Battery?

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85306Fox
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Battery?

Postby 85306Fox » Sat Feb 22, 2014 11:08 am

I am in the process of completing the electrical system in my SN95 and have a question regarding batteries...

The rule regarding batteries states:

7.9.7 The battery may be relocated. The battery must be of the same type, group size (i.e. 24F), and
voltage as originally equipped, or heavier, and may not be modified.

My question is in regards to the language "or heavier"... SN95's originally came with Group 58 batteries. Does "or heavier" mean I can use a different Group size as long as it weighs more than a Group 58 battery?

I am not trying to find a "loophole" to aid in balancing the car with a truck battery. I would just like to use an AGM battery to avoid having to use a battery box and I have been unable to find a Group 58 AGM battery.

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Postby Glenn » Sat Feb 22, 2014 2:49 pm

What does the rule say about battery boxes with regards to an AGM battery?
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Postby Glenn » Sat Feb 22, 2014 2:56 pm

Never mind. AGM battery types were added to the list of those not needing a box.
FYI - AGM's are still a lead acid battery. The liquid is absorbed into fiberglass mats rolled up in the case rather than liquid electrolyte tanks w/ lead plates.

The or heavier will allow for a larger than stock battery. But if I see a non-passenger car sized battery installed, I'm waiving the BS flag and requesting it be replaced. I will not allow massively large batteries in CMC.
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85306Fox
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Postby 85306Fox » Sat Feb 22, 2014 3:11 pm

Thanks for the clarification Glenn.

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Postby MHISSTC » Sun Feb 23, 2014 6:09 am

Although some individuals may be familiar with what OEM group sizes came in some cars, I am unaware of anyone actually keeping a master list of every OEM battery group size for every vehicle allowed in this series.

The bottom line is if you show up with a battery that looks like a "reasonably sized" passenger car battery, no one will think twice. If you show up with a battery that looks like it came from a large diesel generator or a garden tractor, you're going to be asked to change it.
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Postby cozog » Wed Feb 26, 2014 11:52 am

Not that I'm telling you how to build your car, but consider the extra safety of a battery box. If you slam a wall a$$ end first, it could get free and fly around the cabin or get punctured and spray acid around. Just saying...
Todd Johnston, #59

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Postby 85306Fox » Wed Feb 26, 2014 2:13 pm

cozog wrote:Not that I'm telling you how to build your car, but consider the extra safety of a battery box. If you slam a wall a$$ end first, it could get free and fly around the cabin or get punctured and spray acid around. Just saying...


Todd, after doing some more research on AGM batteries I did in fact reconsider the battery box and will be putting the battery in one... Now I just have to fabricate a tray for the box to sit on as the location I want to mount it is an odd shape.

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Postby D. Francis » Thu Feb 27, 2014 2:12 pm

85306Fox wrote:Now I just have to fabricate a tray for the box to sit on as the location I want to mount it is an odd shape.
Just be reasonable with the tray construction so nobody claims it's ballast.
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Postby 85306Fox » Thu Feb 27, 2014 7:25 pm

D. Francis wrote:
85306Fox wrote:Now I just have to fabricate a tray for the box to sit on as the location I want to mount it is an odd shape.
Just be reasonable with the tray construction so nobody claims it's ballast.


Thanks David... It is just a very simple structure to raise the battery ~1 1/2" off the floor and probably weighs less than three pounds total. The spot were I am mounting the battery is not flat so I had to fabricate the tray.

Sort of on the topic of batteries... You all that have relocated your battery are you using a remote solenoid?

I had originally planned out my wiring diagram with the 2 gauge cable going directly to the starter then the push button to the solenoid on the starter. This is the way I had always done it on my drag cars... Looking at the cable the other day it just dawned on me that the 2 gauge cable will always be "hot" and there is no way to fuse that circuit due to the amperage pull of the starter. Now I am going back and re-doing my starting circuit so the constant "hot" cable is minimized. Seems like every time I go forward there is one step backwards and I am doing something over...

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Postby Supercharged111 » Fri Feb 28, 2014 7:16 am

I've seen 200A breakers before, but I know my car's not set up that way. Is 200A not enough? Too much? I'm thinking of 2 way flow here. On one hand, you want enough in case the car turns into a pig and won't start, but on the other hand if the alternator won't put out enough to blow a 200A breaker, will it?
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cozog
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Postby cozog » Fri Feb 28, 2014 11:36 am

85306Fox wrote:I had originally planned out my wiring diagram with the 2 gauge cable going directly to the starter then the push button to the solenoid on the starter. This is the way I had always done it on my drag cars... Looking at the cable the other day it just dawned on me that the 2 gauge cable will always be "hot" and there is no way to fuse that circuit due to the amperage pull of the starter. Now I am going back and re-doing my starting circuit so the constant "hot" cable is minimized. Seems like every time I go forward there is one step backwards and I am doing something over...


My 4th gen has a factory fusable link between batt and starter. Is that an option for you?
As long as the solenoid is run through the master switch and ca be cut off, does it matter if the starter is always hot?
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Postby 85306Fox » Fri Feb 28, 2014 3:11 pm

Supercharged... I have done some research on fuses for the 2 gauge cable as well as circuit breakers. The general consensus is that if a fuse or breaker is large enough to keep from blowing or tripping under the amperage draw of the starter then it is too big to protect the cable.

Todd... I thought about the fact that it may not matter that the cable is always hot if I can cut it off by the master switch. I know the probability is low but with my luck I would be involved in a crash and rendered unconscious then die a fiery death.

I realize that we can't cover every possible situation but I just want to build the car as safe as I can...

One fella that I spoke with regarding this situation suggested using the remote solenoid to activate a relay which would then activate the solenoid on the starter. That may be the route I end up taking but I am just exploring the "simplest" ways of doing this first...

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Postby Supercharged111 » Sat Mar 01, 2014 8:59 am

One thing that's on my mind with using a solenoid in the back is that your fuel trims get "forgotten". IAC does too, but less of a concern to me. Even though these are race cars, they still learn with their stock engines and stock computers and the mere act of cycling the master cutoff switch can affect your annual dyno reading vs. letting it run with its LTFTs in place. I've been toying with the idea of installing a wideband to see how significant this is, because I also don't like the thought of all that live wire just sitting there waiting for me to throw a breaker bar on it after a race weekend and create a fireworks show and inevitably destroy something I'd rather not replace. Master cutoff won't save you there, so now I'm thinking thoughts of a 100ish amp breaker, something that will blow before the cable and then maybe a bypass that runs in parallel and uses that aforementioned starter solenoid to come online? You could merge them together inside the battery box and still only have one cable running to the front. Damn I'm good. :lol:
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Postby 85306Fox » Sat Mar 01, 2014 11:12 am

Supercharged111 wrote:One thing that's on my mind with using a solenoid in the back is that your fuel trims get "forgotten". IAC does too, but less of a concern to me. Even though these are race cars, they still learn with their stock engines and stock computers and the mere act of cycling the master cutoff switch can affect your annual dyno reading vs. letting it run with its LTFTs in place. I've been toying with the idea of installing a wideband to see how significant this is, because I also don't like the thought of all that live wire just sitting there waiting for me to throw a breaker bar on it after a race weekend and create a fireworks show and inevitably destroy something I'd rather not replace. Master cutoff won't save you there, so now I'm thinking thoughts of a 100ish amp breaker, something that will blow before the cable and then maybe a bypass that runs in parallel and uses that aforementioned starter solenoid to come online? You could merge them together inside the battery box and still only have one cable running to the front. Damn I'm good. :lol:


Supercharged... You lost me on the fuel injection stuff, I am not that smart... LOL!!! My car is carbed so I don't have to worry about a computer. But I do understand about what you are saying regarding the computer to have to "relearn" everything once all power is shut off. I did speak with a fella this morning about installing a breaker or a fuse. He suggested a 200 amp fuse. His thinking was the breaker may be too unreliable and it would become a pain to always have to re-set it to crank the car. I guess if it were placed within reach while you were strapped in the car it would be Ok.

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Postby Supercharged111 » Sat Mar 01, 2014 12:14 pm

If it did blow mid-race, you'd still run on alternator. Maybe one could get creative with an LED that illuminates when the thing pops. Even if it did pop mid race and you stalled, the solenoid would still allow the car to start. I'm really selling myself on this idea now. Better yet, you could install a bypass switch for the solenoid that would energize it in the event of the breaker popping. At that point, you'd lose the function of the breaker, but the battery would still take a charge from the alternator. You could even make that bypass an automatic function.
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