Adding second battery

[Bobby322 10+ year member]

This is the correct way to wire up another battery right? Is the 2nd fuse necessary? I dont have the ground the second battery again, it will ground out through the other battery?

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[jco1385 5,000+ posts]

This is the correct way to wire up another battery right? Is the 2nd fuse necessary? I dont have the ground the second battery again, it will ground out through the other battery?

2nd fuse is necessary. and i would also fuse the wire from the battery to the amp. i don't like un-fused pos wires. bad things happen to them

 

[Yellow20thAEGti 10+ year member]

Dont mean to thread jack but I have a question to.

Do you need to have the same number of negative runs as you do positive? Ex. If I did 2 runs of Positive do I have to have 2 runs of Negative.

 

[jco1385 5,000+ posts]

Dont mean to thread jack but I have a question to.
Do you need to have the same number of negative runs as you do positive? Ex. If I did 2 runs of Positive do I have to have 2 runs of Negative.

depends on how much power you are running. i only have the pos run and neg thru chassis. aka both batteries grounded to chassis so i have no neg run (for now).

 

[basscort2009 5,000+ posts]

u dont have to run the ground to the back. this is the easiest and best way i have found to run my extra batts

 

[Yellow20thAEGti 10+ year member]

This is what I suspected since the negative is a ground. I guess my next question one be is it necessary to have as many grounds as you do positive runs to the second battery then.

 

[basscort2009 5,000+ posts]

u dont need to run another ground. look at my pic. u only need a pos run and just ground the second batt to the chassis

 

[Yellow20thAEGti 10+ year member]

u dont need to run another ground. look at my pic. u only need a pos run and just ground the second batt to the chassis

So you are saying no matter how many positive runs I do to the second battery I will be fine with just grounding point for the second battery?

 

[basscort2009 5,000+ posts]

yes just ground the back battery however many times u run a positive from the front, IE 4 runs of pos to the back battery, ground the back battery 4 times

 

[jco1385 5,000+ posts]

So you are saying no matter how many positive runs I do to the second battery I will be fine with just grounding point for the second battery?

it's debatable. it depends on how well your car conducts the electricity. personally, i say if you are 2-3k+watts i would go with a pos and a neg run between the batteries.

 

[jco1385 5,000+ posts]

yes just ground the back battery however many times u run a positive from the front, IE 4 runs of pos to the back battery, ground the back battery 4 times

i dont think that is good advice. it depends on the resistance of the chassis.

 

[andrewmoore13 10+ year member]

i have 2 batts and have had 1 run of each between the batts since day one.

only problem is if i ground the amps to the rear battery i get huge alt whine... if not it disappears.

 

[Yellow20thAEGti 10+ year member]

i dont think that is good advise. it depends on the resistance of the chassis.

Well how about 2 runs of positive and 1 negative run between batteries and ground the second battery to the chasis.

 

[basscort2009 5,000+ posts]

they say u need a ground wire as big as a neg right??? ok well if u have 4 1/0 wires run back there for pos and only one 1/0 ground then what do u think is gonna happen....

 

[jco1385 5,000+ posts]

they say u need a ground wire as big as a neg right??? ok well if u have 4 1/0 wires run back there for pos and only one 1/0 ground then what do u think is gonna happen....

same = same

and yes, you want them to be equal. thats why i wouldnt recommend upgrading to 2 runs pos and still running the neg thru chassis. that creates a bottle-neck. if you want to run one pos run, and ground to the chassis, that is (generally) ok. but more pos runs means you need more ground to complete the circuit. so (IMHO) if you run 2+ pos runs, you should do the same for the ground