Single under-dash power source for aftermarket accessories

**BMKal** · 22nd April 2016, 11:17 AM

I'm actually in the process of making up a power supply box to go under the dash to eliminate having multiple accessories plugged in via piggy-back plugs etc to the two cigarette lighter sockets. The gear is all on the table out on the back verandah.

I'm using a Narva fuse box, so all accessories will be individually fused. For power, I am running two wires from the Traxide cable which runs behind the drivers side kick panel - one of these cables will feed three or four fuses so that I have constant power supply for accessories which need it (such as phone cradle & dash camera). The other cable will run via a relay to the remaining fuses so that, even though the power is coming from the auxiliary battery, it is switched off when the ignition is turned off. The relay will be "switched" from an existing ignition controlled power source (I've read that there's one easily accessible in the back of the headlight switch panel). The "switched" power supply / fuses will supply things like sat-nav / TPMS and radar detector so that I don't have to turn them off every time I get out of the car.

My UHF radio already has a direct supply from the main cranking battery, so no need to touch this.

Pretty easy to make up yourself - for me it's just been a matter of making the time to do it in between other jobs. The gear for this has all been on the table outside for a couple of weeks now ..................

**scarry** · 22nd April 2016, 06:29 PM

I started something similar to what BMKal is doing.
i ran mine from one of the two Merrit plugs i have in the rear of the vehicle,that are wired into the auxiliary battery,part of the traxide set up.

I didn't get it completely finished,apart from a connection for the hand held spotlight.

Tombie · 22nd April 2016, 06:33 PM

Or you can grab this... Not cheap but easy!

http://fuzeblocks.com/index.php?pid=10

**haydent** · 27th December 2023, 01:46 PM

Originally Posted by AnD3rew

An experienced 4wder advised me to ensure the UHF is powered directly and not through ignition for two reasons.
- if you are at a campsite and expecting friends to join you you can leave the ignition off and the UHF on to hear approaching friends and guide them in to you.
- if you are the driver and have the keys in your pocket and fall off a cliff it allows your passengers to get on the radio and call for help even if hey don't have the keys.

I took his advice and while (knock on wood) I haven't needed it for the second reason, I often use it for the first reason.

the flip side of this is that if you manually have to turn your radio on/off every time you drive the car you end up leaving it off plenty of times and potentially miss things, so i wire to acc, the noise thing is a furphy with modern uhf, maybe in the 27mhz am cb days...

**haydent** · 27th December 2023, 02:29 PM

I generally like to use one of these on the cigarette lighter fuse

Capture.jpg

**Tombie** · 1st January 2024, 09:58 AM

Originally Posted by haydent

the flip side of this is that if you manually have to turn your radio on/off every time you drive the car you end up leaving it off plenty of times and potentially miss things, so i wire to acc, the noise thing is a furphy with modern uhf, maybe in the 27mhz am cb days...

Whilst the NR on modern UHFs is very good as noted, using direct to battery connection provides a fantastic filter which reduces the induced noise and improves performance.

This line noise can be notably measured using an oscilloscope when using alternative feed sources. Especially in electronically controlled engines which produce significant RF when running.

And I wouldn’t worry about leaving a UHF on, they draw minuscule amounts on standby. The UHFs (2) are both on 24/7 in my D4 - I can’t be bothered turning them off.

**DieselLSE** · 1st January 2024, 10:14 AM

Originally Posted by Tombie

The UHFs (2) are both on 24/7 in my D4

Do you have conversations with yourself?

**RANDLOVER** · 1st January 2024, 05:57 PM

Originally Posted by DieselLSE

Do you have conversations with yourself?

Good to have one UHF for monitoring/scanning channels and one to talk on, or in Tombie's case an extra one to get passengers involved in sing-a-longs, especially duets.

**Tombie** · 1st January 2024, 06:33 PM

Both are commercial units, programmed with the usual 80 plus a plethora of registered channels.

I can actively use both in that capacity.

On long trips, one is on the talk channel the other is scanning and monitoring.

We use the Commercial handhelds for the singalongs

**DieselLSE** · 1st January 2024, 07:57 PM

Originally Posted by Tombie

Both are commercial units, programmed with the usual 80 plus a plethora of registered channels.

I can actively use both in that capacity.

On long trips, one is on the talk channel the other is scanning and monitoring.

We use the Commercial handhelds for the singalongs

I've never been into CB stuff as I usually travel with just one vehicle, so I've just carried GME 5W handhelds. But after the Simpson trip I can see the advantage of a vehicle mounted unit and I will get one for my next trip later this year. But I thought there was a way to scan all channels but only talk on one. Do I really need to install two units?

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