Electrical Mystery - Help!

[Trophy]

Gauges show starting battery 12.5v, house battery 12.4v (both older), main and kicker start ok, gauges ok, down riggers ok. Problem.....Sounder wouldn’t turn on this a.m.
Started testing with multimeter at home and found matching 12.5/12.4 volts at fuse bar direct from batteries.
Checked wire voltage at sounder fuse 12.2 v. No brunt fuses in bar, checked voltage at end of sounder power plug 12.2 v. While in cuddy found that the 2 cuddy lights won’t turn on and vhf radio will turn on/light up for a split second then die!!!! Note: The vhf was working while on the water and main running.
Could fuse bar be the issue? Any experience or testing of bar?
Batteries toast? Could a power drop upon startup cause sounder/vhf not to run?? I remember dealer saying 14 volts recommended at panel to start main. Also recommended a 1000 mca for starting battery (is). Volts on main were usually around 14.4v but now 12.5v yet main started no problem. Charged both batteries a few weeks ago.
Any ldeas?
Thanks!

 

[gungadin]

It sounds like you have a poor connection somewhere. Yes it could be the fuse bar, but I would check connections first.When checking the voltage at your sounder you need to use the same ground that the sounder uses, same withe VHF and lights. Going from the battery power from the fuse panel at the sounder but using a ground other the ground you used for the sounder could give you an incorrect reading as it is not measuring the resistance in the actual wires being used. If you are already doing this then disconnect the wiring for the sounder at the fuse and ground bars and connect them to the battery directly with jumper wires, perhaps through an inline fuse in the positive lead. If the Sounder works fine then you know the wiring from the fuse panel to the sounder and back to the ground bar are fine. This would indicate a problem in the fuse or ground bar.Repeat with radio and lights.

 

[Ringo]

I had a similar issue with the sounder on my previous boat. I cleaned the corrosion on the battery connections and also put some dielectric grease on my sounder sockets and it was all Ok after that.

 

[outbeen]

Bad wiring somewhere probably as a result of corrosion. Theres still enough wire left for the gauge to work, but under any type of load it just fails. Test for resistance on the 2 main leads from your battery to the fuse bar, as it appears that the issue is affecting multiple systems. Good luck!

 

[Viking]

I would try a long wire and jump power and ground to the dead circuits. One or the other. Good luck.

 

[CIVANO]

What do the items not working have in common? all to same positive or probably negative buss?

 

[TheHurtLocker]

Sounds like a bad neutral connection.

 

[sudsy]

Bad ground or connection broke somewhere

 

[ryanb]

12.6v is a fully charged battery. You do not need 14v to start your main as the battery will never have that voltage except when it is being charged. Your batteries are likely not the issue for sure.

Even at 12.2v there should be zero issues running any electronics.

 

[sir-vivor]

Call Moose in Nanaimo , he can figure it out for ya in a second lol . Can't find his number but maybe somebody could chime in with his contact number. I Had a problem no one no in the lower mainland could figure out (or cared to help) and over the phone Moose got er done ! Knows his electronics !!

 

[Trophy]

Update:
Followed some of your suggestions, ran direct lines from battery to sounder, vhf, ....units turned on no problem!
Focused on 20 + year old fuse bus and fuses again, clean no corrosion. Started to pry connections from plastic housing and found some corrosion hidden under plastic..... Possible cause, good reason to replace. New fuse bus on its way. Project on the to do list anyway. Truly believe this was the cause.
Many thanks for your advice and assistance!