Mobile Install Question

[W4XED]

I've searched and searched, but can't find the answer I'm looking for. I'm going to wire my quad band mobile ham in my 2016 Malibu Limited 1LT (which has an auxiliary battery in the trunk to facilitate restarts when the auto-stop engages). The only difference I can find functionally between the aux and the main battery is the CCA rating. It seems to me it would be easier to run the power from my rig to the aux battery instead of the main. Has anyone ever done this, and if so, did it work correctly; or if not, why? Appreciate any input.

73

John

 

[mmckenna]

My dad had a Malibu that had that. We installed a dual band radio in it. RF deck went under the package shelf in the trunk, tucked up out of the way. Power was run directly off that auxiliary battery. Control head up front on the console. Ground the negative lead to the body, not directly to the negative post on the battery.

That setup worked just fine, no RFI, nice clean power close to the radio.

Don't let the lower CCA rating concern you.


Also, most of our older Crown Victorias had an auxiliary battery in the trunk. All the radios, lighting, siren and computers fed off it. Used an isolator up at the main battery to keep things separate. That way it was always possible to start the car even if it had sat too long with the engine off and all the lights/radios running.

 

[Firekite]

Ground the negative lead to the body, not directly to the negative post on the battery.

Is this due to the battery health monitoring type stuff on some newer vehicles? On my 2011 F250 there is no such such, and I brought the 10ga marine positive and negative into the cab to the power distribution block and subsequently the radios, directly wired to the positive and negative of one of the batteries (both fused at the battery), with no problems cropping up so far. For what it’s worth, my original smaller wire was positive only and grounded to the chassis with no issues, either.

 

[mmckenna]

Is this due to the battery health monitoring type stuff on some newer vehicles? On my 2011 F250 there is no such such, and I brought the 10ga marine positive and negative into the cab to the power distribution block and subsequently the radios, directly wired to the positive and negative of one of the batteries (both fused at the battery), with no problems cropping up so far. For what it’s worth, my original smaller wire was positive only and grounded to the chassis with no issues, either.

Partially. On newer vehicles the manual will usually tell you NOT to connect to the negative terminal due to it creating a bypass of the Hall effect sensor. Since there would be a ground path from the antenna mount/radio mounting back through the radio chassis to the negative lead to the battery. It can not only throw it off due to the radio current draw, but can also result in not all the power being used caught by the sensor.

Using shorter negative leads to the body can help with RFI in some applications. On some commercial radios, it's recommended to use the body as the return path. Some larger radios (I had an old GE low band) only had a short negative lead with instructions to ground it to the body.
You want as short a run to ground as possible. No need to have the extra copper, extra terminations, additional wire length to absorb noise, etc.

But if yours works satisfactorily, then it's all good.

 

[BushDoctor]

Running a ground from your battery to ur radio is risky especially with GM equipment. one undercover automatic gm lost its ground and started grounding through the shift cable ruining the cable. Had the 2 way radio grounded direct to the battery without a fuse in the ground cable the grounded low band antenna could have been the starter ground through the radio when the shift cable could no longer handle the load. the cause was a bad connection at the engine to the body ground at the engine.