Ideal larger than stock Battery Cable SIZE

[68 Sport Satellite]

I believe our cars came stock with 4 AWG battery cables which is what I have now. I'm upgrading my cables to a larger size for better cranking current. I know many of you have reported upsizing to 2AWG, 1AWG and even 1/0 or 2/0 diameter cables. At what size do we reach diminishing returns? I was going to upsize to 1AWG, but if the majority of you have tried that and eventually went with 1/0 or 2/0 I'd like to hear about it and do it right the first time.

Thanks in advance!

 

[kiwigtx]

I believe our cars came stock with 4 AWG battery cables which is what I have now. I'm upgrading my cables to a larger size for better cranking current. I know many of you have reported upsizing to 2AWG, 1AWG and even 1/0 or 2/0 diameter cables. At what size do we reach diminishing returns? I was going to upsize to 1AWG, but if the majority of you have tried that and eventually went with 1/0 or 2/0 I'd like to hear about it and do it right the first time.

Thanks in advance!

A lot depends upon the length of the cable - if you're going stock with the battery next to engine, or if you're going trunk mounted for the battery.

I'm sure our resident Guru will have his slide rule out ready to explain the why's and where's about the calculations required....in his opinion.

 

[dadsbee]

Some just can't lose the pinky ring Rog.. no matter how far it should get shoved.

 

[davek]

mini starters do wonders for cranking,good luck on the cable

 

[zyzzyx]

I went with a 1/0 very fine strand ground cable so it would be flexible and not start
to fray or break. Electrically, I want that baby to Crank! Also going to install multiple
ground wires between the engine and firewall. Don't care if it's "Correct" or not.
Doing my best, but upgrading everything I can as I go. It's my car!

 

[Tony Tee]

I smoked my throttle cable once, when I cranked the 440 without the ground strap bolted on! Extra grounds are not a bad idea!

 

[kiwigtx]

Some just can't lose the pinky ring Rog.. no matter how far it should get shoved.

 

[68 Sport Satellite]

I've been running a mini starter for a long time and it works well. Extra ground strap from firewall to block already installed. Still gets heat soaked though and bigger cables should help. I'm keeping the battery up front. Just trying to decide how big to go on the cables.

As of now I was planning on both positive and negative battery cables being the same gauge (leaning towards 1/0 (same as 0 AWG), but also wondering if one size smaller for the battery ground cable makes any sense.

 

[RJRENTON]

A lot depends upon the length of the cable - if you're going stock with the battery next to engine, or if you're going trunk mounted for the battery.

I'm sure our resident Guru will have his slide rule out ready to explain the why's and where's about the calculations required....in his opinion.

IF you're referring to moi, I still have my slide rule but the batteries are dead....so I must resort to the computer, a canned program, and the ever popular Ohm's Law. To this end, each wire size has a specific resistance, expressed as Ohm's per foot, at the maximum stated amperage of the conductor X the overall length.
There are several examples of how to calculate the overall resistance then using Ohm's Law, calculate the voltage drop of the wire to see if the included voltage drop does not exceed the voltage at the use point (starter motor with battery in the trunk).
I suggest the user perform their own calcs, as each application is different. Additionally, if cost is a consideration, or not, use the largest size wire t
hat you can afford. I can supply typical formulas to do the calcs. Just my opinion of course.....

Engineers often ask how to calculate the resistance of a cable, there is a very simple formula that works well within an ohm or so with copper cable. 19 ÷ by 2.5mm² will give you 7.6 ohms per km. ÷ by 1000 for resistance per meter. 19 ÷ by 4mm² will give you 4.75 ohms per km.Apr 12, 2017
https://www.rs-online.com › how-to...
Hints and Tips - How to calculate resistance of a copper cable
Use this link...i've deleted the previous reference as I errored and posted the wrong list

 

[Mackman]

I am currently (no pun intended) using #2 with a mini starter and it seems more than adequate. If it’s a concern to you, use the largest size you can form and find terminals for that fit your application. If I had my battery in the trunk, I would use at least 2/0. Ground cable from the battery should be the same size as the positive.

 

[Runner 68]

Trunk mount battery here. Went with 1/0 welding cable.
Flexes real nice to get up front to the starter. Only hot while cranking.

 

[RJRENTON]

I am currently (no pun intended) using #2 with a mini starter and it seems more than adequate. If it’s a concern to you, use the largest size you can form and find terminals for that fit your application. If I had my battery in the trunk, I would use at least 2/0. Ground cable from the battery should be the same size as the positive.

YES....EXCELLENT choice for wire size. 2/0 for both positive and negative cables to the engine would be a good choice for a trunk mounted battery application, with, IMO, both crimped and soldered lugs. Mini starters use permanent magnets for the fields resulting in less internal voltage loss (only the armature draws current) which produces more torque. IF you are experiencing the cables getting hot or warm during prolonged cranking, its an indication that there is excessive voltage drop in the wire.....the fix is: up size the wire to the next size larger.
BOB RENTON

 

[CoronetDarter]

I've been running a mini starter for a long time and it works well. Extra ground strap from firewall to block already installed. Still gets heat soaked though and bigger cables should help. I'm keeping the battery up front. Just trying to decide how big to go on the cables.

As of now I was planning on both positive and negative battery cables being the same gauge (leaning towards 1/0 (same as 0 AWG), but also wondering if one size smaller for the battery ground cable makes any sense.

Dwayne, I went with 1/0 cables in the Coronet and the Dart. I don't think there is a point of diminishing returns. 1/0 cable might be "over-engineering", but so what. Of course you'll need larger lugs, shrink wrap and a crimper. I used the spring loaded hammer-pounder crimper. I also drilled a small hole at the front of the lug, and after crimping I heated up the lug and ran solder into the hole, then shrink wrapped.
I was having heat-soak issues on the Coronet a few years ago, and in addition to the 1/0 cables I upgraded the factory 12 ga wire that goes from the starter solenoid to the starter relay with 10 ga wire (brown, to match OEM) and wrapped it in DEI heat shield.
Too bad you're so far away; we could knock this out in a Saturday afternoon.

 

[68 Sport Satellite]

I'm going with 1/0 for both cables. Thanks all.

I can't easily see the connections when under the car without removing the starter, but is there any advantage of using a 45 degree fitting at the starter lug or are straight ring terminals fine?

 

[CoronetDarter]

I'm going with 1/0 for both cables. Thanks all.

I can't easily see the connections when under the car without removing the starter, but is there any advantage of using a 45 degree fitting at the starter lug or are straight ring terminals fine?

The advantage is accessibility, especially with headers. With the 45° terminals I can get to the starter cables through the access hole in the inner fender.

 

[68 Sport Satellite]

The advantage is accessibility, especially with headers. With the 45° terminals I can get to the starter cables through the access hole in the inner fender.

Thanks Rich. I'm trying to picture what you're saying here - my starter terminals are facing up on the passenger side of the starter, with starter itself on the driver's side. How is it possible to access those terminals that way? Any photos? I've got a big block 451 (400 block) with NAPA mini starter. That would be amazing to swap out this cable without removing the starter.

 

[CoronetDarter]

Thanks Rich. I'm trying to picture what you're saying here - my starter terminals are facing up on the passenger side of the starter, with starter itself on the driver's side. How is it possible to access those terminals that way? Any photos? I've got a big block 451 (400 block) with NAPA mini starter. That would be amazing to swap out this cable without removing the starter.

I'll have to look for photos tonight when I get home, or take new ones.

 

[Crackedback]

The cables I build/sell, I use 1/0 thin strand cable. Flexible and carry power much better than the OEM 4ga stuff.

 

[68 Sport Satellite]

I'll have to look for photos tonight when I get home, or take new ones.

Rich, when you did this are you able to see the starter terminals through the inner fender access panel? That panel is so far forward I'm having a tough time picturing it. Or is it just to reach the wrench in there and you go by feel?

 

[zyzzyx]

I think he's talking about the access panel just above the brake distribution block
behind the wheel. It's a straight shot in.