A dry cell battery is much lighter than a conventional "wet" battery. This is an easy mod for those who want all-out performance.

http://www.odysseyfactory.com

 

just make sure you have a jumper cable if you live in cold weather

 

how much of difference in weight does it make?
also why do you say that it'd be hard to start during the winter?

 

...i don't think jumping a dry-cell battery is a very good idea... nor do i think that tempurature is as detrimental to a dry-cell reaction as it is to the Pb + H2SO4 wet-cell reaction...

anyways, the difference (considering that for each cell in the car battery consists of a big lead plate and a lot of acidic water) in mass can be big... +30lbs in some cases. also, with a stand alone system like this (as used in race cars) you may be able to eliminate the alternator (i don't know, does the ignition run on DC or AC??) for more weight savings, etc.

 

dry batt doesn't hold charges as well as wet is what i was told

but you are better off trusting Wakeech than I

 

i'm pretty sure all power running through the car is DC. The only place it would be AC is in the alternator coil. There is a rectifier inside the alternator that converts AC to DC and that then goes to the rest of the car. I don't exactly understand how a dry battery works but i assume a chemical reaction takes place so it would eventually die; possible very quickly w/o the alternator. Of course if you are going all out for one drag down the track then using a dry cell and removing the alternator could save 50-60 pounds. That's alot of fat to trim and may be worth it for the die hard extreme racer.

 

I don't know how good dry cells are now days. But for 1 they are more expensive. 2. If they go dead, they don't last very much longer after that.

I had a car that after the first 4 years, went through 2 dry cell batteries. I finally went to a wet cell. And it's lasted much longer than the dry cells ever did.

 

I went to a drycell Odyssey PC680 (it's small) to make room for my intercooler. So far so good for ~4 months, it's saved me 15-20lbs over the stock Group 24 battery.

 

honeslty i would just move the battery to the trunk and keep it wet. That way you can improve the weight distribution and free up a good amount of space under the hood

 

OPTIMA batteries feature two thin lead plates wound into a tight spiral cell, with an absorbent glass-mat in between to hold the electrolyte solution.This unique design allows for more power and increased energy, resulting in quick, reliable starts. OPTIMA batteries are the first and only batteries to feature SPIRALCELL TECHNOLOGY.

· It'll last up to 2 times longer than other batteries.
· It can sit unused 3 times longer than other batteries.
· It is over 15 times more resistant to vibration than other batteries.
· It's nonspillable and can mount in almost any position.
· It provides constant performance quality keeping your battery running at the same level even as it's being discharged.
· It provides more power in the inital 1, 3, 5, and 10 seconds of the vehicle starting process than comparably rated conventional lead acid batteries.

http://www.optimabatteries.com

 

The Miata comes with this kind of battery. It's located in the trunk, on the right a little bit forward of the rear axle. It's pretty light and small. The original stock panasonic battery I didn't have to replace for 5 years. I replaced it with an optima battery and I'm on year 4 with it. I've been able to start the car when it was below freezing without a problem also. So longevity and durability issues aren't a concern. In fact I find it more durable then lead acid batteries and the lighter weight is a nice bonus. The con is the price, nearly $70.

Mazda went with this because lead acid batteries give off hydrogen. I guess they were worried that the trunk is too well sealed and there might be some danger. So putting a "wet" battery in the trunk could be dangerous... I have heard other Miata owners putting a wet battery in the trunk with no problems as well.

I don't recall where the battery for the RX-8 is located. Does anyone know and what kind of battery it is?

 

Optima is neither wet nor dry

it's gel and it's sealed so it doesn't give off any gas

also, it's the only battery you can mount which ever way, even upside down i think

i run optima red top in my wrx, definitly no weight saving, but CCA is better than stock

did i mention it's rechargeable?

 

I think only the old Miata batteries were gel cell. My '99 uses an absorbed glass mat (AGM) battery that has a hydrogen vent. The AGM batteries are quite light.

 

Can this type of battery run in extreme cold situation ? Once or twice per year it can go to -30F in cold days of Winter.

 

...on another tanget: this is one freakin' cool battery... the reason that batteries go flat is that the PbSO4, which forms when you're drawing current, is pretty flakey stuff, and if it falls off the lead plates, you loose that potential to re-store energy in the cell and thus deminish the capability of the battery... if it's a long start on an old car, and someone bumps you (or you hit the brakes real hard) backing out of yoru driveway, you can kill your battery no prob.

 

The Odyssey PC1200 automotive version at 38.2 lb and 550 CCA is heavier and weaker than an Optima 35 (33.72 lb, 720 CCA).

Good thing I can whip out the rotary common sense to break down these nonsenses.

 

Is this a record for thread resurrection?

 

It would be interesting if the prior participants in this thread were to report back on how their batteries lasted over the past five years.

Ken

 

Would the Kirkland R51 work with the Rx8? And does anyone have a link for a smaller battery tray? I made this mod with my FD and save probably 15 lbs.

 

Not even close.

 

But here's the scoop! 35 lbs is not even light.

You can get the 8lb or 12lb version.

12lb is ok for summer if you do not have an AMP with a big stereo system.

 

^^ was just faced with this situation, but chose to go with the pc925mjt over the pc680.
it can fit mounted on its side with a few minor modifications such as stretching the P+ cable and shimming the tie-down. future adjustments for a perfect fit seems inevitable tho...

not the best in weight savings, and CG isn't affected too much. but its a stronger CCA battery and requires somewhat minimal mods. its 24.5lbs actual.

 

I just installed the PC680, which weighs about 16 pounds.

 

Hi guys,

I am a little bit lost with all those battery. Mine went down yesterday and I need to buy a new one. I saw on all threads that the pc680 seems to be a good choice for a low budget, am I right?

I also saw on certain threads that I might have to modify something to make it fit. I'm a real noob in mechanic so I won't be able to do anything hard.
Is it necessary tto put a plate of wood like this under :



And isn't it dangerous? Is the heat bag necessary?


Thank you very much for your help!


I also saw that odyssey propose the pc1200mjt for 2005 rx-8 manual transmission, but is it really better for an everyday car? (not for tracking)

Thanks!

 

its funny that you guys trying to save that 20 lbs for a god damn street car but then you have to worry this and that and you even know that those battery does NOT even have enough juice to power the car.

and the pc1200mjt does not even saves any weight, and its weaker than a good lead acid battery. sad.