'99 Merc 115. Yellow stator wires fried.

[whackit]

Hi Folks,
First post from a long time lurker. Trying to figure out what's up with this situation. The two yellow wires from the stator to the regulator are corroded and burnt to the point that they are split. Here's the weird thing. Boat has been running/charging fine for the last season with this condition. We don't currently run any accessories beyond a bilge pump wired directly to the battery. So what should my plan be with this? We are going to restore a bunch of the boat this summer and get it all working again (gauges etc). I'm good with electrics but boat is in storage and can't get to it for the next month or two to meter everything. Note the red wires just look fried by proximity to yellow ones.

 

[boscoe99]

Corrosion increases electrical resistance. Increased electrical resistance results in temperature. The corroded connection points go so hot they melted the wire.

Cut the existing bullet connectors and splice new ones in. Then include inspecting the connections periodically as part of your maintenance plan.

Some folks will hard wire the splices so there are no connection points to corrode and fail.

 

[merc850]

Don't use the motor to charge a dead/low voltage battery; charge the battery to full with a charger and a deep cycle battery is not recommended, just a marine starter one.

 

[boscoe99]

Don't use the motor to charge a dead/low voltage battery; charge the battery to full with a charger and a deep cycle battery is not recommended, just a marine starter one.

Why not?

 

[Texasmark]

Why not?

Because the engine mounted charging is to keep a charged battery charged during engine operation and battery drain. Always check your battery prior to usage when boat is seldom used and charge with a power line powered charged to get the battery 90-100% full. Otherwise you could have fried wires....if not caused by other listed causes while attempting to charge a discharged battery. Wondering how you got the engine running to burn up your charging system wiring if the battery was that discharged?

 

[merc850]

My sister had a dead battery in her seadoo and she had someone boost it at the ramp; burned out the stator and part of the ignition system. Boosting is also bad news.

 

[boscoe99]

The electrical generation system is designed to output X amps. Does not matter if those amps are flowing to a battery that needs to be charged or to any other devices that consume electrical power. The rectifier/regulator knows not to where those amps go.

 

[harmanoff]

Ive never had any issues with a deep cycle marine battery. I also use a solar powered maintainer on my boat tho as well so the battery is always topped off for each weekend of use, as it sits all week in the water.

 

[Texasmark]

The electrical generation system is designed to output X amps. Does not matter if those amps are flowing to a battery that needs to be charged or to any other devices that consume electrical power. The rectifier/regulator knows not to where those amps go.

The service manual states otherwise! Besides, seldom do normal requirements require the full 16 amps for an extended period of time to maintain a charged battery, if amperage ever gets that high with maintenance charging.....I doubt it! Add connector corrosion to trying to charge a discharged battery and you have a recipe for disaster!

 

[boscoe99]

The corrosion was the problem. Not the current flow that was trying to get across a defective connection point.

Five amps trying to cross a defective connection causes more damage than 15 amps flowing across a good connector.

I suspect the R/R is just fine. Cut out the corroded points, hard wire or install new terminals and you will be good to go.

 

[merc850]

Those corrode yellow wires look like they're from the rectifier and the connections should be replaced,the red ones could be from the regulator.
At the right below the starter is another burned connector which looks like it's from the rectifier, it should be fixed too.

 

[Texasmark]

The corrosion was the problem. Not the current flow that was trying to get across a defective connection point.

Five amps trying to cross a defective connection causes more damage than 15 amps flowing across a good connector.

I suspect the R/R is just fine. Cut out the corroded points, hard wire or install new terminals and you will be good to go.

Simply Ohm's law: Power dissipated equals current squared x resistance. if resistance is zero, zero squared is still zero and power dissipated (heat) is also zero. Since power is a second order equation the dissipation rises logarithmetically...{exponentially) as the resistance is increased linearly.

 

[flyingscott]

Well the fallacy of not charging a dead battery with your motor is BS. I have seen that happen on Mercs before replace all the connectors then test the charging system.

 

[boscoe99]

Boats being used infrequently as they are, with lead acid batteries losing some electrical power (voltage) over time, it is quite common for an outboard motor to be started with either a partially depleted battery or a somewhat depleted battery. Some get lucky where a battery barely has the power to turn the motor over a time or two but the motor then starts and runs just fine. In which case the electrical generation system has to provide current to charge the battery. Perhaps maximum current for a period of time. No harm no foul if the electrical wires and connectors are in good working order.