Before I go Re wiring things

[fish brain]

I'm looking for some advice
I run a couple of older Lowrance LCX112 plotters. I was going over the boat before a trip to Bamfield next week, and when I fired up my plotters one shut down after about a minute. I switched out the head for my spare thinking it was the head. I fired everything back up and the other one shut down. Realizing the head was not the problem I set them to give me a voltage reading. The voltage at the heads is fluctuating from 12 to 8 volts. I used my meeter to confirm this. with no units on there is a steady 12 volts,as soon as I turn one on it drops to 10 volts and down to 8 volts when I turn on the second one. I have a no 10 wire feeding the sub panel in my roof. all the connections are clean and tight. It happens on both batteries which are hooked to a charger. It has never done this before.
Does anyone have any idea why this would happen? I am about to run a new wire from the night switch to the sub panel. Is there anything obvious I should check first?

 

[Brando]

Get the batteries load tested and check voltage at the night switch try checking the voltage with your engines running.

 

[Foxsea]

I'm looking for some advice
I run a couple of older Lowrance LCX112 plotters. I was going over the boat before a trip to Bamfield next week, and when I fired up my plotters one shut down after about a minute. I switched out the head for my spare thinking it was the head. I fired everything back up and the other one shut down. Realizing the head was not the problem I set them to give me a voltage reading. The voltage at the heads is fluctuating from 12 to 8 volts. I used my meeter to confirm this. with no units on there is a steady 12 volts,as soon as I turn one on it drops to 10 volts and down to 8 volts when I turn on the second one. I have a no 10 wire feeding the sub panel in my roof. all the connections are clean and tight. It happens on both batteries which are hooked to a charger. It has never done this before.
Does anyone have any idea why this would happen? I am about to run a new wire from the night switch to the sub panel. Is there anything obvious I should check first?

You have a poor connection somewhere. Even if the terminals are clean and tight there can be corrosion in the crimp or fatigue with poor conductivity. I got tired of gremlins and have redone most helm wiring. Use Ancor wire, Blue Seas panels or Carling switches and quality shrink terminals with a good quality, rachet crimper. Use NoOxId or similar grease (not silicone grease!) on the wire before crimping. Test every crimp before shrinking. Restrain the wire to dampen vibration.

Boat wiring is very susceptible to fretting corrosion, caused by vibration.

 

[brutus]

I'm looking for some advice
I run a couple of older Lowrance LCX112 plotters. I was going over the boat before a trip to Bamfield next week, and when I fired up my plotters one shut down after about a minute. I switched out the head for my spare thinking it was the head. I fired everything back up and the other one shut down. Realizing the head was not the problem I set them to give me a voltage reading. The voltage at the heads is fluctuating from 12 to 8 volts. I used my meeter to confirm this. with no units on there is a steady 12 volts,as soon as I turn one on it drops to 10 volts and down to 8 volts when I turn on the second one. I have a no 10 wire feeding the sub panel in my roof. all the connections are clean and tight. It happens on both batteries which are hooked to a charger. It has never done this before.
Does anyone have any idea why this would happen? I am about to run a new wire from the night switch to the sub panel. Is there anything obvious I should check first?

Just bypass all your wiring by going from your batterie to your head unit with nothing in between, if it works fine, then start chasing the gremlins lol, might be the green death in your wires

 

[fish brain]

@Foxsea nailed it! There was a bad ground.
Someone used a spade connector on a #10 wire. I pulled it off and crimped a round connector on and bolted it to the ground post under the helm, and wahla! 12.5 volts when everything on the circuit was turned on.
Thanks for your input everyone.

 

[wildthing]

boat electrics 9 out of 10 its a bad earth normal copper not tinned. and corrosion in the crimp connection .....

 

[Foxsea]

boat electrics 9 out of 10 its a bad earth normal copper not tinned. and corrosion in the crimp connection .....

"earth"? I believe Canadians speak English but the Brits have different words for so many things. My favorites are the car terms like bonnet and boot.

 

[wildthing]

Ding dong low blow.....lol
her indoors is going to be rather miffed say by joe that deffo not cricket.....
tally hoe .........