Mobile Grounding

[M0GVZ]

You apparently do not live in the 'rust belt'..!

Hasn't America discovered zinc coating and other anti-corrosion techniques?

When I wire vehicles, I make sure to connect the negative lead from the battery to the engine block near the starter

Yet I've not had a car where the manufacturer has done that for decades. You Americans sure have some really poorly built cars.

[KA9JLM]

So you've just electrically bypassed the 0V line fuse....

True that.

Fuses are made for Faults and anything may / could happen.

Many Yaesu mobile radios fuse both + and - DC connections for safety.

[OSIRIS]

Does anyone bother to RTFM?

The Yaesu FT-8800R Operating Manual clearly states:
Mobile Power Connections
To minimize voltage drop and avoid blowing the vehicle’s fuses, connect the supplied DC
power cable directly to the battery terminals. Do not attempt to defeat or bypass the DC
cable’s fuse – it is there to protect you, your transceiver, and your vehicle’s electrical
system.
Connect the RED power cable lead to the POSITIVE (+) battery terminal, and the BLACK
power cable lead to the NEGATIVE (–) terminal. If you need to extend the power cable,
use #12 AWG or larger insulated, stranded copper wire. Solder the splice connections
carefully, and wrap the connections thoroughly with insulating electrical tape.


Here's a snap from the ICOM IC-V8000 manual which shows how to wire the radio directly to the battery.
connect.png

[KA9JLM]

Does anyone bother to RTFM?

The Yaesu FT-8800R Operating Manual clearly states:
Mobile Power Connections
To minimize voltage drop and avoid blowing the vehicle’s fuses, connect the supplied DC
power cable directly to the battery terminals. Do not attempt to defeat or bypass the DC
cable’s fuse – it is there to protect you, your transceiver, and your vehicle’s electrical
system.
Connect the RED power cable lead to the POSITIVE (+) battery terminal, and the BLACK
power cable lead to the NEGATIVE (–) terminal. If you need to extend the power cable,
use #12 AWG or larger insulated, stranded copper wire. Solder the splice connections
carefully, and wrap the connections thoroughly with insulating electrical tape.


Here's a snap from the ICOM IC-V8000 manual which shows how to wire the radio directly to the battery.
connect.png

Looks like the correct way to me.

The case of the radio should be grounded for your RF ground.

Or should it ?

[K0BG]

That is the correct way, but as I said before, you have to be careful nowadays. And for the reasons I stated. As an adjunct to these reasons, most vehicle manufacturers are switching over to AGM rather than flooded designs, and placing the batteries someplace other than the engine compartment. This requires the use of jump points, wherever they may be located. All of this is driven by the efforts to reduce emissions, and increasing fuel economy.

[KB4QAA]

Not much point in grounding the chassis of a 2m rig.

[K9STH]

QAA:

The truth be known, I have run into several 2-meter FM rigs that had all sorts of r.f. problems until the chassis was grounded! Mainly, r.f. getting into the transmit audio circuits.

Glen, K9STH

[M0GVZ]

Does anyone bother to RTFM?

Here's a better idea.

Get a multimeter. Set it to continuity. Put one probe on the end of the black cable and the other probe touch anywhere at all you would like on the metal case of the radio.

Report your findings. I think you'll find that it shows there is continuity. So what do you think happens when you connect a ground strap from the body of the car to the radio ground screw?

As for voltage drop, compared with connecting both cables to the battery and only connecting the red with the black to a ground point on the car body near the radio I did that once before upgrading the power feeder cables when I fitted a TS480HX. I measured a 0.1V difference.

[M0GVZ]

QAA:

The truth be known, I have run into several 2-meter FM rigs that had all sorts of r.f. problems until the chassis was grounded! Mainly, r.f. getting into the transmit audio circuits.

Glen, K9STH

Maybe they should've installed their antennas properly.

[KF5LJW]

What you need to do here, is follow the manufacturer's recommendations. That is directly to the battery, or jump point, and not use the body of the vehicle.

I agree 100%. old outdated habits are hard to break. Smoking and deep fried food use to be popular and cool.