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Lightweight battery relocation?

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Old 04-19-2017, 07:34 AM
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Default Lightweight battery relocation?

The short of it is, I want to use a lightweight battery but didn't want to relocate it to the rear because of losing juice with the long cables. Because of my stand alone sitting in the stock battery location it must be moved anyhow so I was going to build a box where the stock radiator overflow is, under the stock battery location.

According to NHRA rules if the battery is moved from the factory location there must be a cut off switch (they would probably want one even if it wasn't moved). Most of these go on the rear of the car. Well if I do that then I'm back to the long cables. I really don't want the cut off switch located anywhere else for aesthetic reasons and the fact that in case of trouble 9 out of 10 people will go to the back to shut off power because that's where everyone puts their switches.

So, guys that have relocated lightweight batteries what are you doing with them? Would a lightweight battery be fine in the back? The car is 90% race but it will be driven on the street some. I don't have a stereo or and hvac but still have power windows and lights. Plus nitrous, electric fan and whatnot.
Old 04-19-2017, 08:57 AM
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It's required to be in the back. They will check to make sure that the switch kills all electrical power to the vehicle when actuated.

Run #4 cable up to the front and ground the battery to the cage.

Also, don't forget.. it needs partitioning/bulkhead or firewall for legality.
Old 04-19-2017, 09:28 AM
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Originally Posted by a05c
It's required to be in the back. They will check to make sure that the switch kills all electrical power to the vehicle when actuated.

Run #4 cable up to the front and ground the battery to the cage.

Also, don't forget.. it needs partitioning/bulkhead or firewall for legality.
You're saying the switch is required to be in the back not the battery right? Ok no problem. And the factory firewall should be fine as long as the battery stays under the hood I'm guessing. My major question is, with all of that wire will a lightweight battery have enough juice for me?
Old 04-19-2017, 09:33 AM
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If the battery is back there, then the switch has to be back there.
Old 04-19-2017, 09:38 AM
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Originally Posted by a05c
If the battery is back there, then the switch has to be back there.
My post is about wanting to keep the battery in the front...
Old 04-26-2017, 11:39 AM
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I don't have the NHRA book in fron t of me, but it makes complete sense to me that the switch needs to be in the back. The whole purpose of it, is so if your car flips, the person running up to the car, knows the switch is in the back, it must be labeled properly, and then can kill power to the car very quickly. With that being said, since the switch has to be in the back, if you had the battery in the front, then you would have to run your power cable all the way to the back, and then all the way back up front. So it's better for the battery to be in the back in the first place.
Old 04-26-2017, 11:54 AM
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Ya I'm pretty sure I read it needs to be in the back in a visible location blah blah blah. I think I'm just putting the battery back there too.
Old 04-26-2017, 11:56 AM
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Originally Posted by 93camaro_zzz
I don't have the NHRA book in fron t of me, but it makes complete sense to me that the switch needs to be in the back. The whole purpose of it, is so if your car flips, the person running up to the car, knows the switch is in the back, it must be labeled properly, and then can kill power to the car very quickly. With that being said, since the switch has to be in the back, if you had the battery in the front, then you would have to run your power cable all the way to the back, and then all the way back up front. So it's better for the battery to be in the back in the first place.
Will a lightweight battery cause problems with starting or other electrical issues being in the back?
Old 04-26-2017, 12:25 PM
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I was in the same situation. Wanted front battery but nhra rules say faster than 9.99 and you have to have a switch. I didn't want to run cables front to back for the starter, so I simply just ran the normal wire to the starter and normal ground wire to the block, but then ran a 4ga front to back that actually powers the car as if the battery was back there

I'll go one step farther soon and install a 250amp fuse on the starter cable in case it gets pinched in an accident

Zero starting issues and car dies when the switch it turned off

To do it correctly, you need to run a positive and negative cable from the rear mounted battery, so there isn't any extra wiring running two positive 4ga wires


Maybe call the local nhra office and ask. If it's still up front and within the frame rails it might be fine until you reach 9.99
Old 04-27-2017, 12:35 PM
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Originally Posted by 85Iroc
Will a lightweight battery cause problems with starting or other electrical issues being in the back?
I will let others comment on this. I still have a normal car lead acid battery (heavy). My buddy bought and ran one of those lightweight batteries, and admittedly sometimes it was hard to start the car, if he left his trans fan on between rounds, or whatnot.
Old 04-27-2017, 01:02 PM
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Originally Posted by Nathaninwa
I was in the same situation. Wanted front battery but nhra rules say faster than 9.99 and you have to have a switch. I didn't want to run cables front to back for the starter, so I simply just ran the normal wire to the starter and normal ground wire to the block, but then ran a 4ga front to back that actually powers the car as if the battery was back there

I'll go one step farther soon and install a 250amp fuse on the starter cable in case it gets pinched in an accident

Zero starting issues and car dies when the switch it turned off

To do it correctly, you need to run a positive and negative cable from the rear mounted battery, so there isn't any extra wiring running two positive 4ga wires


Maybe call the local nhra office and ask. If it's still up front and within the frame rails it might be fine until you reach 9.99
I think I'm just going to start with a smaller (Honda or similar) battery in the back as I should be well south of 9.99.

Originally Posted by 93camaro_zzz
I will let others comment on this. I still have a normal car lead acid battery (heavy). My buddy bought and ran one of those lightweight batteries, and admittedly sometimes it was hard to start the car, if he left his trans fan on between rounds, or whatnot.
Ya I don't want any issues like that-
Old 04-27-2017, 03:39 PM
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That's why I left my small battery up front. And if your like me, we'll south or 9.99, the added weight up front can help keep the front tires on the ground Light weight cars can benefit from well placed weight



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