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[N1RRA]

Everyone is always talking about getting power from the battery.  So, what about another always on source of power for a 2m rig that is much closer to the usual operator's position?

Like the power for the adjustable seat?  Tell me why not before I wire it up. Makes sense to me.

[AA4PB]

Is the wire size and fuse size suitable to provide the current needed by the electric seat plus the current needed by the radio during transmit?

[KF5LJW]

You are on the right track, just need a little guidance. The worse mistake you can make is taking the radio battery negative to the battery term post. You want the negative lead as short as possible, and that is where Seat Power comes into play or a seat bolt. Auto manufactures place Ground Terminals under seats, especially trucks. They are placed there for high-current accessories. Example most have options for sub-woofers and Audio amps, inverters, plus power/heated seats, and windows. If you cannot find one use a seat bolt.

However you want to take the positive directly to the battery terminals for power. You want a dedicated circuit not sharing with anything. If you take power from the accessories plug, you are daisy-chained and will share power with another device. You do not want to do that as that invites noise into your radio circuits. Exact same reason you never want to take negative to the battery. If you do will run vehicle current through your radio every time as there is no avoiding it because you are in parallel with the vehicle wiring.

Best practice is terminate radio negative as close to radio as possible on vehicle chassis or Ground Terminal hard-point. Do not use a fuse on negative. Run radio positive directly to battery term post placing fuse as close to possible to battery terminal. Do not roll up slack, cut to length.

[W9WQA]

since you will not be using the power seat constantly !, probably never,id use that for a 50 w or less radio.
good idea...
oh, seat bolt is great ground...

[WB6BYU]

That assumes that the wire size is rated for the
required current at the higher duty cycle of a
ham radio compared to a seat adjuster.

The seat motor probably will still operate at
10V under load, while your radio may lock
into transmit mode when the supply voltage
drops (had that happen to me with two radios:
in one case, the radio locked up at 50W, but
not up at 25 W with the engine running,
to voltage drop in the wiring.  But when my
wife turned off the engine while transmitting
at 25W, it locked up, she locked the car, and
went off to her appointment.  Took me about
half an hour to get there, find the car, unlock
it, and shut off the radio...

So even if the fuse is big enough, you may
find that the voltage drop through the
wiring harness is more than the radio can
handle at full power.  You won’t know until
you try it.

[W9FIB]

Also use a snubbing diode. Seat motors are very noisy and love to make voltage spikes that could damage a radio. Better to be safe than sorry on that.

[N1RRA]

I knew it would work, just was unsure of consequences, which was why I asked.
Thanks so much for the insights! and answers.
Keep em comin......I am not done yet!

[W9WQA]

i moved my seat back a few yrs ago.

[W1MOW]

For curiosity sake, I went out and looked at the seat motor wire size in my 2019 F-150. Looks to me to be either an 16 or 18 awg. I was not able to read and markings, tried to take a picture with my phone, but that was no help.

While sounding like a novel idea, I think, and I maybe wrong, that he wire is too small to power a 50 watt VHF/UHF radio. The other thought I had was, how many connectors does it go through, and how much power will they handle.

Let us know how you made out.

Gary W1MOW

[N1RRA]

OK, so after this, I will run a dedicated wire, with fuse, to the pos of the battery for power and ground under the seat, with a short wire.
Is 14 awg sufficient for these? I see that's what some power cables on eBay are made of.
Thank you all for your input!

[N1RRA]

There is a lot of info here:  http://www.k0bg.com/wiring.htmlhttp://www.k0bg.com/wiring.html

[K6BSU]

Can't imagine anyone so lazy that they have to use a seat motor to operate the seat.  My humble Toyota has a couple levers that move the seat around.  They are quite easy to use.  One more motor means one more failure point, someday./

[W9FIB]

Can't imagine anyone so lazy that they have to use a seat motor to operate the seat.  My humble Toyota has a couple levers that move the seat around.  They are quite easy to use.  One more motor means one more failure point, someday./

Guess I am lazy then. Electric seat position motor, backrest position motor, lumbar support motor, heating elements to keep me warm in winter, and speakers in the head rest. Gotta love it!

So you don't need to imagine anymore.

[K0UA]

In all of the cars and trucks I have ever owned, and I have owned a bunch, I have never had a failure of a seat motor. I have had the failure of the manual seat mechanism in a couple of vehicles. So I am thinking seat motors might just be more reliable.    In any case seat motors sure don't fail very often do they?

[KU3X]

...............The worse mistake you can make is taking the radio battery negative to the battery term post. You want the negative lead as short as possible...........

Why do you say that? I've been running mobile HF at 100 watts out for over 40 years and not only never had an issue, but also always got my 100 watts out. I make sure I do not skimp on wire size. On my Honda Accord I use #10 wire to my TS 480 SAT......full power out....works great.
I've wired both leads direct to the battery 100% of the time.

Barry, KU3X