Lights dim when keying mic on VHF

[deerhuntre]

Is it normal for the running lights and dome lights to dim on the boat while keying the mic on my VHF while using the 25 watt setting?

I'm thinking this is probably not normal and maybe I need to run a larger gauge wire from the battery to the fuse panel?

 

[freddyray21]

Re: Lights dim when keying mic on VHF

25 watts can draw some current. It might dim the lights if the alternator is not running and you have a weak battery.

 

[deerhuntre]

Re: Lights dim when keying mic on VHF

The alternator was not running at the time, but last year I used to troll off the main motor and the lights still dimmed, so in the past I was running with the alternator going and still had the issue. Could it still be weak batteries?

 

[joed]

Re: Lights dim when keying mic on VHF

Dimming lights indicates a voltage drop. It could be weak battery or wiring too small a guage. You could test it by measuring the voltage at the battery and at the fuse panel.

 

[deerhuntre]

Re: Lights dim when keying mic on VHF

Thanks for the suggestion. I was thinking about running a thicker wire from the battery to the fuse panel, but first I'll test the voltage and make sure the existing connections are ok.

 

[DRIFTER_016]

Re: Lights dim when keying mic on VHF

I just replaced the main accessory power wire run in my boat because of similar issues. The factory power and ground wires that were run from the battery to the console were only 14 or 16 guage and were also starting to corode. I could have gotten away with 10 guage as replacement but was only able to purchase 8 guage here in town. I now have no power drain problems and all is good.

 

[deerhuntre]

Re: Lights dim when keying mic on VHF

I think that's what I'll do; run thicker wire from the battery to the main fuse panel. Both the hot and ground, of course.

In the mean time, I also was told I was not able to be understood on the radio and I called Uniden who had me send them the radio for warranty service. So, now I'm curious to see what their report is as well.

I'll let you guys know the outcome.

 

[joed]

Re: Lights dim when keying mic on VHF

The low voltage could have been the problem with the radio as well. It could have caused distortion and garbled sounding transmissions. I also had water in the mic do this my radio once.

 

[Boatist]

Re: Lights dim when keying mic on VHF

Low voltage from wires too small can sure make the radio have problems. When you get the radio back if you have not yet changed the wires then try the radio in one watt mode and see how it sounds. If it is a voltage problem should sound good in 1 watt mode.

Make sure your fuse the new Positive wire with the proper size fuse. 30 amps for 10 Guage. 20 amps for 12 guage.

 

[zibzer]

Re: Lights dim when keying mic on VHF

What size wire are you currently running to the fuse panel?

and what other accesories are running at the time?

 

[deerhuntre]

Re: Lights dim when keying mic on VHF

I did some investigation and made a few changes. Here is what I found:

1. The positive and negative wires running from the battery to the fuse panel are 10 gauge. The branch circuits are 14 gauge.

2. I found loose ground screws on the ground panel.

3. There is a daisy chain connecting each branch on the fuse panel. The starboard-most side is where the battery connection is and the port-most side is where the radio was connected.

4. The daisy chain has crimped-on connectors that appear old and a bit coated with chalk-like matter. The copper strands of the wire in the daisy chain appear dark.

So, here's what I did so far:

I made a new daisy chain using the same 14 gauge wire with new crimp-on connectors.

I also made a new daisy chain and used new connectors for the ground panel.

I cut off an inch or so on the positive 10 gauge and negative and crimped on new connectors.

I moved the radio connection to the starboard-most connection so it's closet to the battery lead connection.

Status: The radio is still at Uniden being serviced pursuant to their warranty coverage and once I get it back, I'll install and try it out. If I still get the dimming lights, I'll then perform a voltage drop test.

Please let me know if the 10 gauge is not sufficient or if the 14 gauge is too small to power the fuse panel.

Could the corroded connectors and the loose ground be the cause?

 

[Boatist]

Re: Lights dim when keying mic on VHF

10 guage is fine for the Radio. I would take your ground wire all the way to the 10 guage ground wire from the battery. This assumes your not running anything that draws a lot of power on this same 10 guage wire.
Any thing that has any white chalk is not making a good connection.

14 Guage should also be fine for the radio it self if the run is not too long. Most radios draw about 5 amps max and a 14 guage wire can cary 15 amps.

 

[deerhuntre]

Re: Lights dim when keying mic on VHF

By the way, here's a list of items connected to the fuse panel that I'm using:

Running lights
60 watt headlight, incandescent.
Lawrence GPS/Sonar unit
Bilge pump on switch wired to fuse panel
Second bilge pump fused and wired directly to battery
Livewell pump

 

[deerhuntre]

OK, here's the results

OK, here's the results

I received my radio back from Uniden today and they replaced the microphone.

In the boat, I replaced all the ends on the fuse panel as described above and today I also replaced the ends on the battery side.

I hooked up the radio and keyed the mic with the lights on. The lights did dim, but much, much less than before. The motor was off during the trial and I was only operating off of the battery. Under the 'lo' setting, the lights did not dim at all. Tomorrow I plan to take the boat out and will find out how it sounds on the other end.

So, I'm thinking that a slight dimming may be normal/ok?

 

[deerhuntre]

Re: Lights dim when keying mic on VHF

Radio check was 'loud and clear'. With the motor running, there was NO DIMMING!!!

I think I'm all set!

 

[Boatist]

Re: Lights dim when keying mic on VHF

Glad to here your got it up and running.
Always good to have a good working radio.