ColorChange

Anyone want to lose 30 relatively high cg pounds and relocate the remaining wieght down low? What's missing?




It is easy to replace the battery in our cars with an Odyssey battery. The stock weighs 46.8 lbs, and the Odyssey 680 weighs 14.6 lbs for only $85. You will need a charger if you are going to run this often.



I only have it temporarily mounted and plan to try high performance velcro to hold it down. It's dry cell so no concerns of leaking.

Here is a link for more batter info.

http://www.odysseybatteries.com/battery/pc680.htm

Rich Sandor

ColorChange: Do you know why the factory put the battery where they did?

Batteries need to vent gases into the air. I'm sure Optima batteries are no different. With your setup, the battery is sealed in the boot compartment, where all the gasses will build up, and could potentially be ignited by electricity from your audio equipment.

penguinking

he said it was a dry cell...

ColorChange

Rich: The two batterie are extremely different. Did you notice the Odyssey was laying on it's side? No venting, no acid, no gases.

Greg Fishman

CC,
You need to put a plastic cover of some sort over the positive terminal.

Rich Sandor

Dry cell just means that the acid is suspended inside a fibreglass type matting, instead of free flowing. Thus it will not leak or spill if tipped over. However, the battery still generates hydrogen gas like any other battery. If you read the manual it says the Optima comes with a "venting valve" which obviously indicates it DOES generate gases. You do not want to have your sealed boot compartment filled with HYDROGEN gases. (remember the Hindenburg?)

Z-man

My only concern is the fact that you have a twisted over tie-down holding that thing down.

If that thing gets loose, you'll have something that looks like an 'under the trunk' hailstorm occurred in your boot! That setup would never pass my tech line if you were going to track that bad boy.

Besides that, shaving off a mere 30lbs on a ~3400 lb car isn't that great a savings. Swap out the seats for a set of lightweight racing buckets, and you're better off.

Or just get a 911SC or 964 and go crazy!

-Z-man.

FormulaOne10

Hydrogen is so incredibly small and light that I would not worry about it getting trapped in a compartment made only to keep out moisture. Hydrogen is amazingly hard to confine without proper seals (or using a balloon, etc)...especially in any significant quantity.

Also...I do think that with a safer mounting system this would be a very nice modification. I've used the PC680 odyessy on my other 944 (made a solid mounting system that passed through tech multiple times) and it shaved ~25lbs off while lowering the CG about 7 inches. Very nice inexpensive upgrade(~$100 at BatteyMart.com).

kurt M

Not to pile on but this would not pass a Potomac tech line as well. Velcro is not recomended as the bat needs to be hard mounted to pass a tech. In an impact the G forces could pull it loose and after banging around some might short out and start a fire. There is no fuze on the pos wire and a shorted bat or pos bat wire is something you do not want to see in your trunk!
The extended pos wire crimps the trunk seal and will keep it from sealing the top of the trunk. While that might let water and dust in it just might keep the hindinburg ending at bay. You might be able to put a hose from the bat vent to outside.

Does the bat have the same charge ansd discharge values as the stock unit? If not and they are too far out of spec it might make the alt and reg work too hard and fry something $ and you have a lot of $ elec stuff in that car. The bat acts as a buffer as well as energy storage.

A little more fine tuning on the mount and wire and you can safely save some high COG weight.

Z-man

It isn't just the G-forces in a collision that would dislodge a battery held down by 'high performance velco' it's cornering speeds as well.

And all that puppy needs to do is rotate a quarter turn counter-clockwise, and if the two battery terminals happen to hit that metal plate holding your amp/cd whatever (?) in place, it's "POOF" you've got a FIRE.

A friend of mine was using an Odessey battery (IIRC) in his early 911, and even though it was sercurely mounted, it did get loose and contact was made and a fire started. As he put it, "Fortunately, the fire was contained in an area just over the gas tank." (Good thing he had a FE handy and a good sense of humor!)

The correct / original mounting point for batteries in Porsches (and all cars for that matter) were designed to keep the potential for danger at a minimum. Messing around with that design can introduce more problems than improvements.

Why not just mount the Odessy battery in the original battery location? Your cg will improve a little due to the weight savings, but not as much as if it battery were lower. How much is lowering 30 lbs an additional 6 inches going to really effect your cg, especially on such a heavy 3400lb car?

Too many compromises for too little gain, IMHO.
-Z-man.

Rich Sandor

Is that why the positive terminal on 944 batteries is less than an inch away from the protruding metal windshield frame on the chassis? Not every factory solution is the best one.

However I agree that moving the battery will lead to compromises being made, and for CC's application, I think the factory already made the best compromises.

I think upgrading to a lightweight dry cell battery and keeping it in the stock location is probably the best solution until you decide to turn your car into a full on race car.

ColorChange

Rich: I don't think there is any chance of creating enough hydrogen from this battery to reach an explosive concentration (4% minimum). The bonnet is anything but tightly sealed and this battery will generate very little hydrogen (otherwise you would need to add water/acid ... right?).

But, I think I agree with the others (thanks) to just leave it where the battery was. Moving 15 lbs just isn't worth it.

Glen

FYI, factory mount area in 996 was to maximize trunk space. In Grand Am Cup cars the battery is hard mounted very close to where Tim has his.

aeshultz

Glen is correct- I've crewed for Cup Car teams and helped them relocate the battery between sessions (I think it was an early '00 or '01 car). Unfortunately, all they had was the standard "wet" battery - the trunk paint was a little messy after 2 days with Mid-Ohio throwing acid out.