to Costco and bought a Kirkland! Lol
Fits in stock location no issues, and good ol' Costco warranty

Zepticon

iTrader: (1)

Hahahhaha this made me laugh. I have spent more time on this bloody battery buying business than i did buying my house xD Guess thats why i never get anything done

DaleClark

iTrader: (55)

I have a feeling you may have fewer options in Norway than we do in the States, though!

Also, FYI, those quick disconnect terminals are nice BUT the "clamp on the battery wire" design will have problems after a few years. Corrosion gets in there and you start having problems. Having a proper crimped on connection is the best way. They are convenient, though. Lots of us ran terminals like that back when I had FC's and we all had varying degrees of problems with them over time.

Dale

j9fd3s

iTrader: (3)

this made me laugh! also true! funny part is that the house is great, but i haven't bought a battery yet

j9fd3s

iTrader: (3)

not sure about that, there are only a few battery plants (i want to say 3?), so most batteries come from the same place and just have different stickers on them. its like brake rotors (2 factories in the world), or coolant (3 in the US).

Zepticon

iTrader: (1)

We have very little brand overlap with you guys. Optima is one that have found its way in to stores here, but thats it. Oddessy is possible to get through specialized stores that do batteries. We dont have Amazon here (yet) so there are a lot of different webshops for all different kind of stuff. Its very difficult to "go and have a look".

I know Mine are getting green and corroded already. But i will "at some point" replace them with new ones that are plated, and then solder the cable in place.

DaveW

Be careful soldering. Too much heat can soften copper wires, possible leading to fatigue and breakage at the clamp.

Zepticon

iTrader: (1)

So, i ended up buying the Varta AGM battery.

And as every other battery sold over here it is not exactly right. The biggest issue is that it sits to low in the battery box to make it an ideal fit. The box have been in a box in the attic for a few years, and now i remember why The issue is that the wires going to the fuse box at the + terminal ends up interfering with the battery box, and i cant get it to fit.

Here i have two options:

1. Lift the entire battery up 1-2 cm for better fitment
2. Use a longer bolt between the battery connector and the fuse box, and then ad a few nuts for spacers to get the required height.

I will try both options and see how it goes.

Also, due to the battery shape, the stock battery tie down does not work with this type of battery.
So the last week i have spent making different prototypes for a new tie down that i will have machined from aluminum.
First i made a bunch of the trapezoids to dial in the exact placement of the hole for the tie down rods, then a few attempts with the larger square to fine tune fitment.
It must also not be to large to fit on the battery with the battery cover on.

The rods are from the "civic" 51R battery kits you can get from china. I cut them about 1" shorter and tapped new threads since they are hollow and perfect for an M6 bolt.

scotty305

iTrader: (2)

I think AGM is the way to go. I've had AGM of various sizes, currently running a Miata size AGM. I went the cheap/easy route with a lead-acid battery once and have been kicking myself ever since it leaked battery acid during a track day.

Zepticon

iTrader: (1)

Yeah mine to. As mentioned above, i have gotten acid corrosion on the crossmember holding up the battery, intercooler and airbox. I am not buying something else than AGM for the future.

R-R-Rx7

iTrader: (24)

it took me a while to get back to you with the battery p/n. it is the AGM version of the s5004 and the p/n is s5 a05.

sorry been out of the country. i think it is the same as the one you got there.

The battery tray/tie down looks good

djseven

iTrader: (56)

Wish I would have seen this sooner. I bought an Antigravity 51R size Lithium Ion Battery last year. It was the best $700.00 I have spent on the FD. 1200 CCA combined with the rx8 starter makes the engine start instantly and I can mess around for an hour with the key in the ACC position and car not running and the battery seems unfazed. The fact it weights 9lbs and fits in the Turbo Jeff Battery tray is a huge plus as well.

TomU

iTrader: (11)

Think you mean lithium iron. Big difference

https://blog.epectec.com/lithium-iro...and-advantages

I agree though. What's another couple hundred dollars when you own an FD. Only thing is I believe they are temperature sensitive (i plan to mount mine in the storage bin) and they don't like being over or under charged. AGM is temperature sensitive as well. I had an AGM factory mounted in the trunk of my BMW and it kept going dead in the winter. I also agree with Dale. I had an Optima red top that didn't last a year. Changed out with a Sears AGM that's been in the car for well over a decade (probably back when Sears sourced from USA manufacturers )

Also, not sure i'd rely on a plastic mount. Looks nice, but strength would be questionable

djseven

iTrader: (56)

https://antigravitybatteries.com/pro...ive/ag-51r-rs/ They label them as lithium ion and honestly I have never dug into it any further than that. But you are correct, in the overall cost of ownership of these cars its minimal and its been flawless to this point.