educate me.. can long grounds cause voltage loss?

[mcsoul 10+ year member]

Probably not as bad a voltage drop as a uni-body non frame.

 

[godhatescivics 10+ year member]

is it possible that the factory battery to be causing my voltage problems i have to g31s and the factory battery and voltage is 12.8 car running nothing on

 

[DammitJames 10+ year member]

is it possible that the factory battery to be causing my voltage problems i have to g31s and the factory battery and voltage is 12.8 car running nothing on

your battery has no use in a car except to stablalize voltage and start your car when your car is running unless the alt cant keep up with the demand the battery does nothing everything is run off the alt when your car is on

 

[DammitJames 10+ year member]

is it possible that the factory battery to be causing my voltage problems i have to g31s and the factory battery and voltage is 12.8 car running nothing on

your low voltage problem sound to me like something in the alt to bat wire try doing a voltage drop on that wire and see if your losing anything u can also try a volateg drop on the alt casing to the neg bat terminal

 

[DBBOOM 10+ year member]

With a ground length of 3'(assuming its of adequate size) you will loose more voltage at the connections than you will through the cable. Make sure your alt and battery are up to par, if so, i'd look at all of my connections(positive and negative).

 

[loopkiller 10+ year member]

id say the grounds going to both of my amps are roughly 3 feet. will this cause voltage loss? I am certain I will need another battery up front. Just want to start with the basics first. I'm pretty sure I can shorten up the grounds, but is it necessary. My amps are seeing roughly 12.2 volts (not good :/ lights dim). thanks!

Since you have that Batcap 200 in the trunk, you should be grounding directly to the battery and then ground the battery to the chassis. That chassis ground should be as short as needed, but since you should be using 1/0 wire, and extra foot or two would not make any difference.

I am already using 1/0 wire for the sub amp, and already have the big 3 done. just wondering if shortening up my grounds would reduce the voltage loss I am having.

No, not using 1/0. It would take more wire than the length of your car to make any measurable difference in voltage.

yup 12.2 at the 4 channel with the car on. both batteries test fine with the car off (12.7-.8) and without the cd player on, the 4 channel test about 14.2. . I have a batcap 2000 in the back, and a duralast (pretty sure it is a stock battery) in the front. reserve on it is 90, and only 500 cca. I am pretty sure I need to throw something else up front.

That 2000 should be enough to run that stuff as long as your alt it healthy. The front battery is not going to help much.

no sorry, I think you misunderstood me. while everything is idle, my amps see about 14.2 volts. its when I crank it up, it hits around 12.2. I just put that second battery in about a week ago. It rest at about 12. 8 though. 1/0 gauge wire, with 250 amp knu fuse holders. the 4 channel i only about 100 W rms, and the sundown 1500.. 1500 rms (though I don't think I quite have it set that high .. yet) haven't tuned the sundown with a volt meter yet was planning on doing it all this weekend. alternator is good but its only 90 amps. define a fully charged battery? They all rest good, or so my volt meter says

12.8v on your 2000 is fully charged. 12.6v on your front battery is fully charged. You need to remove the NEG- connections from you battery to check this.

Yeah I do drive around with my music turned down sometimes. Thanks for all of your help. I think I am going to go back, redo all of my grounds.. and look for another battery up front. since I have a batcap 2000 in the back, should I get another batcap to put up front? or can I put something like a deka, or PM, or kinetik etc up front.

Like I have told you in any of your other 200 posts, keep them the same if you want to run more than 1. I think you are seeing the quality of the Batcap battery first hand however.

 

[vandiar2 10+ year member]

Since you have that Batcap 200 in the trunk, you should be grounding directly to the battery and then ground the battery to the chassis. That chassis ground should be as short as needed, but since you should be using 1/0 wire, and extra foot or two would not make any difference.


No, not using 1/0. It would take more wire than the length of your car to make any measurable difference in voltage.

That 2000 should be enough to run that stuff as long as your alt it healthy. The front battery is not going to help much.

12.8v on your 2000 is fully charged. 12.6v on your front battery is fully charged. You need to remove the NEG- connections from you battery to check this.

Like I have told you in any of your other 200 posts, keep them the same if you want to run more than 1. I think you are seeing the quality of the Batcap battery first hand however.

great stuff. Thanks man, I'm all over it this weekend.

 

[vandiar2 10+ year member]

this is the easist way to tell right here its called a voltage drop take a DMM and put it on dc volts turn the amps on and have em drawing some kinda power(they have to be using power for it to work right) then put on meter lead on one end of ur wire then the other one on the other end of the wire(on the same wire not a + and - still hooked up to the amps or whatever it is) with the amps on and drawing power(playing) the DMM should read 0v anything more means u are losing voltage in your wires this is a common practice in the automotive industry for checking starter and alt wires it will work on the positive and negative wires just make sure ur leads are on the same wire

hey thanks for that tip. I will be doing this soon too. Maybe I do have something improper idk.

 

[vandiar2 10+ year member]

hey one more question while I am at it.. testing grounds with a DMM. so lets say that batcap in the back, if I put the pos lead on the ground spot and then negative lead on the negative of the battery and test for ohms.. I should get

 

[loopkiller 10+ year member]

You should see a very small number of resistance if any at all with a 1/0 wire.

 

[vandiar2 10+ year member]

You should see a very small number of resistance if any at all with a 1/0 wire.

right, im just trying to make sure the ground spot I picked is good. is that the way to test the ground spot? if not.. how do ya do it?

 

[loopkiller 10+ year member]

right, im just trying to make sure the ground spot I picked is good. is that the way to test the ground spot? if not.. how do ya do it?

You would need to put one lead on the ground spot and the other on the front battery NEG- post or the alternator case. Neither of those are going to be easy since they are so far away from your grounding spot in the trunk.

 

[DammitJames 10+ year member]

u do the voltage drop on ground wires too belive it or not if theres a bad ground it will read a voltage drop ohms doesnt measure much rly u can cut half of ur 1/0 wire and still have good ohms thats why we do voltage drops in automotive

 

[blackbonnie 5,000+ posts]

my ground are 20 feet long //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[loopkiller 10+ year member]

u do the voltage drop on ground wires too belive it or not if theres a bad ground it will read a voltage drop ohms doesnt measure much rly u can cut half of ur 1/0 wire and still have good ohms thats why we do voltage drops in automotive

The issue here is that one end of the wire is under the hood and the other is in the trunk. It is hard to get your DMM leads to reach that far. Also, if your leads were that long, I think they would add to the resistance anyways and would skew the results.