whats the best way? multiple batteries - help

[blue 10+ year member]

Huh? The metal in the car's frame has more resistance than 1/0? I don't think so but not sure how to prove it....

It's VERY easy to prove .... All you need is a multi-meter to prove it. Run one end to the main battery ground under the hood , and the other to the spot on the car's metal you want to ground to. Measure the resistance between the two points.

Next measure the resistance between both ends of a piece of 0 gauge copper wire that is 12 ft long ..... Copper is a MUCH better conducter than carbon grade steel.

We have done this test numerous times at my shop , so I know first-hand what you will find.

 

[t-money 10+ year member]

running a piece of 0 guage for ground from one batt to the other will cost more money(i'm willing to pay if it makes a difference), so if i grounded the batt in the trunk to the body, will it not still work fine? if i don't get any noise, can i not assume everything is o.k? again thanks for any help

 

[t-money 10+ year member]

i was wondering, since i already have one run of 4 guage going to my trunk, could i not just run another 4 guauge and attach both 4 guage power wires to my batt in trunk, instead of running a new 0 guage wire to batt in trunk. sorry guys again first time with multiple batts.

 

[Reidk 10+ year member]

My friend and I both do it this way...I have a deep cycle battery in the trunk (similar to a yellow top) and a normal battery under the hood. I ran 4 gauge positive amp wire from my battery under my hood to the battery in my trunk. I grounded the battery in my trunk to the floor. I ran 4 gauge wire and fuse from the battery in the trunk to my amp and grounded my amp to the floor. 0 gauge is not needed standard battery cables- negative and positive are only 4 gauge. Save the money and go with 4 gauge wire. Use the zero gauge wire for the amps.

This works too...my friend went through 4 alternators in a year then he bought a deep cycle and ran it EXACTLY like I just explained it...and whatta ya know problem solved.

 

[lilmaniac2 5,000+ posts]

Huh? The metal in the car's frame has more resistance than 1/0? I don't think so but not sure how to prove it....

I know how to prove you wrong //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

i have 4 runs of 1/0 2 power and 2 ground.. with the grounds unhooked my amp turns off b/c of low voltage ( drops below 11 volts ) with the grounds hooked up it stays above 11 v ( actually around 11.3-11.4)

run 1/0 and 4 gauge for the big three was a waste.... its such a small amount of wire it doesnt make sense to do it in anything other than 0 gauge....

the whole reasoning behind upgrading the wire is to be larger than stock... most stock wires are between 8 and 4 gauge... seems to me that it would be better to use 1/0, but my philosophy is u can never have too much wire

do a run of 1/0 of both ground and power to be safe

 

[lilmaniac2 5,000+ posts]

My friend and I both do it this way...I have a deep cycle battery in the trunk (similar to a yellow top) and a normal battery under the hood. I ran 4 gauge positive amp wire from my battery under my hood to the battery in my trunk. I grounded the battery in my trunk to the floor. I ran 4 gauge wire and fuse from the battery in the trunk to my amp and grounded my amp to the floor. 0 gauge is not needed standard battery cables- negative and positive are only 4 gauge. Save the money and go with 4 gauge wire. Use the zero gauge wire for the amps.
This works too...my friend went through 4 alternators in a year then he bought a deep cycle and ran it EXACTLY like I just explained it...and whatta ya know problem solved.

I hope this battery you are useing is a sealed batt... wouldnt want u dieing from the nice fumes some batts expell.

i really hope you realize you could probably avoided using 2 batts if you only wouldve used correct wiring.

using zero gauge to the amps makes less sense than anything else u stated. The run for the amps is going to be the shortest run therefore it can be the smallest sized b/c of the voltage drop across said wire is going to be minimal

edit also note that he said the BEST way to do this... the best way would be to use 0 gauge... the cheap 4 gauge solution is definately not the best

 

[Reidk 10+ year member]

i have 1.5 liter engine with an 80 amp alternator my head lights were more like strobe lights...sorry i never said it was the best way. But what I'm saying is that 4 gauge wire is big enough and it's matched with the alternators standard 4 gauge wire. my friend has been running his system this way for over 3 years and his amp is a 1000d memphis 1100 watt rms amp. Why would 0 gauge be pointless to run from the back battery to the amp? That's like saying it's pointless to run 0 gauge wire...and don't forget that the wire going from your alternator is 4 gauge (unless you changed it) that means if you ran 0 gauge wire it would be like this.... "alternator would be hooked to the battery with a standard (used on all vehicles) 4 gauge positive wire, that battery which is charged off a 4 gauge wire would then have a 0 gauge wire ran to the rear battery. so you said it yourself there will be a voltage drop from the 4 gauge to the 0 gauge that doesn't make sense. That's why I originally said don't use 0 gauge use 4 gauge. If you do it you will see that 4 gauge is fine.

The battery is not safe for the car it says on the side that it can cause cancer...but i have a nicely sealed trunk and i ride with the back seat up usually.

 

[Reidk 10+ year member]

actually 4 gauge positive wire is what goes to the starter. the wire from your alternator to battery is actually 6 gauge.

 

[blue 10+ year member]

i have 1.5 liter engine with an 80 amp alternator my head lights were more like strobe lights...sorry i never said it was the best way. But what I'm saying is that 4 gauge wire is big enough and it's matched with the alternators standard 4 gauge wire. my friend has been running his system this way for over 3 years and his amp is a 1000d memphis 1100 watt rms amp. Why would 0 gauge be pointless to run from the back battery to the amp? That's like saying it's pointless to run 0 gauge wire...and don't forget that the wire going from your alternator is 4 gauge (unless you changed it) that means if you ran 0 gauge wire it would be like this.... "alternator would be hooked to the battery with a standard (used on all vehicles) 4 gauge positive wire, that battery which is charged off a 4 gauge wire would then have a 0 gauge wire ran to the rear battery. so you said it yourself there will be a voltage drop from the 4 gauge to the 0 gauge that doesn't make sense. That's why I originally said don't use 0 gauge use 4 gauge. If you do it you will see that 4 gauge is fine.
The battery is not safe for the car it says on the side that it can cause cancer...but i have a nicely sealed trunk and i ride with the back seat up usually.

If you only knew how many systems I have in my shop , that we have ripped out ALL of their 4 ga wiring and re-installed 0 gauge everywhere , and then had the dimming headlights STOP ....

If you are running only 4 ga in a car , then switching to 0 gauge right before the amps , you have accomplished absolutely NOTHING. That is perfectly azz backwards.

 

[blue 10+ year member]

running a piece of 0 guage for ground from one batt to the other will cost more money(i'm willing to pay if it makes a difference), so if i grounded the batt in the trunk to the body, will it not still work fine? if i don't get any noise, can i not assume everything is o.k? again thanks for any help

You can do it that way , but if you pick up noise , or if your headlights dim , you will just end up having to run another 0 gauge wire to your trunk any way.

Look at it this way .... You have a 0 gauge for the positive going to the second battery , and the current flows very well. Then you ground to the car's metal, which does NOT flow current as well. Now your positive and negative is not conducting current equally ..... this makes resistance , which lowers your voltage and makes your alternator work harder.

 

[blue 10+ year member]

i was wondering, since i already have one run of 4 guage going to my trunk, could i not just run another 4 guauge and attach both 4 guage power wires to my batt in trunk, instead of running a new 0 guage wire to batt in trunk. sorry guys again first time with multiple batts.

Two 4 ga runs does NOT equal one run of 0 gauge. Dude .... you asked what is the " best " way ..... I've told you the best way. You can now either do it , or not.

 

[Reidk 10+ year member]

probably so...I just know the way I do it works for me and the people around here. And when using 2 batterys the size of the wire doesn't really matter as long as the battery is getting power. What matters is the size of wire from the battery to the amp. like i said after i corrected myself your battery under your hood is charged off a 6 gauge wire running from the alternator. As soon as that lil tiny wire hits the battery the battery will still put a full current out even though it's got a little wire charging it. that would explain how systems with only one battery work better with 0 gauge. and that would also explain why 0 guage would work best from only the battery in the back to the amp. because that battery in the back would have a full charge regardless of the wire size....well you wouldn't want to go to small and melt it or anything.

 

[blue 10+ year member]

probably so...I just know the way I do it works for me and the people around here. And when using 2 batterys the size of the wire doesn't really matter as long as the battery is getting power. What matters is the size of wire from the battery to the amp. like i said after i corrected myself your battery under your hood is charged off a 6 gauge wire running from the alternator. As soon as that lil tiny wire hits the battery the battery will still put a full current out even though it's got a little wire charging it. that would explain how systems with only one battery work better with 0 gauge. and that would also explain why 0 guage would work best from only the battery in the back to the amp. because that battery in the back would have a full charge regardless of the wire size....well you wouldn't want to go to small and melt it or anything.

No man .... You are still simply WRONG. Please don't confuse this guy asking for help , when you are fundamentally wrong.

#1 - " What matters is the size of the battery to the amp " you said. This is WRONG. What matters is the size of the wiring BEFORE the battery !

#2 - Saying the under hood battery is charged by a 6 ga wire from the alternator is also WRONG .... Because the FIRST thing everyone should do is replace this wire with 0 gauge ... This is part of the Big 3.

Let me respectfully educate you here , and you can then make your system even better ......

Your car's entire electrical system stems from the alternator and battery. If you don't upgrade here to begin with , NO OTHER wire in the system is going to matter !

You first have to upgrade the alternator's ground wire , and positive wire to the battery. This get's the MOST current to the battery. You then have to upgrade ALL of the battery's grounds , as well as ALL under hood engine block to chassis grounds , and ANY OTHER main grounds under your hood. This maintains the high current that you have coming from the alternator's upgraded wiring. You next have to get the runs from the battery back to the amps ran with the SAME size upgraded wiring .... This continues keeping the current as unrestricted as possible , and lastly , you have to ground with the SAME upgraded size wiring.

This is THE CORRECT WAY to do it, and there is no substitute. HTH

 

[Reidk 10+ year member]

alright I agree with that. but I'm not gonna go through all that. I got my system to be able to hit as hard as i want with my car idleing or simply turned off completely and I have no problems so i'm not gonna mess with anything else.

 

[blue 10+ year member]

alright I agree with that. but I'm not gonna go through all that. I got my system to be able to hit as hard as i want with my car idleing or simply turned off completely and I have no problems so i'm not gonna mess with anything else.

If it's not broke , don't fix it ! //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif