I posted this over on the Hybrid forums, but double exposure never hurts:

Hey all,

I did not find much searching so here is my question:

I am going to switch to an Optima dry cell and I would like to mount it in the rear. I am looking for suggestions on how to mount it securely and where. I am thinking either up against the metal lip right behind the seats or in the spare tire well. My reasoning for the first location is to reduce rotational inertia in the horizontal plane. The second is kind of the standard location and increases rear wheel traction and lowers the COG of the car. Ideally I would like to keep the spare, which is obviously not possible if I place it in the spare tire well.

If anyone has pictures of their setup that would be perfect.

Thanks

Ryan

Sorry I cannot help you with battery relocation, How ever I can tell you how pleased I am with that optima dry cell in my '72Z! I will NEVER buy another wet one again! I re-installed it in the stock location with great results! Bob.

Yes, Optimas are wonderful. Ive been running one in my Supra for about a year now. Ive heard stories of them lasting 7 years+

Not really a bad idea, never actually heard of any zed owners actually doing this as the weight ratios/COG are pretty good as they are.

My thoughts would be to place the pack behing the pax seat/tool storage area somehow [RHD drive].

If you're using this space for extinguiser storage then I have no idea where else you could relocate the battery?

Yeah, but pretty good is exactly that. Pretty good. Better is always, well...better :classic: Every little bit counts, right?

Good idea as far as putting it in the tool box, I assume that is supposed to be behind one of the seats? Looks like there is a tab for something to mount there. My car obviously has nothing there :cross-eye

Right now I am leaning towards behind the passenger seat *LHD car* as close to the transmission tunnel as possible. That way I can keep the spare and it also puts the battery extremely close to the COM of the car.

Thanks for the ideas

Ryan

You hadn't mentioned a specific model. I assumed it was a 240?

Not being familar with this type of battery, is there much appreciable difference in weight?

Your right! hehe.

Yes it is a 240.

Difference in weight between a standard lead-acid battery and an Optima sealed battery? Hrm. Using the power of my perfectly calibrated memory functioning off my perfectly calibrated hand-scales I would say the Optima is a tad bit lighter than a standard battery. One thing to note is the Optima is quite a bit smaller in dimension, and that is the full size version. They have quite a product line, which includes several smaller dimensioned batteries.

Ryan

Wonderful, do I win a cigar?

You may need to consider other issues here as well, as the springs vary in HLS-30's. THis was a factory design to make up for the weight of the driver.

Obviously this isn't a problem in HS-30's and the reason for me querying whether you would notice any appreciable difference by moving the batt to the COM.

Other factors to consider would be the appreciable weight gain that you will introduce to the vehicle by the addition of longer heavy cabling?

No cigar right now , but I can get you a cuban if I head down to mexico :beard:

Several good points again, thank you.

Springs: I will be switching to coil-overs very soon with no consideration of driver's weight. This means that placing the battery opposite of that weight will be a good thing :classic:

Weight gain: Well between the cabling and any additional mounting hardware that may be required I could see a gain of maybe 5 lbs top. A good portion of this gain would be in the new, longer cables. This is okay thought because these cables will be run along the Z (heh) axis of the car.

That is with the x axis running off to the left and right of the driver, the y axis being vertical and the z axis running front to rear.

By running these cables along the center line of the car (z axis) it takes out a whole chunk of the COM, COG, and torque equations.

After all that blabber it basicaly means it won't add up enough to undo the substantial loss in rotational inertia by moving the considerable mass of the battery closer to the origen. That is the crossing of x,y, and z axes, IE the COM of the car. Right between the seats more or less.

Thanks again, keep those thoughts coming.

Ryan

One mounting suggestion would be go to your local boat center.They have plastic enclosures for the batterys.I would secure it by a seatbelt type strap that was anchored to the car.Justa thought.

Great, thanks. Ill look into it. I was going to go by one anyways to get the cables.

Ryan

Okay just got off of the phone with Optima. I asked what they recommend when mounting one of their batteries inside a vehicle.

"With any battery it is necessary to provide vent tubes and some kind of sealed container, however Optima batteries will not begin to vent or discharge unless overcharged"

So in effect he said officially yes, but you don't really need to.

I think I will try to find a sealed container (possibly from a boating store) but if nothing turns out to be convenient I will just mount it open.

Ryan