# Symptoms of a bad ground connection



## ahl395

Hi all

So I've done a bit of research on my question but haven't found a clear answer.

Aside from the obvious symptoms of a bad ground connection like your amp going into protection mode or speakers popping and cutting out, what other problems will you have?

My main question is, will you see a voltage drop?

I ask because I have been told what I thought was a good ground in my system is very bad. I haven't seen any of the obvious symptoms and don't see any substantial voltage drop. (No drop with system low, minimum of 13.5V "bumping" when above idle). 

*If I don't see any voltage drop, do I have anything to worry about?*

And all my background info because I'm sure it will be asked...
Grounds: I have four 1/0 cables going to two ground termination blocks. These blocks were pressed up and held against bare metal and welded. I have been told that it is welded very badly and that is the main problem. In my eyes the weld is just used to hold the block against the frame.
RMS: 2600 W
Peak: 5200 W
Sub: Fi Q 12"
Amps: Hifonics Hercules 4K, 2x Kicker CX300.4
Second battery: XS Power D1200
Electrical: Stock Alt (which makes my voltage drop numbers pretty impressive imo), Big 3, All knukonceptz 1/0 wire

Any input is greatly appreciated. I'll post pics of the ground if anyone would like to see as well.


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## ccapil

Pics will help if you can upload a couple.
So why do you think you have a bad ground? Do you have noise in your system or any voltage or amp issues? Since you say you don't see any voltage drop then why are you worried? Who told you that the ground(s) are bad? They could be wrong?
It's hard to say because usually if you have a bad ground you can get many problems:

Amplifiers going into protect mode
Can cause the amp to clip.
It can make your amp cut in and out or if the amp is restating.
Whining or popping or any audible noise that isn't normal.
Can cause burning or even a fire!

So post some pics of the grounds and the distro block that is welded. Also more info on what the actual problem is, whether it's noise, voltage issues, music playing problems, or any equipment problems or failure. 
For your grounds, did you put them on? If so did you:
Scrape the paint down to bare chassis metal?
Secure the ground with a strong soldered lug and with a bolt and nut?
Check all the grounds, are the all tight and don't wiggle?
Ho long are they? How far from the amps?


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## minbari

resistance in a power system will show up as a voltage drop if you are pulling current. when the system is idle, it will have the same voltage at the amplifier as you do at the battery.

play a test tone at a resonably high level and then measure the voltage right at the amplifier terminals and see what it reads. you shouldnt be dropping more than a few tenths.


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## ahl395

ccapil said:


> Pics will help if you can upload a couple.
> So why do you think you have a bad ground? Do you have noise in your system or any voltage or amp issues? Since you say you don't see any voltage drop then why are you worried? Who told you that the ground(s) are bad? They could be wrong?
> It's hard to say because usually if you have a bad ground you can get many problems:
> 
> Amplifiers going into protect mode
> Can cause the amp to clip.
> It can make your amp cut in and out or if the amp is restating.
> Whining or popping or any audible noise that isn't normal.
> Can cause burning or even a fire!
> 
> So post some pics of the grounds and the distro block that is welded. Also more info on what the actual problem is, whether it's noise, voltage issues, music playing problems, or any equipment problems or failure.
> For your grounds, did you put them on? If so did you:
> Scrape the paint down to bare chassis metal?
> Secure the ground with a strong soldered lug and with a bolt and nut?
> Check all the grounds, are the all tight and don't wiggle?
> Ho long are they? How far from the amps?


Here's a picture of the grounds










(Ignore the black stuff in the middle. We tried to weld one in that spot but it burned a hole through the metal so I used some rubber spray to stop it from rusting around the hole)

Like I said a few people told me this was done horribly because of the bad welding.

I'm not really having any issues. My voltage drop numbers are completely acceptable to me seeing as I have a stock alternator. I put the grounds on, but I did not do the welding. I sanded down to bare metal before welding though. All the lugs are soldered and crimped with a hydraulic hex crimper. The only "issues" I might be having is my amp does seem to clip easily (referring to the clipping indicator on the amp). The bass doesnt seem to hit as hard as I would expect it to for a system of this caliber. Comparing it to my old sub which was only 500W, compared to 2000W of my Fi Q, there are some notes that actually sounded better on my old setup. 

These problems could also be caused by my pre-fab enclosure though. It's too small and I'm in the process of building one a bit bigger, which could solve my problem. The amp does seem to clip easily though when turning it up, so I cant put it as loud as I'd like to. Also, I set the gains with a Fluke DMM.



minbari said:


> resistance in a power system will show up as a voltage drop if you are pulling current. when the system is idle, it will have the same voltage at the amplifier as you do at the battery.
> 
> play a test tone at a resonably high level and then measure the voltage right at the amplifier terminals and see what it reads. you shouldnt be dropping more than a few tenths.


When the system is turned up my voltage drop isn't bad at all. My second battery helps the stock alt out alot. When above an idle it doesnt drop below 13.5-13.6V. And when idling it doesnt usually drop below 13V, although extreme bass songs can bring it down to 12.4V. But thee numbers are pretty good considering my situation. I have a stock 80A alt. Before this system and my second battery I only had about 700W RMS and would drop down to 11.6V at an idle. So almost quadrupling my system wattage and sticking above 13V 90% of the time is perfectly acceptable to me.


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## ATOMICTECH62

The box the subs are in is probably the biggest factor.
It looks like you went through a lot of trouble to get the grounds and wire set up why would you use a prefab(yuk)box for Fi subs.


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## ahl395

ATOMICTECH62 said:


> The box the subs are in is probably the biggest factor.
> It looks like you went through a lot of trouble to get the grounds and wire set up why would you use a prefab(yuk)box for Fi subs.


It was just temporary and what I had at the time. I ran my funds down a little low buying all the equipment and had to pay a few other bills before I could get the materials to build a real box.

It's put together now, just gotta get a few ring terminals and wire up the sub in it.


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## SPLEclipse

Welds don't make the best of grounds, but will work. I don't think the welding is the issue since they're just structural. But...It's difficult to know how well the welds are holding the ground blocks against the contact point. You also need to check the complete ground path after that sheet metal. It needs to make a solid frame connection somewhere, and rubber isolators and crappy weld points to the frame will increase resistance. So it might be a perfectly acceptable ground or not, lol. Like mentioned above, if your voltage is holding under load you're good to go.


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## ahl395

SPLEclipse said:


> Welds don't make the best of grounds, but will work. I don't think the welding is the issue since they're just structural. But...It's difficult to know how well the welds are holding the ground blocks against the contact point. You also need to check the complete ground path after that sheet metal. It needs to make a solid frame connection somewhere, and rubber isolators and crappy weld points to the frame will increase resistance. So it might be a perfectly acceptable ground or not, lol. Like mentioned above, if your voltage is holding under load you're good to go.


Ah okay. Yeah I was questioning whether or not it was a good enough piece of metal to ground on. It's the thickest piece of metal in the trunk so it was the best spot I could use aside from drilling a hole and running it to somewhere underneath on the subframe.

I'm not seeing any abnormal voltage drop like I said, so I guess I don't have anything to worry about ground wise.


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