Topic: Battery relocation
What gauge cable should be used for relocating a battery to the rear of a car?
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What gauge cable should be used for relocating a battery to the rear of a car?
I've pulled complete cables from BMWs and M-Bs at my local U-Pull-It;I didn't look at the gauge. I think one was $5 back then. Can't beat it.
Give or take, 30% larger cross section than when it was in the front...unless it is 1972'ish El Darado.
Better to go larger than smaller. Larger cable won't hurt anything, but smaller definitely can. Personally I'd use 2 gauge at a minimum if it's a more modern car. Bigger if you can.
Junkyards can turn up stuff to pull but I personally prefer just buying stuff meant to be used as welding cable. It's usually more flexible, which makes installing it cleanly really easy. You should only need a long length for the positive side since that side has to run to your kill switch and then engine bay. The negative you can just run a short piece to a good solid ground location nearby the battery. We weld a tab to the cage and run a short length to that. As long as you have good grounds from your engine to chassis you shouldn't have any problems with that setup.
Better to go larger than smaller. Larger cable won't hurt anything, but smaller definitely can. Personally I'd use 2 gauge at a minimum if it's a more modern car. Bigger if you can.
Junkyards can turn up stuff to pull but I personally prefer just buying stuff meant to be used as welding cable. It's usually more flexible, which makes installing it cleanly really easy.
Normally I would agree with you as I think three off our racecars use retired welding leads (OSHA regs do noy allow repairs on them so on flaw in a 50' 00 cableand you get it for copper price) but just did the E46 positive cable into the the Dustbuster...that is some super flexible quality wire...as good or better than welding leads just a bit smaller (40 MM).
TheEngineer wrote:Better to go larger than smaller. Larger cable won't hurt anything, but smaller definitely can. Personally I'd use 2 gauge at a minimum if it's a more modern car. Bigger if you can.
Junkyards can turn up stuff to pull but I personally prefer just buying stuff meant to be used as welding cable. It's usually more flexible, which makes installing it cleanly really easy.
Normally I would agree with you as I think three off our racecars use retired welding leads (OSHA regs do noy allow repairs on them so on flaw in a 50' 00 cableand you get it for copper price) but just did the E46 positive cable into the the Dustbuster...that is some super flexible quality wire...as good or better than welding leads just a bit smaller (40 MM).
I'm happy to be wrong about the junkyard stuff. My own experience is more that the jacketing gets more and more stiff with age, so you just have to look out for that. But E46 stuff shouldn't be old enough for that, you're right.
I mostly meant I personally prefer just buying newer known condition cable. Nothing against the junkyard option.
Buy a light weight battery and avoid the weight penalty of the cable and battery in the trunk. It makes no sense to do this or worry about this and costs more than my solution.
Buy a light weight battery and avoid the weight penalty of the cable and battery in the trunk. It makes no sense to do this or worry about this and costs more than my solution.
There are reasons to do it other than weight. It can make working in the engine bay a TON easier in some cars. That's why we moved it in the saab, the engine bay was so tight that anything we could remove helped. Moving the battery opened up a giant corner of the engine bay. Couldn't care less about the weight shift, it was a quality of life change.
I do disagree with the cost statement though. Cost me less than $75 to get the cable and battery box I needed, which is a lot less than a fancy lightweight battery.
As with most things YMMV.
There are reasons to do it other than weight. It can make working in the engine bay a TON easier in some cars. That's why we moved it in the saab...
This is also why I relocated the battery in my '67 96. I moved it into the space formerly occupied by the rear seat and repurposed one of the seat attachment points for the ground cable.
A lightweight battery may decrease the front-end weight, but it does nothing to counterbalance it.
Yes your front/rear percentages will improve, but they would be noticeably improved by shifting
that weight to the trunk. Recent MT article with scales and a lightweight battery.
I use 4ga, seem to work ok with Anderson SB50 connectors. On V6 Probe and Maxima.
A lightweight battery may decrease the front-end weight, but it does nothing to counterbalance it.
Yes your front/rear percentages will improve, but they would be noticeably improved by shifting
that weight to the trunk. Recent MT article with scales and a lightweight battery.
Why would you choose moving weight vs getting rid of it?
40lbs off the front is better than moving 50lbs to the rear.
Taking 40 lbs off the front also improves your weight distribution.
DelinquentRacer wrote:A lightweight battery may decrease the front-end weight, but it does nothing to counterbalance it.
Yes your front/rear percentages will improve, but they would be noticeably improved by shifting
that weight to the trunk. Recent MT article with scales and a lightweight battery.Why would you choose moving weight vs getting rid of it?
I had a reply that probably would have been interpreted as me being a Condescending Smart Ass.
Instead:
There are many answers to your questions, and just as many opinions on those answers.
There are no "One Size Fits All" solutions.
Maybe for this car build it would be detrimental to have the extra 25lbs on the chassis and a lightweight battery makes sense.
Maybe this car will be used in a race series where am Optima battery is required, so lightweight batteries are not an option.
I dunno.
I do know that where weight is in the car has a greater effect on handling than how much weight there is (within reason, of course.)
The extra weight, if placed in the perfect location so as to have no effect on handling, would make the car accelerate slower,
use more fuel to keep it rolling, and make braking take more distance.
BUT, if you put that weight in the perfect spot to have the greatest positive effect on your handling, your tires will be happier,
your lap times may drop, and the birds will sing so sweetly you may tear up. Jay still won't fart rainbows, though.
If I had the time, and disposable income, I would test your theory against mine. Sadly, I cannot do this on a teacher's salary.
BTW, none of this was written with the intent of being a smart ass.
(Except the part about Jay. He may fart rainbows for all I know. And, possibly the part about the birds. I doubt they care all that much. I dunno.)
Though, some may interpret the above statement as the exact opposite of the truth. (Except for the part about Jay) YMMV
Edited for fat finger mistakes. And possibly for clarity. Definitely not for smart assery
squidrope wrote:Buy a light weight battery and avoid the weight penalty of the cable and battery in the trunk. It makes no sense to do this or worry about this and costs more than my solution.
There are reasons to do it other than weight. It can make working in the engine bay a TON easier in some cars. That's why we moved it in the saab, the engine bay was so tight that anything we could remove helped. Moving the battery opened up a giant corner of the engine bay. Couldn't care less about the weight shift, it was a quality of life change.
I do disagree with the cost statement though. Cost me less than $75 to get the cable and battery box I needed, which is a lot less than a fancy lightweight battery.
As with most things YMMV.
And what would a new battery add to that cost? Most of these heaps need a new battery as well (mine did). You spent years driving a car that broke. I'm of a different mindset. Cheers! Make it light and simple=better/"fancier" in my opinion.
hkerekes wrote:DelinquentRacer wrote:A lightweight battery may decrease the front-end weight, but it does nothing to counterbalance it.
Yes your front/rear percentages will improve, but they would be noticeably improved by shifting
that weight to the trunk. Recent MT article with scales and a lightweight battery.Why would you choose moving weight vs getting rid of it?
I had a reply that probably would have been interpreted as me being a Condescending Smart Ass.
Instead:
There are many answers to your questions, and just as many opinions on those answers.
There are no "One Size Fits All" solutions.
Maybe for this car build it would be detrimental to have the extra 25lbs on the chassis and a lightweight battery makes sense.
Maybe this car will be used in a race series where am Optima battery is required, so lightweight batteries are not an option.I dunno.
I do know that where weight is in the car has a greater effect on handling than how much weight there is (within reason, of course.)
The extra weight, if placed in the perfect location so as to have no effect on handling, would make the car accelerate slower,
use more fuel to keep it rolling, and make braking take more distance.BUT, if you put that weight in the perfect spot to have the greatest positive effect on your handling, your tires will be happier,
your lap times may drop, and the birds will sing so sweetly you may tear up. Jay still won't fart rainbows, though.If I had the time, and disposable income, I would test your theory against mine. Sadly, I cannot do this on a teacher's salary.
BTW, none of this was written with the intent of being a smart ass.
(Except the part about Jay. He may fart rainbows for all I know. And, possibly the part about the birds. I doubt they care all that much. I dunno.)
Though, some may interpret the above statement as the exact opposite of the truth. (Except for the part about Jay) YMMVEdited for fat finger mistakes. And possibly for clarity. Definitely not for smart assery
Weight always has an effect on handling. Ask any competitive road racer if they want to move 50 lbs or remove 50 lbs. The answer is always remove the weight. You can always move weight around if you need to ( fuel cell, fire suppression, trans coolers, cool suit cooler), you cant always remove weight.
Our battery is 7.8 lbs and sits in the passenger foot well. The factory battery was 50 lbs and sat on the front right corner. Upgrading to 2 gauge wiring and a battery box, still lost us 40 lbs.
TheEngineer wrote:squidrope wrote:Buy a light weight battery and avoid the weight penalty of the cable and battery in the trunk. It makes no sense to do this or worry about this and costs more than my solution.
There are reasons to do it other than weight. It can make working in the engine bay a TON easier in some cars. That's why we moved it in the saab, the engine bay was so tight that anything we could remove helped. Moving the battery opened up a giant corner of the engine bay. Couldn't care less about the weight shift, it was a quality of life change.
I do disagree with the cost statement though. Cost me less than $75 to get the cable and battery box I needed, which is a lot less than a fancy lightweight battery.
As with most things YMMV.
And what would a new battery add to that cost? Most of these heaps need a new battery as well (mine did). You spent years driving a car that broke. I'm of a different mindset. Cheers! Make it light and simple=better/"fancier" in my opinion.
Just to be clear, I wasn't saying that you shouldn't have gone the lightweight route. I was only offering that there are reasons other than weight to move a battery. Doesn't apply to everyone, wouldn't expect every team to make the same decisions. If you decided that OEM location with a lighter battery was the right call, then that was the right call. We decided that opening up the engine bay was more important, that was the single driver for moving it in our case. We just happened to be able to do it affordably, our battery was in ok shape.
I use LiFe batteries in my 2 cars, so far so good. Cause I dont want to deal with moving heavy battery, and like the extra cranky juice.
What gauge cable should be used for relocating a battery to the rear of a car?
As big as you can find. We mounted ours in the rear passenger floor pan. The front end is heavy enough.
Two gage or 1. Remember if you ground the battery to the frame, run a ground from the frame to the engine block.
Well the battery has been relocated. Ran 2 gauge wire and all seems well. It’s new home is the spare tire well rather than the passenger floor. Just need a few more cable clamps to make the cable run all tidy and neat
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