Can't be that hot there, the PLASTIC washer tub is there, but nevertheless the Odessey PC680MJT is a special metal jacket hi-temp (-40C to +80C) battery. As for mounting: "Battery Fixed Position Bracket, Fits ODY-PC680MJT, Brushed Aluminum, Universal, Each - polished, ball-milled battery mounts attach to any flat surface." buy it here -> http://store.summitracing.com/defaul....asp&x=37&y=15


I like my big brakes - so no go to 16" wheel version - 17"ers will work on the big brakes, and they're pretty darn light - smthg like, for example, the Motegiracing Trak Lite's 17x8s are 14.5lbs (forged) saving a nifty ~7lb/wheel = 28lbs, not to mention the unsprung rotational weight improvement.

I got it from http://motors.search.ebay.com/_W0QQf...dysseyQ5fworld or
also available at www.portablepower.com just make sure to get the SAE posts w/the battery if you want to use the stock auto-type battery terminals.

The PC680MJT will fit just fine in the existing battery box, and that's a good place for it without adding any hassle to the install. Putting it on the firewall will improve the polar moment of inertia of the chassis - after all that big 27lbs of OEM battery is AHEAD of the front wheel line and that's quite a saving to get that back between the wheelbase. But even reducing it to 15lb out there is also good.

I think I'll sart out just keeping it in the OEM box as well, until I decide to do the move, which is admitedly a bunch of work, all told.

 

The fasted way to shave lbs of the car would be as I have found

Racing Seats - $500x2 - 32lbs (60lbs if you went with bucket seats)
Battery - $100 - 15lbs
Midpipe - $400? - 20lbs
Wheels & Tires - $3000 - 30lbs
Ti Exhaust - $1200 - 25lbs
Power Pant Frame $? maybe ~$1000? - 25lbs


That right there gets you in the neihborhood of ~150lb, without stripping the car sans seats. Obviously, you've also bought your self a turbo kit and then some in terms of cost.
The top 3 get you almost to ~100lb (with the racing buckets) for about $1500. you could prolly go with the greddy exhaust and still save about 10-15lb instead of the ti for another $500. To really feel the difference, you'd need to lose about 200lbs (think of driving the car with and without a pasenger).

Now, the wheels, in terms of performance bang for buck, would prolly give you the biggest "feel" difference in terms of handling, steering and response.

I'm still working to find other weight savings avenues. I'll pass on what I find.

 

You guys are amazing. I'll just watch you all as this still has to be a daily driver, and part of the deal with my wife was the back seat for the future (meaning child seats).

how much do the air bag systems weigh? If you're using it for racing, wouldn't you want to remove them? also a lightweight steering wheel?

 

At least for me, I want to cut weight but not stip the car.

The back seats stay
The front seats stay (maybe...I just think raceing seats are not comfortable?)
Airbangs
AC

They all stay, I"ll just cut as much as I can without breaking the bank too much or removing interior stuff. Unsprung weight...is the key too, getting rid of that will really help!

Hey, I heard the base RX8 weighs 3000 pounds instead of the normal 3050...is that true???

 

my base car on a cat scale fully fueled with out me in it weighed in at 2960lb. (see my pic of the sheet in the garage). I've got a true base model, no DSC, heatlights, leather, stereo etc...

 

Got the Battery today - and it is SMALL. Check out the pics. 680 PHCA, 220 CCA, nice metal shell over the plastic case, 15.4 lbs. Should make it easy to find a nice place for it next to the firewall

 

wow, that is tiny. never seen a car battery fit into someone's palm before. ok, not quite you palm, but you get the picture...

what is the rating compared to the stock battery? is there a greater risk of it being drained quicker?

 

There's an alphabet soup of ratings for batteries, that's why different ones are hard to match up, one to another. I've never figured out what the capacity of our OEM battery is, one thing I know, it's a terrible battery.

Mine is only staying charged about 4 days at a time recently . In fact at 8:30 this morning it's off to the dealer to get a replacement that they say is about 3 times the capacity (!) of the flashlight battery they put in there at the factory LOL. There's a TSB on this I think.

Odessey batteries combine unique attributes that make them ideal for race cars or cars used on the track, which is what I got it for, i.e., weight savings/better chassis placement options. For example, very light weight/small size/excellent vibration resistance, very high short duration cranking amps, repeat deep discharge cycling, quick charge rate, are just about everything you could ask for in a battery for this use....except....

The only thing these batteries don't like are parasitic losses - and our 8 has these parasitic loads in the constant drain of it's computer, so if it's your full time battery either use the car regularly or use a trickle charge / disconnect for longer-term non-use (e.g. 18ma for 26 days reduces PC680 to 30% charge). Not a problem in my mind for my use.

PC680 16AH (Ah @ 10 hr rate) ratings:

5 Sec Hot Cranking Amps (HCA) = 680A
.... pulse discharge in amps to 7.2V - 5 sec. @ 680A 10 sec. @ 595A 20 sec. @ 525A
Cold Cranking Amps (CCA) = 220A
Cranking Amps @32 (CA) = 300A
Hot Cranking Amps @80F (HCA) = 370A
Fast charge @50A for 14 min = 80% full capacity
Weight (with hi-temp metal jacket) 15.4lbs

Edit after new battery install: the new battery I got is a mother of a thing....hardly any space left in the battery box and the specs are: CCA = 680 CA = 800. If that doesn't start it nothing will! But it must weigh a ton...

 

I have been looking for the battery you bought and it says its a motorcycle battery?!?

 

Possible - it's a similar size. But go www.portablepower.com look at odessey batteries, there are lots of specs about them there, look for PC680MJ. Go to the spec sheets there and one of those has a replacement quide - this matches for quite a few car battery sizes. In the end a battery is a battery is a battery.

Also remember, my application is aimed at track use... battery application rules are out the window... but this battery makes a decent attempt at being all things to all the car needs - not the be-all end-all, but the point is reduce battery weight a bunch (~15lbs), move the weight that remains behind the front axle line (lower polar momemt of inertia), all in the quest to improve handling and increase performance.

 

/\ /\ /\ /\ /\ /\ /\

I like it. The 8 rev's like a bike. Why not a bike battery.

 

A lot of people do the lighter rims and smaller rims, but what they don't do is get lighter tires. You can lose a few pounds there, you can get them when your stock tires ware down if your trying to save money, but you mine as well go for those if you have to get new tires any ways.

 

You should've gotten a Batcap 800. It's 1.4 lbs lighter and more powerful. Motorcycle batteries don't work so well with cars.

http://www.batcap.net/Model800.html

 

By the way, in that picture you attached is that an FD engine in your rx8 or just the manifold?

 

That's why I got the Toyo T1 S tires vs. the Falken FK 451's. The Toyo's are like 2-3 lbs. lighter per tire than the Falkens or the OEM Bridgestones. I got them from :

www.edgeracing.com

What's cool is they have the weight of the tires on there. Good prices too.

 

My guess it's a very similar battery or perhaps even the same, as another Odessey battery. Compare these two batteries to see what I'm talking about. Here---> http://www.portablepower.com/items/s...LA/1/all/pc680

The PC680(no MJ) is 13.5lbs, the PC680MJ (metal jacket) is 15.4lbs.

Same specs BUT with a vital improvement made, and very important for us and why the PC680MJ is NOT just an ordinary motorcycle or audio battery. The metal jacket isn't needed for audio application, say in the trunk, like that company describes, but is needed under the hood, where it gets HOT.The metal jacket makes the PC680 a high temperature capable battery, which is what we need with a HOT rotary engine nearby.

As with most mods, I've discovered the devil IS in the details (if you want to do it correctly, not just slap something together)

PS. That's not my car in the pic ...sighhhh - but oh I wish! :D

 

I emailed batcap to ask them about that and see what they say about how much heat it can withstand.

How does your car run with the motorcycle battery? Has it been hard to start in cold weather at all yet? Any problems with volts?

 

Can't tell you yet. I got the battery last week, the washer juice-bag style replacement Monday, and the billet aluminium battery holder will arrive in a couple days. Once I find the exact spot for it, I need to measure for extension of the cables.

Probably do a DYI on it so look for that.

12 Volts is 12 volts the world around, and as this puts out 680 amps for 5 sec, just a tad less for up to 20 sec, this is way more amps than OEM battery, so no starting problems anticiapted.

Hell the monster battery the dealer just put in last Friday when my OEM failed is only 680 amps!, and that looks to weight well over 30 lbs. The difference is in how long the battery will run a high load on its own (like wo/motor running and your cranking an 800 watt double sub and stereo at 110db all afternoon in the driveway, for example). :D

 

Well, I ask because I know plenty of FD guys run odessey batteries and have issues, especially people with alarms. Like if you leave the car sitting for 3 days or more they'd go to start the car and the battery would be dead. Or in the winter they'd have lots of starting problems.

I was talking to one FD guy over PM's and he said he completely killed about 3 odessey batteries due to those problems continuously happening.

I just wonder how it will work considering the rx8 has a lot more electrical stuff compared to FD's yet the alternator for the rx8 is the same amperage as the FD one.

 

The problem you are talking about is 'parasitic loss' or basically, things are running in the car all the time, even with the key out of the ignition and it runs the battery down! And yes these small batteries are susceptable to this as the total amount of energy they store is less. Their special contruction lets them give high starting current, allows many deep discharge cycles, nearly unlimited inrush charging current for quick charging, etc., lots of good stuff.

The one thing that the physics & chemistry of these batteries doesn't do is give the ability to run a load over a long period with recharge. If you read the manual / specs they, in fact, specifically re-wrote the manual high-lighting this, and insisting that if this is the case (leaving the car for a long period like 14-30 days) and you have parisitic losses, that you must either disconnect the battery or use a low cost 'battery maintainer' charger when the car is just sitting there. The good news is most people use their car relatively often, daily or every few days anyway. Then it's likely a non-issue.

Bottom line "this battery lunch is good, even excellent, but it ain't totally a free ride, so go in with your eyes open, then you'll have no surprises. Which i am.

 

I know what parasitic loss is and I agree with you on all of that. I guess we can't say for sure what will happen until you put it in and use it for a few months, I'm just interested in how this will work out. Like you I am always looking for things to remove or reduce weight, my 2nd gen NA currently has 250 lbs of weight reduction with full interior still, but I don't think that will be as easily obtainable on the rx8.

 

250 lbs! that's a lot! As you can see we're struggling with losing 100 lbs. The more you look at the 8 you realize there is very little waste there, and there is not much weight (or structure) outside the wheel base to lighten.

 

All the things I removed the 8 has too, you just have to be willing to sacrifice.

Some of the major things on my list for my 2nd gen removal are:

AC
PS
All emissions equipment
All sound deadening mats
3/4 of sound deadening tar
Radio antenna/motor/wiring (I have an mp3 player anyways)
Washerfluid bottles
Front tow hooks (too low to use them anyways)
Front speakers (only handled the highs in music)
Storage bins
Spare tire/jack/etc

The list goes on. I basically chipped away anything and everything that the car didn't need or I could live without, and I still have a full interior.

Would I remove things like PS and AC on my 8? Probably not, but the 2nd gen is different. My AC didn't work anyways, and manual steering on the 2nd gen isn't bad at all.

 

I know of someone with a first gen rx7 that took out his starter motor and battery. Then he took a big snowblower's pull start mechanism and attached it to his e-shaft pulley. That'd save you the 27 pounds and you'd also lose the starter weight! Just don't stall the 8

I wish I could find the pictures of his setup...

FS

 

They just got back to me and this is all they said:

Hello Drew,
Yes, the model 800 can withstand engine compartment temperatures. We appreciate your interest in our batteries and if we can be of further assistance, please call us at 334-692-4650 or email us.
Sincerely,

Ray McKenzie, President, Xstatic Corp. HOME OF THE BATCAP