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Moving the battery to the rear


Guest rkroel

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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

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Hah! Thats a beautiful install Dan. But yes, a little more involved that what I am looking to do but a very good solution. :wink:

 

What did you use for the wiring? Someone suggested using sealed battery cabling availible from boating stores.

 

Thanks,

Ryan

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Guest 81na ZX

Optima battery as in Red top or Yellow top? Thoes are Gel Cells not Dry Cells and according to the people I've talked to, you still need a sealed box for them. If you wanted to go really dry cell, look at Odyssey batteries. My Talon has one that would fit behind or under the seats in my ZX...

 

My 2 suggestions would be based on your need:

1) for rear end traction, as far back as you can mount it.

2) for lowering COG, if you can do it, adjacent to the driveshaft tunnel between the seats.

 

As a continuation of #2, if you have access to corner scales, you could get it perfect ;)

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Yes I would use a Red top starter battery. The Yellow top batteries are deep cycle and the Blue top batteries are for marine applications. I had dry cell stuck in my head from reading a previous post, thanks for pointing that out. They are lead-acid batteries so they do indeed use gel cells. However they are a completely sealed design. Meaning you can mount them at any attitude without worry of any leakage. In fact on the batteries themselves are labeled "Non-spillable".

 

As far as crashes go I would still doubt any spillage would occur. If a crash produced enough energy to rip something so dense open the occupants would surly be long dead anyways. If I am making a stupid assumption feel free to tell me. :twak:

 

I have seen numerous occasions with them mounted without sealed battery boxes. Although it is not wise to make a decision based on what others do.

 

Can someone with experience provide an opinion?

 

Thanks for the help.

 

Ryan

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Guest Nic-Rebel450CA

I have a sealed spillproof battery mounted behind my passenger seat right behind that little lip you are referring to. I will take some pictures when I get home from work and throw them up online really quick. I cant offer any installation info other than by observation of the setup as I was not the one that installed it there.

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Isn't there another danger besides the battery getting torn open and spilling acid? Like the explosive hydrogen that they release when charging???

 

Not sure exactly how dangerous that is, but I wouldn't exactly feel comfortable smoking in my Z while sitting on the battery...

 

Jon

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jon...

i thought about that too, then when i remembered that i was putting a fuel cell in the hatch i decided i'm just getting rid of the ashtray altogether. more excuses to stop and smoke so i can show off the car (when it's done :cuss: )CAN'T be a bad thing...

 

so how did you guys who moved the batteries run the wires? i have been thinking about doing this myself... if only because it makes the engine bay look cleaner. anything else will be a bonus since i don't plan on much racing, at least not enough to really be concerned about it.

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Well I don't smoke, and I shoot anyone who attempts to smoke in my car. So that shouldn't be a problem :-D The Optima's are designed around a completely sealed system. Nothing in nothing out. That being said I think I will give Optima a call and see what they say about it.

 

Thanks again

 

Ryan

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It's not so much the smoking, it is the highly explosive hydrogen gas that worries me. Static electricity would pose a risk if the concentration of hydrogen got high enough. Plus it is noxious. I don't know how it could charge and not release hydrogen. Maybe it can???

 

Again, I don't know if it would be a risk or not, but I'd rather have the battery in a sealed compartment in any case.

 

Same with the fuel cell.

 

Jon

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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. :wink:

 

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

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Guest 81na ZX
It's not so much the smoking' date=' it is the highly explosive hydrogen gas that worries me. Static electricity would pose a risk if the concentration of hydrogen got high enough. Plus it is noxious. I don't know how it could charge and not release hydrogen. Maybe it can???

 

Again, I don't know if it would be a risk or not, but I'd rather have the battery in a sealed compartment in any case.

 

Same with the fuel cell.

 

Jon[/quote']

 

Correct, this is the reasoning behind the sealed container, per NHRA rules. As the Optima rep said, they will vent H2. On a hot day, an average battery in a closed car will suffocate a person. An Optima will only do it if they are overcharged, but still can.

 

The H2 is a by product of the energy creation/storeing within a lead acid battery. A gel cell is still a lead acid, but the acid is trapped in a gel - thus its unspillable. A traditional battery is a flooded batery, the acid is "loose".

 

The nature of dry cells dictate that it will not, under any circumstances, leak H2. As dry cells do not have lead acid in them, thus the creation/storing of energy doesn't create H2.

 

As for sealing, it depends on what racing body's rules you want to meet. NHRA rules say that the box HAS to be NHRA-Approved. The only one I know off hand is the Morosso box @ $100... For you car to pass tech at a good NHRA track, a boat-spec box won't do ;)

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Bah! There you go and ruin my attempt at being ignorant! Heheh. $100 morosso box? :x Ill pass. I don't plan on needing to meet NHRA rules anytime soon anyways. Thanks for the very informative post.

 

Decisions decisions..

Ryan

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Errr, I just went out and looked at my '73 parts car and it has the two storage spaces with the doors on top. I don't think my '71 has them, ill check when I get home.

 

Hrmm

 

Ryan

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In my '79 ZX, I used the Mad Enterprises' http://www.madelectrical.com/catalog/tm-1.shtml trunk mounted battery kit to run 1/0 cable to an Optima battery and starter solenoid located behind the passenger seat where the storage compartment was located. I cut away a small amount of the sheet metal forming the storage compartment and made a mount so the battery sits flat. I then fashioned a metal hold down strap that is bolted through the body. Lastly, I used a cardboard box as a plug to make a fiberglass box for the battery with a lid that sits down over the box. It is not airtight and it is not vented. I didn't want to buy a commercially made battery box since all the ones I saw were much bigger than necessary. It turned out fairly nicely although, like most projects, I'd make a few changes if I had to do it over again. I ran the 1/0 cable through the firewall using a substantial grommet. I used the kit from Mad because I had seen a lot of articles by Mark Hamilton (owner) in car magazines. I just got my mig welder set up this weekend and I'd still like to add a little sheet metal to the box area to really finish it off. However, I need to develop a little more skill with the welder before I do so. I will remove my computer and the battery from the car before doing any welding on it. I'm sorry I don't have a camera, scanner or web site yet since I know a few photos would help explain what I did. The engine compartment looks much less crowded with the battery removed although with power steering, power brakes and air conditioning, it's still pretty full. :-D

John

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Since my Z is not a daily driver, I thought I would replace my big, heavy lead acid battery with one from a garden tractor or motorcycle. I know a guy who has done it, drives his car same as mine - in warm weather, not everyday, light use. And no relocation needed.

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