Mercury 60-HP BIGFOOT Not Charging
Posted: Mon Jun 27, 2022 12:13 pm
My boat has a [c.2006] Mercury 60-HP BIGFOOT engine. The charging system is no working.
in 2021 the engine stopped charging the battery. I found a fuse close to the Regulator Assembly was open and the fuse holder was melted. I replace the fuse (and holder) and Regulator Assembly having read that the Regulator Assembly was often cause of a blown fuse. I did not test the original regulator. I was new to small engine battery charging circuitry.
After this work, the battery voltage with the engine running would increase to 13.5-Volts from 12.75-Volts
I later took the boat for a week long trip to northern idaho. One day into the trip day I noticed that the boat would not accelerate to plane if more than one adult was aboard. After some testing, I found the engine was not charging the battery. Battery voltage decreased to 12.25 from 12.75 when the engine was started. The battery voltage became lower as the engine speed increases . The engine could be run, but eventually the battery charge would be drained and the volage would drop below 11.9-Volts.
I deduced the problem lack of engine power was due to the low battery voltage no creating sufficient fuel pressure.
Additionally, at this point the tachometer readings began to be erratic when the engine speed became greater than 2,000-RPM
I tested everything on the new regulator. I did all tests per the manual, including testing the supression diode, making resistance and diode tests of the regulator, and resistance test of the stator. The only test I did NOT do was the DVA test for the stator (supposed to be 19.5 amps at 5000 rpm). I don't have a DVA.
Fast forward one year to 2022. (I had access to another boat for the 2021 year so put this one away). I decided to be dumb and throw parts at it. I bought a new stator and regulator, since it is an old boat and at least I could rule those out. I tested it with the old ones, fired right up, behaved the same way EXCEPT now the tachometer maxes out to 6000 rpm the second the motor is running (turn key on, tach looks fine, start it up, tach pegs immediately).
I pulled off the flywheel. The magnets had come loose. They were attached to the stator. The magnets had come unglued. I pulled the flywheel off, and reglued magnets, carefully spacing them. One had broke in 3 pieces, but I just glued it in place with the others. (used JBWELD)
Put the flywheel back on. Same exact behavior. Changed out stator and regulator to new units. Still same behavior, in both the charging and the tachometer" the battery voltage drops to 12.4-Volts from 12.75-Volts, and the tachometer pegs on. I ran all tests again except DVA and I am getting measurements in all tolerances.
One other things: I have tested voltage at both the battery and the terminals at the engine. So I do not believe the battery is at play here (i.e. it is not generating the voltage necessary to charge)
Q1: Can magnets go bad?
There is clearance between the stator and everything seems fine so don't think my glue job was bad.
Q2: what else can play into the charging system here?
I feel like I missing something. I have tested all parts according to the Mercury troubleshooting. I have not done the DVA, but what would that tell me? I have put brand new parts on, so lets say it doesn't pass the DVA.
Q3: if all the parts are new and good, and diagnostic tests are good, what could cause this problem?
in 2021 the engine stopped charging the battery. I found a fuse close to the Regulator Assembly was open and the fuse holder was melted. I replace the fuse (and holder) and Regulator Assembly having read that the Regulator Assembly was often cause of a blown fuse. I did not test the original regulator. I was new to small engine battery charging circuitry.
After this work, the battery voltage with the engine running would increase to 13.5-Volts from 12.75-Volts
I later took the boat for a week long trip to northern idaho. One day into the trip day I noticed that the boat would not accelerate to plane if more than one adult was aboard. After some testing, I found the engine was not charging the battery. Battery voltage decreased to 12.25 from 12.75 when the engine was started. The battery voltage became lower as the engine speed increases . The engine could be run, but eventually the battery charge would be drained and the volage would drop below 11.9-Volts.
I deduced the problem lack of engine power was due to the low battery voltage no creating sufficient fuel pressure.
Additionally, at this point the tachometer readings began to be erratic when the engine speed became greater than 2,000-RPM
I tested everything on the new regulator. I did all tests per the manual, including testing the supression diode, making resistance and diode tests of the regulator, and resistance test of the stator. The only test I did NOT do was the DVA test for the stator (supposed to be 19.5 amps at 5000 rpm). I don't have a DVA.
Fast forward one year to 2022. (I had access to another boat for the 2021 year so put this one away). I decided to be dumb and throw parts at it. I bought a new stator and regulator, since it is an old boat and at least I could rule those out. I tested it with the old ones, fired right up, behaved the same way EXCEPT now the tachometer maxes out to 6000 rpm the second the motor is running (turn key on, tach looks fine, start it up, tach pegs immediately).
I pulled off the flywheel. The magnets had come loose. They were attached to the stator. The magnets had come unglued. I pulled the flywheel off, and reglued magnets, carefully spacing them. One had broke in 3 pieces, but I just glued it in place with the others. (used JBWELD)
Put the flywheel back on. Same exact behavior. Changed out stator and regulator to new units. Still same behavior, in both the charging and the tachometer" the battery voltage drops to 12.4-Volts from 12.75-Volts, and the tachometer pegs on. I ran all tests again except DVA and I am getting measurements in all tolerances.
One other things: I have tested voltage at both the battery and the terminals at the engine. So I do not believe the battery is at play here (i.e. it is not generating the voltage necessary to charge)
Q1: Can magnets go bad?
There is clearance between the stator and everything seems fine so don't think my glue job was bad.
Q2: what else can play into the charging system here?
I feel like I missing something. I have tested all parts according to the Mercury troubleshooting. I have not done the DVA, but what would that tell me? I have put brand new parts on, so lets say it doesn't pass the DVA.
Q3: if all the parts are new and good, and diagnostic tests are good, what could cause this problem?