12v to Radios: Running power cables.

[Airmapper]

So I'm aware of some special considerations for powering radios, but I'm not sure on specifics.

First off I know a complete circuit to the battery is best, no grounding to chassis, and I recall something about twisting the cable as you go?

What I need to accomplish is hard wiring my 2M (50w Kenwood) and a CB (4w Midland 75). Right now they are tying up 2 12v cig ports and I want it all out of the way.

I am also considering some special wiring for accessories on the dash and center console. Some USB power ports, maybe a few 12v cig plugs in different places to run a GPS unit, power a tablet, charge phones, and maybe a row of switches. Basically have a way to expand so I can add electrical as needed from a common point.

One idea I had is to install a power distribution box under the dash (Probably a blue sea box) and go from there. However, with the radios, should I keep them on their own line? I mean they are tied into the vehicles accessory wiring now with no reported issues. Also, can the 2 radios share a common main line, or should I keep them separate all the way to the battery?

And, do I want to avoid running coax along with power? Looks like I'll need to add another coax thru the firewall soon. That will have 2 antennas (well 3 if you count broadcast FM) on the hood, and an unused coax to the roof out the rear.

Thanks for any advice.

 

[Frdmskr]

First get the 2m off the cigarette plug. That plug is not rated for that. Could cause a fire.

Next, go to K0BG.com and read up on ideas. No reason to twist anything.

Third, you are looking at a major wiring job. That is a really good thing. Look at how some folks wire up for fridges for ideas on wire gauges, fusing, etc. that way you can expand in the future with less work.

Antennas running through the firewall with power should be fine at 2m or for CB.


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[Airmapper]

Thanks. I forgot how much K0BG had on this. Yeah I do need to get the 2M off that plug, I only put it on there for temp use but it's stayed on longer than I planned.

I really wanted to incorporate the radio wiring into the main wiring job, kind of make myself an interior wiring hub. My main concern was interference from other devices. I don't have a fridge now, but I may at some point, and an inverter, so I need a good power lead run to the rear.

 

[Oldmancrash]

I built a 96 tacoma last year for a 4x4 trip. I ran dual batteries up front. I mounted a blue sea box on the passenger side kick panel under the dash. Ran 4' custom built 0 AWG cables from the blue sea through a hole in my firewall to the spare battery for both positive and negative cables. I ran my 2meter, cb, USB/cigarette charger, power inverter, stereo, LED light bar, 4 LED light pods, T-max dual battery controller all on their own circuits to the blue sea. I had no noise issues and everything ran at the same time with no issues. Plus with everything wired to my spare battery it left my main battery for starting and truck essentials. I have never heard of twisting cables. I also wired a blue sea in the tailgate area inside my topper for accessories in the rear of the truck but that is another story LOL

 

[4x4junkie]

Agreed, interference on the DC power side of things isn't too likely if all of your wiring is of adequate size (no more than 3% voltage drop at the full amount of current you intend to use). The only thing you could potentially run into is an audible hum (power ripple) from say, a fridge motor or an inverter getting through the distribution hub to your radios and/or a piece of audio gear... This is easily eliminated with a simple filter capacitor (25,000-50,000µF) connected across the DC line right at the distribution hub should it occur.

What is far more likely to happen with devices like fridges, inverters, USB chargers, etc. is the device itself radiating interference straight into the air that is subsequently picked up by your radio's antenna. Not much you can do about this outside of adding filters (RFI chokes, feed-through caps, shielding, etc.) to the device that is generating the interference (and is something I had to do to my own Edgestar fridge and a USB charger... My 1500W inverter is exceptionally noisy also, though I don't use it often enough that I've bothered disassembling it to put filters inside it).

 

[PhulesAU]

x2 on using a blue sea power center. Keep your radio gear on a separate harness from the factory one. It will reduce weird issues.

 

[Robert Bills]

. . . What I need to accomplish is hard wiring my 2M (50w Kenwood) and a CB (4w Midland 75). Right now they are tying up 2 12v cig ports and I want it all out of the way. . . . I am also considering some special wiring for accessories on the dash and center console. Some USB power ports, maybe a few 12v cig plugs in different places to run a GPS unit, power a tablet, charge phones, and maybe a row of switches. Basically have a way to expand so I can add electrical as needed from a common point. . . .

I am a firm believer in the KISS principle and also that CB and Ham radios should be wired directly to the battery and not share the circuit with other appliances. However, for my Xterra I decided that I only needed one power wire run for both radios as only one will be transmitting at a time. (Any concern for interference created by the two radios on one circuit proved to be unwarranted after completion and testing of the install).

I ran 10 gauge zip cord (+ & -) from the battery through a fuse to the firewall, across the firewall to the driver's side, and through the existing grommet next to the steering column to the interior. From there I ran it to the center of the dash, under the center console to underneath the passenger seat. In hindsight, 12 gauge would have been sufficient.

This was the wire, available here: https://www.aesham.com/product/ham_..._radio_accessories_powerpoles/powerwerx-by-t/):

The power wire is attached to the battery clamps with ring terminals and is fused at the battery to protect the wire. The factory supplied fuse holders for the radios are retained to protect each appliance.

Note that the power wire is not switched through the ignition. I prefer to be able to monitor my radios when the engine is not running or the keys are in my pocket. I have done it this way since the 1960's. Although I have forgotten to turn off my radios from time to time, it has never resulted in running down my starting battery to the point of not being able to start my engine.

At this time the only other aftermarket electrical accessories inside my cab are a GPS unit and a Bullydog monitor. For the Bullydog I tapped into the unused circuit for heated seats. Easy-Peasy. My GPS is a handheld Garmin Map60csx in a Ram mount, powered through the factory always-on 12v socket in the dash. There is no need to hardwire this type of GPS. If I were to convert to a permanently mounted GPS I would use a fuse tap to tap into an existing circuit because a GPS uses so little power.

If I ever decide to add multiple circuits for things like fridges, auxiliary lights, etc. I will probably mount a Blue Sea fuse block. Even then, I will continue to run an independent power wire for the radios and not power them through the fuse block.

 

[Airmapper]

Thanks for all the input.

I might go ahead and do the radios separate. I like what you put up there Robert, zip cord and connectors looks easy to keep tidy. While I'd like it to all be from a fuse box, the radios separate will be quicker and require less planning, also if I want to do anything fancy like optional key on hot or anything with my distribution box, the radios will be always hot which I also prefer.