Author Topic: Car instalation power wiring selection?  (Read 868 times)

Offline Greekman

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Car instalation power wiring selection?
« on: April 08, 2019, 03:07:12 PM »
I am about to run a length of power wire from the bsttery to the car interior for my mobile.  Thing is that i am perplexed with ehat others have told me.
A DC wire calculator tells me that for 10 feet of wire,  15 amps of current and an expected loss of 5% i need 4mm thick wire. 6mm for 3% loss.

But in a Greek HAM page i got the advice that 2.5mm thick cable is alright and generally voltage loss is not taken into consideration under 10 meters.
Huh?

Offline Smurf Hunter

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Re: Car instalation power wiring selection?
« Reply #1 on: April 08, 2019, 04:17:41 PM »
I am about to run a length of power wire from the bsttery to the car interior for my mobile.  Thing is that i am perplexed with ehat others have told me.
A DC wire calculator tells me that for 10 feet of wire,  15 amps of current and an expected loss of 5% i need 4mm thick wire. 6mm for 3% loss.

But in a Greek HAM page i got the advice that 2.5mm thick cable is alright and generally voltage loss is not taken into consideration under 10 meters.
Huh?

The greek ham page sounds right to me.

In the USA, we commonly use 12 AWG (gauge) wire for up to 30 amps.  That's about 2mm thick.  Yes, you will suffer voltage drop over long range, but I have to think you'll use much less than 10 meters to reach your interior radio from the battery.

Definitely go larger/thicker/better as your budget allows, but for most mobile radios that have 50 watts, you will only be drawing 10 amps or less.
I use 12AWG for 100 watt HF radios without problems.

Offline armymars

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Re: Car instalation power wiring selection?
« Reply #2 on: April 08, 2019, 04:58:01 PM »
Making sure the wire has a low loss connection to the radio is just as important. 

Offline exSun

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Re: Car instalation power wiring selection?
« Reply #3 on: May 07, 2019, 10:23:57 AM »
Whatever wire you use, fuse both the positive and negative wires as close as possible to the battery. I once saw a steel tie down rod that had fallen across the battery terminals in a car. The wrench was red hot and had burned a hole in the battery case. The battery was giving off hydrogen gas, which had ignited. The blue flame at night was a pretty sight, but it was our ride home ... not good. So - put a proper size fuse in any wires you add!

Offline Greekman

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Re: Car instalation power wiring selection?
« Reply #4 on: May 07, 2019, 12:07:53 PM »
Whatever wire you use, fuse both the positive and negative wires as close as possible to the battery. I once saw a steel tie down rod that had fallen across the battery terminals in a car. The wrench was red hot and had burned a hole in the battery case. The battery was giving off hydrogen gas, which had ignited. The blue flame at night was a pretty sight, but it was our ride home ... not good. So - put a proper size fuse in any wires you add!

that reminded me that I haven't ordered the fuse holder/cables yet  :(

Making sure the wire has a low loss connection to the radio is just as important.

my battery leads have enough thread to screw a ring terminal on them. think this will be OK