Power for Mobile Install

[Bulldogarcher]

I'm currently working on installing a mobile dual band radio, and while looking at where to run my power supply, I realized I already had power run into the cab using 8 gage wire and to a 4 function switch box for some emergency led lights for use as a volunteer for the local fire department. A clean single connection to the battery would always be better, but would I run into any major problems with splicing into this to power my radio? As someone new to radio installs I was curious before moving forward if this would work without problem or if its just safer to go direct to the battery.
The 8 gage wire starts with a 8 gage inline fuse currently with a 10 amp fuse in it, and is connected direct to a battery box while is just off the battery. The wire runs into the cab at a rubber grommet in the fire wall then to the 10 gage pre-exisitng power wire to the switch box.

 

[SteveC0625]

I'm currently working on installing a mobile dual band radio, and while looking at where to run my power supply, I realized I already had power run into the cab using 8 gage wire and to a 4 function switch box for some emergency led lights for use as a volunteer for the local fire department. A clean single connection to the battery would always be better, but would I run into any major problems with splicing into this to power my radio? As someone new to radio installs I was curious before moving forward if this would work without problem or if its just safer to go direct to the battery.
The 8 gage wire starts with a 8 gage inline fuse currently with a 10 amp fuse in it, and is connected direct to a battery box while is just off the battery. The wire runs into the cab at a rubber grommet in the fire wall then to the 10 gage pre-exisitng power wire to the switch box.

You missed the most important info:

What is the current draw of the radio as specified by the manufacturer?

What is the current draw of all your planned lighting and other equipment that you want to run off this 8 gauge wire?

What is the length of the run from the battery to your distribution point on the 8 gauge wire?

This info is critical to answering your question.

 

[Kb2Jpd]

You missed the most important info:



What is the current draw of the radio as specified by the manufacturer?



What is the current draw of all your planned lighting and other equipment that you want to run off this 8 gauge wire?



What is the length of the run from the battery to your distribution point on the 8 gauge wire?



This info is critical to answering your question.

Hi from Adam Kb2Jpd in Brooklyn NY

Look at the power wiring coming out from the mobile radio. Is any of the wiring in your aftermarket wiring harness as thick or thicker than the heavy gauge power wire?

If not, run your own or have someone professional install the radio. Need to check if your vehicle has a special manual for commercial radio installation, some do where they advise best practices so you have the best install.

Don't forget to add supplement insurance for the additional gear.




Sent from my iPhone using Tapatalk

 

[SCPD]

Hi Bulldog
.
I am sure you are about to get a lot of advice on your question. I will be one of the many to offer you mine.
.
I'll give it from two perspectives- as a Ham-- and another as a user of professionally installed two-ways.
.
First- the Ham-- What you propose to do- by connecting into your already heavy duty 8 guage wire sounds fine to me- I am assuming this will be for a relatively low power (50 or so watt) V/UHF transceiver? And everything is, of course, fused ? There *maybe* some RF hash from your strobe lights, but I doubt it- and you'd probably have it anyway, irregardless. As a Ham I'd say "go for it" (In my own vehicles I do things in very similar ways.)
.
Ok, now as the professional-
We have several GMC's- Blazer's and such used in in field work that have assortments of radios- 100 watt low band mobiles, 150 watt HF SSB transceivers, UHF trunk'd stuff---- you get the picture.
.
In these vehicles the power installations are stricter. Each radio has it's power cables run directly to the battery-- both the (+) and the (-). And of course both sides are fused. The negative is run directly to the battery for several reasons- as explain'd by our radio shop manager (when curiosity prompted me to ask) -
.
"If for any reason the frame connection between the vehicle and the battery becomes loose, or corrodes to a resistance joint- you do not want the starter or the other vehicle electronics to find their new ground thru the radios, their coax antenna runs etc."
.
That made sense once I ponder'd it out.
.
The other reason for the direct connection was to lessen any chances of voltage spikes from the starter, air conditione/heaterr blower motor, windshield wipers etc. from getting into the radios thru a common ground.
.
Of course the power requirements of the radio will be a factor. A little CB radio can run off anything... a different story for 150 watt HF Sideband transceivers.
.
Taken all and all- I think your on good track Bulldog. I think you'll be fine hooking up your radio as you have planned............
.
.
.................................................CF

 

[cmdrwill]

Recommend a separate 'main power' cable for the lights, siren, ect. The newer light. strobe, siren, stuff has some nasty hash/noise that seems to get into the radio, especially on transmit. Had to re do a bunch of police cars due to that.

And on newer vehicles you have to ground to the frame/body, due to the vehicle battery management senses on the negative battery cable. We ground near the radio and lighting/siren 'boxes'. No long ground/negative leads.

 

[rescue161]

We never run anything to the negative terminal on the battery. Always ground at the equipment. The shorter the ground wire, the better.

 

[mmckenna]

Strobes and especially some cheap LED lighting can be real noise generators.

You could certainly try it, however you'd need to increase the fuse size. Based off an 8 gauge wire at ~probably~ around 15 feet long (generous), you'd not want to pull more than about 30 amps total. A basic dual band VHF/UHF amateur radio is going to pull 15 amps or less. You should be just fine with the wire size you have.

If the noise is unacceptable, then just run a second 10 gauge power feed to the battery for your radios.

 

[prcguy]

For radios, a direct ground wire to the battery negative post is better. As others have mentioned it picks up less noise and can actually be less resistance to the battery compared to a long run of steel sheet metal with questionable bonds, then eventually the ground lead from the battery to the frame or starter.

For HF radio installations, additional grounding from the radio to the vehicle body with the shortest and widest braid is recommend for a good RF ground, however you can sometimes create a ground loop due to the difference in ground potential. This usually shows up in remote control head radios where the radio might be in the trunk and the control head is in the cab at a different ground potential. In these cases ground currents can flow on wire shields and induce noise into audio lines inside the shield.
prcguy

We never run anything to the negative terminal on the battery. Always ground at the equipment. The shorter the ground wire, the better.

 

[rescue161]

Our shop is not allowed to waiver from the install manuals of the radio manufacturers. It has been beaten into our brains that our warranties will be voided if we don't follow the install manuals. Both Harris and Motorola state specifically to ground the radio at the nearest ground point.

 

[davidzimmerman]

2006 ford escape

i had a 1994 ford crownvic got this escape few months ago and did my install like i have always done.
i got some hide-a-way LEDS from SuperiorLED when on i get noise on my FT-90 i ran a #8 from the battery for ground to the rear where i have everything mounted and wired for Hot and Ground.
i have tried everything to stop the noise from these LEDS still a problem i can't seem to fix.
i did ground them to the body for a SHORT ground still same problem.

 

[AI7PM]

If you feel you must run Negative to the battery as well, don't run the Negative directly to the battery post on newer vehicles. Run it to the pigtail that comes off of the battery that, usually, bolts to a ground point on the fender or other metal structure. This still gives you a direct path to the battery, but the pig tail goes through the loop sensing device that is part of the vehicle computer's battery monitoring function.

 

[mmckenna]

I agree. I've done installs where connecting the negative lead directly to the battery resulted in alternator whine issues. Moving the negative connection to the body addressed that.

It's also an option to ground the radio chassis in addition to all this.

 

[davidzimmerman]

i will try moving the ground from the battery to the fender ground and maybe a ground to the radio chassis see what happens.

 

[SCPD]

Oh, you're making me nervous K5BBC ...
.
I admit that in my own vehicles I wire the hot line directly to the (+) battery terminal and the ground to the vehicle chassis-- If it is going to take a direct negative-to-the-battery to save me then I'm
........"throwing caution to the wind and letting the devil take the hind most."
.
Never in my mobile radio years have I ever had a problem with a faulty ground connection, a 'spike' (knocking-on-wood ) nor have I ever met anyone that has- and its something I had not, quite frankly, thought much about. Until your Post (laffing )
.
We are due to get new 'Ute's this Fall.... and many of the radios will be retrofited into them. I am going to *assume* the radio shop guys know about the pig-tail thing and the battery status monitoring circuits that revolve about new cars-- but ........!
.
Not that I can do much about what the motor pool does to these vehicles- but sometime soon (as in post Independence Day) I think I will pay the radio shop a 'diplomatic' visit.... if nothing else, for my own elucidation. I am sure they will tell me to mind my radars and send me packing... (smiles) Thank you for that heads up, however
.
__________________________________________
.
A Post Script
.
The further mention of the emergency lights and RFI brought a smile. For some reason, our vehicles come with those strobe roof top light bars-- "Blue and Reds" the motor pool fellows call them. Why my Agency thinks we need them is something I have just assumed and never questioned- though I have instructed my guys that they are * Not* ! to use them unless the Apocalypse is occurring-- besides, they do tear up the 2-way radios something awful, despite what the Shop has tried .....,, ferrite inductors, bypass capacitors- nothing works.
.
I will concede, however, they can make for that occasional colourful remote site grand entry - but lights only- they've given us no sirens.............................
......... and No Pizza Runs !.......

.
.
..........................................CF

 

[FFPM571]

i had a 1994 ford crownvic got this escape few months ago and did my install like i have always done.
i got some hide-a-way LEDS from SuperiorLED when on i get noise on my FT-90 i ran a #8 from the battery for ground to the rear where i have everything mounted and wired for Hot and Ground.
i have tried everything to stop the noise from these LEDS still a problem i can't seem to fix.
i did ground them to the body for a SHORT ground still same problem.

Buy cheap Chinese made LED's get noise....simple enough

 

[wrath]

I use whelen Linz6 and Ion trio and get zero noise on my IC 7000 or Kenwood 710g ,+/- both with direct battery conections .

Sent from my SM-T810 using Tapatalk

 

[jim202]

Welcome to the group here Bulldog. You have started off on stirring up the decades old question "Do I ground my radio to the frame or body of the vehicle, or do I ground it right at the battery"?

As expected you got an ear full of feedback. I have been in this radio install and service field for about 50 years now. Have heard it all. Most of my work has been in the public safety area for both police and fire agencies. Throw in a number of public works departments while we are at it.

In not trying to stir the pot, I will say that in all those years and untold vehicles, I have never seen a radio damaged by the vehicle starter wiring and battery ground strap failure. Yes I have seen a number of vehicles that have had poor, loose and corroded ground connections between the battery and frame / body.

Generally when the battery ground strap starts to develop a problem, the driver starts to complain that the engine won't turn over or it's turning over really slow. The mechanic checks it out and corrects the problem.

If you try and draw out the current path between the starter motor and the battery, you see that there is a direct connection between the hot post of the battery and the starter. The ground can be some what confusing. Remember the engine is mounted on rubber shock mounts to keep the vibration from the engine getting to the frame. For the most part the exhaust system is also shock mounted to allow for movement of the pipes as the engine twists as you hit the accelerator. So what is left for the return from the engine to the low side of the battery? In almost all cases you will find a flexible braided strap going from the engine someplace to the frame / body of the vehicle. On the big trucks, you generally can find an actual heavy wire from the engine block to the return of the battery.

Given these facts, you can draw your own conclusions on the possible paths that both informed and misled people on here pass along some wife's tales and some truth. Also over the years, you will find that just about every commercial radio vendor I have seen, excluding the off shore ones, only provide a short ground wire on their power ground cables. The only fuses provided is in the long red wire going to the battery and the control head ignition control to turn the radio on or off with the ignition key.

I use to get involved with what is right or what is wrong. You won't win. Someone who thinks they know more than you will always challenge you. So your on your own to decide which way is better or why that is so. History of damage doesn't cut it in this discussion. It boils down to who has the loudest keyboard.

Oh, another point that didn't come up in this thread yet, is there are those that will tell you there is the path of current flow through the radio antenna coax for the starter motor to be able to draw current. Just thought I would mention that before the crap starts over that topic.

 

[prcguy]

I agree with Jim, never heard of a radio being damaged by a faulty starter ground wire where it tries to draw current through the radio leads. In my opinion a mfr who insists you fuse your negative lead should also insist you put a metal shield over the radio to prevent damage from meteors. The probability between the two seems to be about the same.

BTW, I don't have quite as much install experience as Jim202 but probably within 5yrs of his.
prcguy

Welcome to the group here Bulldog. You have started off on stirring up the decades old question "Do I ground my radio to the frame or body of the vehicle, or do I ground it right at the battery"?

As expected you got an ear full of feedback. I have been in this radio install and service field for about 50 years now. Have heard it all. Most of my work has been in the public safety area for both police and fire agencies. Throw in a number of public works departments while we are at it.

In not trying to stir the pot, I will say that in all those years and untold vehicles, I have never seen a radio damaged by the vehicle starter wiring and battery ground strap failure. Yes I have seen a number of vehicles that have had poor, loose and corroded ground connections between the battery and frame / body.

Generally when the battery ground strap starts to develop a problem, the driver starts to complain that the engine won't turn over or it's turning over really slow. The mechanic checks it out and corrects the problem.

If you try and draw out the current path between the starter motor and the battery, you see that there is a direct connection between the hot post of the battery and the starter. The ground can be some what confusing. Remember the engine is mounted on rubber shock mounts to keep the vibration from the engine getting to the frame. For the most part the exhaust system is also shock mounted to allow for movement of the pipes as the engine twists as you hit the accelerator. So what is left for the return from the engine to the low side of the battery? In almost all cases you will find a flexible braided strap going from the engine someplace to the frame / body of the vehicle. On the big trucks, you generally can find an actual heavy wire from the engine block to the return of the battery.

Given these facts, you can draw your own conclusions on the possible paths that both informed and misled people on here pass along some wife's tales and some truth. Also over the years, you will find that just about every commercial radio vendor I have seen, excluding the off shore ones, only provide a short ground wire on their power ground cables. The only fuses provided is in the long red wire going to the battery and the control head ignition control to turn the radio on or off with the ignition key.

I use to get involved with what is right or what is wrong. You won't win. Someone who thinks they know more than you will always challenge you. So your on your own to decide which way is better or why that is so. History of damage doesn't cut it in this discussion. It boils down to who has the loudest keyboard.

Oh, another point that didn't come up in this thread yet, is there are those that will tell you there is the path of current flow through the radio antenna coax for the starter motor to be able to draw current. Just thought I would mention that before the crap starts over that topic.

 

[davidzimmerman]

FFPM571 i did NOT know at the time the SuperiorLEDS was cheap Chinese made LED's i have Whelen Vertex's NO NOISE i told them about my problem it was blamed on my install i have been doing vehicles for 25 years so again i did not know these was CHEAP CRAPY LEDS lol

 

[AI7PM]

.......

Also over the years, you will find that just about every commercial radio vendor I have seen, excluding the off shore ones, only provide a short ground wire on their power ground cables. The only fuses provided is in the long red wire going to the battery and the control head ignition control to turn the radio on or off with the ignition key.........

That^^^^^^ All of the other standard comonents in the vehicle will ground to chassis as well,

The rest of his post was spot on too. (Just my opinion of course)