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Question About Grounding...

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03msc

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OK, so I've searched through various threads on here and haven't found a lot of references to this so I'm going to go out on a limb and risk looking like an idiot by asking the question here. Maybe someone in the future will be curious and it will help them, too...

The question is, when running the power wiring for your radio install, I know to run the power directly to the battery. My question is, as the title indicates, about the ground - do you run it directly to the battery as well or do you just ground it to the body somewhere close to the radio?

The reason I ask is because I was talking to a friend of mine about the install I'm about to do for my mobile rig and I mentioned that I was getting some red & black zip cable to run the power and he asked why in the world I'd run the ground up to the battery when "all you gotta do is find a bolt somewhere, loosen it, stick the ground wire under it and tighten down". I said I thought I had read about noise, etc., from grounding improperly and he looked at me like I was crazy. So, if I'm crazy then tell me! Otherwise I plan to run it to the battery.

Am I right or wrong?
 

mmckenna

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The two vehicles I own have been done differently.
My wife's Ford Escape has a single Motorola CDM1250 VHF with a remote head. The RF deck is located under the center console, with the control head on top of the center console. I ran + & - all the way back to the battery. The + is tied down through a fuse directly to the + terminal on the battery. The - is tied down to the same place on the chassis that the battery - cable connects to. This works fine, no noise.

I had a GMC pickup many years back and I had an Icom UHF installed in it. I had originally run the radio power back to the battery and had both + & - tied down directly at the battery posts. I had a lot of ignition noise. When I moved the - lead to the chassis, to the same bolt that the battery was connected to, the ignition noise went away.

My F150 has two radios in it. Both are remote head, a Motorola CDM1550 VHF and a Kenwood NX-900 800MHz. I ran a #6 power feed from the battery, through a 60 amp fuse all the way back to the space behind the rear seat. Behind the seat I have a distribution block. I pick up the negative side of the battery off a large bolt that holds the seat down. No noise issues. I did run an additional - lead off the battery to the chassis ground to be sure I wouldn't ever overtax the stock one. In addition, I have a piece of 3/4" braid connected from chassis ground to the frame of each radio.


Either design seems to work fine. I could see arguments for doing it both ways. Local grounding of the radio frame can be a useful addition if you are going to run both + & - back to the battery.
If you are running zip cord, then it wouldn't take much more work to do it that way. You can always ground the radio chassis locally, and you can always change it later if you have issues. Most commercial radios I've seen come with power cords that are long enough so that both + & - will reach the battery. I think I've seen some older 100 watt radios with only long + leads and a shorter - lead.

Should be interesting to see what others say, as long as it doesn't turn into an argument. I'd like to see if some of my theories about why each way would be "better" are generally accepted or not.
 

bharvey2

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By and large, you'll get the better installation by running the positive negative leads directly to the battery. The likelihood of picking up noise is greatly reduced. (There are exceptions though as mmckenna pointed out in his post above.

You might want to reexamine the choice of wire. Zip cord doesn't have the toughest of insulation. In an engine compartment with heat and possibly oil, there are more suitable cable types. Maybe something like and SOJ or SJOW as they are designed for harsher environments. Most cables and wire will be marked with their insulation type on the outer jacket.

Good luck with your installation.
 

03msc

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By and large, you'll get the better installation by running the positive negative leads directly to the battery. The likelihood of picking up noise is greatly reduced. (There are exceptions though as mmckenna pointed out in his post above.

You might want to reexamine the choice of wire. Zip cord doesn't have the toughest of insulation. In an engine compartment with heat and possibly oil, there are more suitable cable types. Maybe something like and SOJ or SJOW as they are designed for harsher environments. Most cables and wire will be marked with their insulation type on the outer jacket.

Good luck with your installation.
I am planning to put loom over the portion of the wiring that is in the engine compartment, to help with keeping it clean and maybe help a little with keeping direct heat off of it. Also, I plan to run it up along the top edge of the fender which is as far away from the engine as possible. The b/r zip wire I have is 10AWG. Hopefully it'll be fine.

Thanks, everyone, for the input thus far! Have something to add? Share it!
 

iMONITOR

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As others pointed out, direct connect leaves no doubt.

On older vehicles, corrosion, and loosening body parts can introduce resistance.

On newer vehicle, you have to be VERY careful where you connect anything electrical. Most have what amounts to a complex computer network running through out the vehicles electrical system. If you should short, or disturb that in anyway, you're looking at a big diagnostics/repair bill. Added to that, the use of various plastics, coatings, and rubber between body parts, might not make for a good solid ground connection.

I would think somewhere you might find a good accessory common ground connection, but every vehicle is different.
 

jim202

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Not to add to the know it all out there, there is a couple of thoughts as to why and why not to bring the negative directly to the battery.

Those that stand fast of running the negative to the battery and also put a fuse in the negative wire believe that if you loose the negative ground from the battery to the frame and engine, the radio will be used as the path for the starter motor current. Plus the antenna coax shield will also become part of this path. That is a possibility.

However with that said, the reality of this and the number 10 wire that many of the off shore radio companies supply for a DC feed wire will not survive long if the starter motor even tries to pull it's 300 or more amps it takes to crank a car or pickup. Big trucks is way above this current. You will long discover a problem starting a vehicle before wire and equipment damage occur.

In most cases, the first thing that shows up is the clock setting in your radio suddenly looses the correct time. Your headlights dim way down when you put them on high beam. Your lights go dim when you kick on the air conditioner. These are all pre disaster indications that something including a bad alternator are showing their ugly head. It could even be such a simple thing as the ground wire on the battery to the frame has a poor connection.

It wouldn't hurt to spend an extra 30 seconds under the hood to look at your battery connections and see if any of that white fuzzy stuff is growing on the battery posts. Some baking soda and water can repair that disaster and put it to bed. Might even check to see if the ground wire from the battery to the frame still looks good. Loose that and you won't start your engine.

I have always added a thick jumper from the engine itself to the vehicle frame. In many of the newer vehicles, I would bet that you can't find the ground from the engine to the vehicle frame and or battery. It's just poor design engineering. Plus it makes for a high noise generator when the engine is running.

To each their own in how they feel about running the ground wire of their radio directly to the battery. With or without a fuse is based on who you listen to the most. You can probably ask 6 people about these 2 items and end up with maybe 8 to 10 answers. They are all probably right to some extent. Who is more correct is going to be based on how you understand electronics and high current usage in these vehicles.
 

03msc

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Well, I think the general consensus is that it is best to run it to the battery or to where the ground for the battery connects to the vehicle. jim202, I don't mean anything bad by this but I was somewhat confused by your post (perhaps I just don't have enough experience to follow what you were saying). But I think you, and the others, pretty much agree that it's best to run it to the battery.

As I said in my first post, maybe this not only helps me but will help someone else down the road if they search for a similar answer.
 

ko6jw_2

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Just to add my two cents worth. I have an Icom 706 MkII G that was not operating well and I found that there is a difference between the DC ground and the RF ground. My problems went away when I connected a short ground strap from the radio's ground lug to the chassis of the car. Apparently, the RF grounds from the antenna coax were not sufficient nor was the negative connection to the battery.
 

mmckenna

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I run a Yaesu radio in my truck and I ran both positive and negative power wires directly to the battery, and I haven't noticed any alternator noise or RFI
Yeah, I've done that on some vehicles, and it works just fine. the alternator noise/RFI might be a vehicle specific thing. It wasn't corrosion on the GMC I had, it was a new truck, it was just alternator noise.

As for the chassis grounding, back in the early 90's I had a Yaesu VHF mounted in a truck. It was mounted between the driver and passenger seats. I'd notice the radio would occasionally reset (power off, then power back on). Couldn't figure out what it was. Finally figured out it was static electricity from the cloth seats going through the radio to ground. I grounded the radio chassis and it resolved the issue. Even though it was grounded at the battery, it wasn't enough.
 

gtriever

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We always ground to a point on the vehicle's frame, and as much as possible make all ground connections to that single point. We've seen, due to several different reasons, as much as 10 Ohms between the negative battery terminal and the frame.
 

Mikem001

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How to properly ground

OK, so I've searched through various threads on here and haven't found a lot of references to this so I'm going to go out on a limb and risk looking like an idiot by asking the question here. Maybe someone in the future will be curious and it will help them, too...

The question is, when running the power wiring for your radio install, I know to run the power directly to the battery. My question is, as the title indicates, about the ground - do you run it directly to the battery as well or do you just ground it to the body somewhere close to the radio?

The reason I ask is because I was talking to a friend of mine about the install I'm about to do for my mobile rig and I mentioned that I was getting some red & black zip cable to run the power and he asked why in the world I'd run the ground up to the battery when "all you gotta do is find a bolt somewhere, loosen it, stick the ground wire under it and tighten down". I said I thought I had read about noise, etc., from grounding improperly and he looked at me like I was crazy. So, if I'm crazy then tell me! Otherwise I plan to run it to the battery.

Am I right or wrong?
If its properly grounded to the frame you shouldn't have any issues, (no paint ,grease, or rust) and solid mechanical metal to metal connection with a ring or fork terminal(properly crimped on). Problems usually happen when one of the above listed isn't followed and that will cause interference or intermittent working or other problems.
I personally have never ran a negative cable back to the battery on any of my installs and never had an issue. (besides it being a waste of cable and money, it can also be a pain to run more wires through the firewall)

Best of luck
 

jim202

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Well, I think the general consensus is that it is best to run it to the battery or to where the ground for the battery connects to the vehicle. jim202, I don't mean anything bad by this but I was somewhat confused by your post (perhaps I just don't have enough experience to follow what you were saying). But I think you, and the others, pretty much agree that it's best to run it to the battery.

As I said in my first post, maybe this not only helps me but will help someone else down the road if they search for a similar answer.

What I was trying to imply is that the battery ground to the frame can and does become poor after it ages a number of years. This generally exposes itself as hard slow cranking of the engine when it happens. It also shows up as the clock in the dash radio gets it's time reset to midnight.

Those people that insist that you run the radio high current ground wire all the way back to the battery say you need to put a fuse in line with it to prevent damage to the radio if the battery ground to the frame goes bad. That I have to agree with. But if you don't run it to the battery and use the vehicle frame ground instead, you don't put the radio in that danger. The fuse might not blow before the damage is already done to the radio. This is why the major radio vendors use a short wire on the negative return of the high current feed. They force the installers to use the vehicle frame as the ground return.
 

03msc

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What I was trying to imply is that the battery ground to the frame can and does become poor after it ages a number of years. This generally exposes itself as hard slow cranking of the engine when it happens. It also shows up as the clock in the dash radio gets it's time reset to midnight.

Those people that insist that you run the radio high current ground wire all the way back to the battery say you need to put a fuse in line with it to prevent damage to the radio if the battery ground to the frame goes bad. That I have to agree with. But if you don't run it to the battery and use the vehicle frame ground instead, you don't put the radio in that danger. The fuse might not blow before the damage is already done to the radio. This is why the major radio vendors use a short wire on the negative return of the high current feed. They force the installers to use the vehicle frame as the ground return.
OK, so you are saying that it's OK to run it to the battery and fuse it but, in your opinion, the better option would be a good ground to the frame of the vehicle. Correct? I think I understand now.
 

WA0CBW

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From the installation manual for a commercial 2-way radio:
"Locate a good vehicle ground point. The vehicle central ground point provides the best ground. If this is not available, the vehicle frame provides the best ground. Optimum radio performance can only be achieved with a very low resistance ground connection. Verify that the connections between the battery negative terminal, vehicle chassis, and engine block have low resistance."

If you choose to run a ground wire directly to the battery be sure to fuse it (as mentioned above) to prevent any damage caused by a bad battery ground to frame connection. Keep in mind the antenna ground to the vehicle body also needs to be a low resistance ground.
BB
 

KG7SPS

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It's all about the ground. Grounds strap all doors, hood, and trunk lid to the autos body. Additional ground straps from the battery and engine. If you have an electric radiator fan gound the fan to vehicle frame/ground. Ground your radio chase to ground and ensure the antenna ground is grounded to the vehicle frame at the antenna end. Good grounds all around, eliminate the need to run the negative/ground wire all the way the battery.

Oh yeah, use ferrite cores in all power and transmission lines.
 
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