Electrical Gremlin - any tips or suggestions

[Trophy]

vhf radio turns on then dies, no cuddy lights, no horn, lights, wipers, etc which are all connected to dash switch panel or direct to dash fuse panel. Anything wired directly to batteries with in line fuses like down riggers, kicker steering etc are ok. Guages/helm shift/starter/ big motor wired separately new 3 yrs ago with new motor - all ok. Use #1 battery to start/run big motor, battery #2 while trolling. Charged both batteries, #1 starting battery 12.7, #2 deep cycle battery 12.5. Battery #2 on - Tested vhf radio at radio 12.5, at fuse panel 12.5 without fuse 0, fuse panel itself 12.5. Same results with battery #1. Tested fuses in panel and any in line, all tested good.
Any ideas where to check next are appreciated?

 

[fishin solo]

Sounds like wire to your dash switch panel may have a short somewhere

 

[Franko Manini]

I'm going with a bad ground. Replace all the ground wires/connections. If you're not using tinned marine grade wire, often you will get corrosion between the crimp on connector and the wire and this will cause resistance. It might be just one connector, but my guess is that is is several. The effect is additive.

As a quick test, you can run a jumper wire between the radio ground wire and the battery's negative terminal. If things work as suspected, then start looking for a crappy ground relative to your fuse panel.

 

[Alex_c]

Yup sounds like a bad connection to your buss bar or dash switch panel. Check for corrosion and loose connections, then start looking at ground wires.

 

[Trophy]

Thanks guys....good tips. I'll run a direct ground from battery to radio also to fuse panel/switchs tomorrow and see if I can isolate it that way. Makes sense to replace all old with proper marine wire for sure.

 

[ericl]

FYI those battery voltages are low; they should be 13.5 or more. This indicates bad batteries. Try placing a load on the deep cycle then measure the voltage.
How many ground wires from the fuse panel to the battery?

 

[CIVANO]

13.5 or more only when being charged!

 

[Old Fisher]

FYI those battery voltages are low; they should be 13.5 or more. This indicates bad batteries. Try placing a load on the deep cycle then measure the voltage.
How many ground wires from the fuse panel to the battery?

A fully charged 12 volt battery should carry 12.6-12.7 V
Voltages of more than that are normally seen only when charging the battery.

 

[profisher]

Around the salt most likely a green wire from corrosion. I'll bet a pin hole in the outer jacket of the positive or negative to the dash and the copper has gone green and the resistance is causing your symptoms.

 

[Trophy]

Bingo!
Found a unkown corroded inline fuse coming off the battery switch deep in the hull. Cleaned and replaced fuse - everything works again.
Many thanks for your suggestions, new wiring added on the to do list.

 

[CIVANO]

use tinned marine grade wire

 

[spring fever]

12.6 to 12.7 volts is a fully charged static state of a good 12 volt battery. You will only see higher when being charged-anywhere from 13.5 to 14.6 volts. Just another bit of info to tuck away!! LOL