Thread: The Big Three upgrade-charging system

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I am in the process of doing a big three upgrade on my D.D'er a 1994 Astro.

What the big three consists of is a battery with a side mount terminals that is connected to the normal wire harness and then larger cables connected to the top terminals,one for the ground,one from the alt to the battery,and one from the engine to the frame.

Yrs ago I read a article that stated unless the cable size was increased,it wasn't worth doing.

So for the battery to a ground on the frame I went with 0/1 cable and the same size I am going to use for the frame to the engine.The Alt to battery I had to limit the cable size to number 2 cable because the only cable terminal that would fit on the Alt is the number 2.In doing that I am improving the charging cable size.

My question is because of the different size cables from the Alt to the ground wires,am I creating a electrical imbalance??.

So you only have one battery, and your connections to the side terminals are the OEM normally sized battery cables, run as per the OEM installation, and then you are adding a second ground from the top terminal using your 0/1 cable to the frame, and a second direct charging connection from the alternator using your #2 cable? If I understand correctly then no, your difference in cable sizes makes no difference electrically. Your positive from the side terminal is carrying the high amp feed to the starter. Your positive to the top terminal is simply a second path to charge the battery. There is no "imbalance", but I also cannot see that this improves the system in any way, but then I'm a gearhead engineer and my spark chasing classes were pretty limitted, and long, long ago. Others may feel free to educate me on the benefits.

Any and all electrical energy will take the path of least resistance and larger sized wire/cable will offer that path over smaller sized wire/cable if they are connected at the same electrical point. The larger wire/cable will have less impedance compared to smaller wire/cable of the same length.

In a word NO

This link is not the first article I found,but talks about the upgrade.In my case with the Astro,there is a very small ground to chassis stud with a 105 Alt.I have only done so far the battery to ground part of it and today driving the van to a store I saw what appeared on the digital dash gauge a higher charging output than I have seen before.Here is the link:


How to upgrade the Big Three, big 3

Heck Gary, the article says right in the leading paragraph that the "Big Three" is intended for vehicles that are running huge amplifiers on sound systems, which are pulling a ton of amps to power the massive speakers. You did not tell us the Astro Van is a mobile boom box!!

Nope Roger.It's not that.Just looking to improve the charging system.The article I first found(not this one and can't first the first one any longer) was about charging.Heck the radio doesn't work.

I have been fighting a dead short somewhere.So this has been a starting point to combat that.It would just shut off killing everything.Heck the clock after that would have to be reset it was so bad.No codes.Nothing to trace.

I consider on the net home for me and thank you guys for that.I have been keeping quiet about this because I thought it didn't fit in here where the big three update might be useful to someone.

This problem has been holding up my Ole Yellar project through.

Originally Posted by 1gary

Nope Roger.It's not that.Just looking to improve the charging system.The article I first found(not this one and can't first the first one any longer) was about charging.Heck the radio doesn't work.

Just joking a bit, Gary. Here's a link on 12volt.com How to upgrade the Big Three and while the concept is necessary for the guys with the massive audio systems they clearly state that it is also for any high output alternator addition. On my EZ Wire system they provided a second, heavier wire to run from the alternator to the positive starter/battery post just for that purpose, if you have an alternator over about 60 amps.

On yours I sympathize, because chasing a short can be one of the most frustrating things. Have you tried pulling your negative cable and putting a test light between the cable & battery post with everything turned off to check for a drain? Be sure to pull the dome light bulbs or pull that fuse first. If you have a light then you can pull & replace fuses one at a time until the light goes out, then you know your short is in that circuit. I chased one long ago, finally finding that the cigarette lighter element had shorted and was pressed into the socket, and it was my dead short , draining a battery in very short order. All it took was a $2 lighter element!! Must have been God tapping me on the shoulder to quit smoking Relays of seldom used accessories are another culprit, too, or that radio that does not work?? I'd check the radio fuse first!!

Good luck chasing your short!