Mobile installation: Connecting transceiver to car battery

[fremont]

This topic has given me a headache.  A big one.

 

For example:

 

• Do you connect to both terminals?
• If so, do you run also connect to chassis ground?
• Do you fuse the negative connection?
• etc etc

 

I've looked online at as many ham mobile installation pages as I can, and I can't seem to find a consensus.

 

Help.  

[citizensoldier16]

I wired my mobile directly to the battery, both positive and negative. Positive has a fuse in-line. Haven’t had a problem.

[SteveC7010]

Many newer cars and light trucks now have power monitors on the negative terminal of the battery. Best practices these days are:

1. Hot to battery hot with an inline fuse within a few inches of the battery.

2. Negative to a factory grounding point somewhere in the vehicle.

3. Check the manufacturer’s install instructions. On commercial gear, fusing is not needed on the negative side.

4. Wiring going through the firewall must be appropriately grommeted. I use the large factory wiring grommet when possible. There’s usually plenty of room to run your power lines there without disturbing anything else.

5 Be neat use loom and ty-wraps.

 

I’ve done hundreds of commercial and public safety installs. These are the tried and true ways to do the job correctly.

[fremont]

Many newer cars and light trucks now have power monitors on the negative terminal of the battery. Best practices these days are:

1. Hot to battery hot with an inline fuse within a few inches of the battery.

2. Negative to a factory grounding point somewhere in the vehicle.

3. Check the manufacturer’s install instructions. On commercial gear, fusing is not needed on the negative side.

4. Wiring going through the firewall must be appropriately grommeted. I use the large factory wiring grommet when possible. There’s usually plenty of room to run your power lines there without disturbing anything else.

5 Be neat use loom and ty-wraps.

 

I’ve done hundreds of commercial and public safety installs. These are the tried and true ways to do the job correctly.

 

Steve, it sounds like you're close (if not exactly) on the same page with this post.  (His ELD and your power monitor are synonymous, I believe.)  My '18 Silverado has a voltage meter but I'm not sure if that's the same as the power monitor you mention.  I also don't see it on the negative cables that are heading towards my frame.

 

Unsure why, though, a wire goes from positive terminal to fuse box in the post's example below?

 

[WRFV510]

It says in my Motorola manual too to NOT ground direct to battery. My truck does have a power monitor but why cant it be direct to the battery? the monitor just gives a warning to start vehicle if the battery goes down too low so hooking the + direct to battery is going to do the same thing as far as the monitor is concerned. 

[berkinet]

...

Unsure why, though, a wire goes from positive terminal to fuse box in the post's example below?

...

Well, at times you might wish to listen to the radio, run the windshield wipers, turn on your headlights, and maybe even start the car

[Jones]

It says in my Motorola manual too to NOT ground direct to battery. My truck does have a power monitor but why cant it be direct to the battery? the monitor just gives a warning to start vehicle if the battery goes down too low so hooking the + direct to battery is going to do the same thing as far as the monitor is concerned. 

You don't want to hook your radio's negative direct to the battery, because your antenna is grounded to the body of the vehicle.  If the ground safety cutoff device fails, or cuts off for some reason, you don't want the rest of your vehicle finding ground through your radio back to the battery.

[fremont]

Well, at times you might wish to listen to the radio, run the windshield wipers, turn on your headlights, and maybe even start the car

LOL.  I assume that was an additional wire.  phew

[WRFV510]

looks like my ground goes to the starter and chassis so unless i unhooked the - terminal then hooked the radio back up id be good. but the better practice would be ground to chassis and eliminate the problem all together.  

[phottomatt]

Any one use one of these? Thinking of using it on my BTECH 50x1 GMRS.

BTECH Mobile and Amp DC Cigarette Cable

0 out of 5

[wayoverthere]

1 hour ago, phottomatt said:

Any one use one of these? Thinking of using it on my BTECH 50x1 GMRS.

BTECH Mobile and Amp DC Cigarette Cable

0 out of 5

I'd be cautious. First, those wires look a little thin, perhaps better suited to the 25 watt radios (hard to tell from the one pic, and no specs, though).  Second, check what your lighter plug will support in terms of current draw. It's not uncommon to see them fused at 10 or 15 amps;running high power, my 50x1 draws between 10 and 11 amps, which doesn't leave much (or any) room for other draws sharing the circuit with the lighter plug.