Ground Cable

[Waytam]

I have a mercruiser 5.0 and have been fighting a voltage drop when I engauge the trim/tilt. I have two batteries with a battery swith. If I have the switch on battery one which has the ground wire running to the block i get a voltage drop that causes some of the gauges to stop working and the radio to cut out when the trim is engauged. If i have the battery switch in the All position or on battery two the problem goes away. I dont see any corrosion on the cable. The boat will start on battery one with with no problems but I do get the voltage drop when the trim is engauged. Is it possiable for the cable to be bad but still aallow the boat to start ?

 

[Don S]

Re: Ground Cable

Clean BOTH ends of ALL cables, positive and negative, and reattach. Make sure they are all tight with a wrench (Throw away the wingnuts and use regular nuts). Make sure the ends of the cable going into the terminals are also tight and clean. If they are loose or corroded replace them.

 

[Waytam]

Re: Ground Cable

I am using standard SS nuts. The cable ends are tight and dont appear corroded.

 

[Augie56]

Re: Ground Cable

I just had this same problem this spring. The PO ran my boat with one battery, and I wanted dual batteries, so I bought two new batteries and picked up a used Perko 2-both-1-off with enough extra battery cables off of Craigslist. I installed everything per directions for my switch (downloaded off Perko's website), and created the same problem you have.

Turned out that boat battery cables are VERY sensitive to corrosion and added resistance on the connetions. What looks like minor, greenish-colored corrosion will actually drop enough of the voltage to cut your engine coil when you try to run the trim. Like Don S said, EVERYTHING NEEDS TO be corrosion-free before assembly (wire-wheeled, sand paper, wire brush, whatever). Also, if you have a multimeter, you can check all your cables end-to-end to verify good continuity and minimal resistance. I think my cables ohmed out at just a couples of ohms each after I found the problem (one of my cables initially ohmed out at around 230 ohms...not good).

Are both your batteries good? I also read that one bad battery could drag down the entire system enough to cause problems (with the swtich in the BOTH position).

Good luck.

 

[Bondo]

Re: Ground Cable

I am using standard SS nuts. The cable ends are tight and dont appear corroded.

Ayuh,.... "Appears" is irrelevant,....

Pull 'em apart, sand, 'n clean to Shiny metal, 'n reinstall...

 

[texamwalker]

Re: Ground Cable

Everybody seems to be blaming corroded cables or bad connections. I know that this is typically the problem and a likely place to check first, but if im reading this correctly, hes saying that the voltage drop occurs when the tilt/trim is engaged. If the cables are clean and tight like he said, and both batteries are good......would i be wrong to assume that a bad winding in tilt/trim motor could be the problem??
Ive seen those motors start to go bad, and while they still work, they will draw an excessive amount of amps.

 

[Bondo]

Re: Ground Cable

Everybody seems to be blaming corroded cables or bad connections. I know that this is typically the problem and a likely place to check first, but if im reading this correctly, hes saying that the voltage drop occurs when the tilt/trim is engaged. If the cables are clean and tight like he said, and both batteries are good......would i be wrong to assume that a bad winding in tilt/trim motor could be the problem??
Ive seen those motors start to go bad, and while they still work, they will draw an excessive amount of amps.

Ayuh,... I don't think switchin' batteries would change things, if that were the case...

 

[texamwalker]

Re: Ground Cable

youre right... i mis read what he originally said. the last thing i would check would be the switch itself. i know they are supposed to be sealed but im sure its possible to break and allow water to corrode the inside. a quick check with the ohm meter should determine whatever problem he has.