Mercury 60-HP BIGFOOT Not Charging

Electrical and electronic topics for small boats
dbtfree15
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Mercury 60-HP BIGFOOT Not Charging

Postby dbtfree15 » 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?

Tom Hemphill
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Re: Mercury 60-HP BIGFOOT Not Charging

Postby Tom Hemphill » Mon Jun 27, 2022 7:48 pm

Q4: have you been using the same battery since the problem began?

jimh
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Re: Mercury 60-HP BIGFOOT Not Charging

Postby jimh » Tue Jun 28, 2022 7:32 am

Q5: when you replaced the magnets into the flywheel, did you test the magnets for their N-pole S-pole field orientation?

Q6: when you replaced the magnet into the flywheel, did you orient them so the N-pole and S-pole orientation alternated from one position to the next?

Let's go back to the original problem:

Q7: what was the value of the fuse that opened but not until the holder melted from the heat?

Generally a fuse should open long before enough heat is created to melt the fuse holder.

jimh
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Re: Mercury 60-HP BIGFOOT Not Charging

Postby jimh » Tue Jun 28, 2022 10:45 am

Since replacement of multiple components in the charging system did not cure the problem, the cause of the problem may be external to the engine, in the form of a load on the charging system that is demanding excessive current from the charging system.

To test for this, use a Hall-Effect Clamp-On DC Ammeter (such as the FLUKE 325) to measure the amount of current flowing out of the engine when the engine charging system is working properly and trying to provide current to all attached loads.

Cf.: https://www.testequipmentdepot.com/fluk ... er-325.htm

A possible test situation: disconnect everything from the battery except the engine. This will remove all other loads that might be possibly demanding high current and causing the repeated failure of the engine charging circuit.

Another possible cause: a shorted conductor on the engine wiring harness.

jimh
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Re: Mercury 60-HP BIGFOOT Not Charging

Postby jimh » Tue Jun 28, 2022 10:52 am

Q8: is there another battery charger that is connected to the boat battery?

Q9: is the other battery charger being operated at the same time as the engine is running?

dbtfree15
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Joined: Mon Jun 27, 2022 12:00 pm

Re: Mercury 60-HP BIGFOOT Not Charging

Postby dbtfree15 » Tue Jun 28, 2022 12:40 pm

Thanks for the helpful responses.

Answer to Q4: Yes, I have used the same battery as it has been holding a charge (was 12.1 volts after sitting a year). But I guess I should try a new one.

A to Q5 and Q6: I did not test for N & S, I put them back on the way/direction that they were on before (they had stayed on the stator and I could see the vertical orientation. In terms of alternating poles, I did not specifically check, but they were attracting to each other, which I think indicates they were arranged N to S.

A to Q7: It was a 25-Ampere fuse, I replaced it with a 25-Ampere fuse.

A to Q8: There is a tender or trickle charger (12-Amperes) built into the boat. It is connected to the battery.

A to Q9: The battery charger was not plugged in, but was hooked to the battery.

Thanks for the instructions on the test. Looks like I should do the following:

1) Look at getting a legit flywheel, my glue job may have been uninformed.
2) Try a new battery
3) Disconnect everything but the engine and try again
4) Perform the test on what the load is

Will report back, appreciate any other feedback.

dbtfree15
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Re: Mercury 60-HP BIGFOOT Not Charging

Postby dbtfree15 » Fri Jul 01, 2022 7:01 pm

The Mercuty 60-HP BIGFOOT engine now has a new battery and a new flywheel.

I also tested the two regulators I bought; both had defects. They failed the diode tests in the manual (shorted from yellow to red leads).

I got two new regulators, one cheap one off of Amazon and then a proper one directly from CDI just in case.

I took everything but the ignition and engine off of the battery. Charged to 12.9 volts. Tested the cheap regulator and it matched the specification in the manual. Installed the regulator. Started it up. Immediately there was a drain on battery, and battery voltage decreases when engine speed increases.

The engine was shut off because I think there must be a short circuit. I prefer not to destroy more regulators.

I am not really sure where to start.

All other connections have been removed from the system.

The one thing I did find is if I put the black probe to the red regulator lead and my red probe to the ground/case I get continuity. When I put red probe to red regulator lead and black to ground, nothing. This indicates diode behavior to me

Is that expected? I haven't bought a FLUKE digital multimeter yet. Still need to check that.

dbtfree15
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Joined: Mon Jun 27, 2022 12:00 pm

Re: Mercury 60-HP BIGFOOT Not Charging

Postby dbtfree15 » Sat Jul 09, 2022 9:28 pm

FOLLOW UP

In order to make sure the stator and flywheel were working as expected and that the AC could be rectified, I bought a bridge rectifier and hooked it to the stator coil output. I measured the voltage output from the bridge rectifier at 19-Volt DC at engine idle speed, increasing to almost 45-Volts DC when the engine speed increased was increased by setting to full throttle. From this I inferred the stator (which is new) and the flywheel (which I had repaired) were working.

On my Mercury 60-HP BIGFOOT outboard engine the battery negative or ground connections tended to have a hard, black, paint-like coating. I thought this was some sort of protective coating, but,in the name of trying everything, I cleaned these all and reinstalled all the grounds in the engine. The battery side looked fine.

I also noted that the positive post on the starter solenoid to which the battery connects (and several other positive leads as well} was retained with a cheap-looking lock nut. The cheap nut also had crappy black paint on it, as did the washer and nut under the leads. I cleaned these up and replace the cheap-looking nut with a nicer nut.

I still don't know if that black coating was a protective film or some weird corrosion or someone painted something on.

After these tests and repairs, and with the installation of a new CDI-brand regulator assembly, the charging system is putting out 13.2-Volts DC at engine idle speed and close to 13.9-Volts DC when the engine speed is increased to full-throttle.

NEXT STEPS
I think the charging voltage output is acceptable. Now I will run the engine for about ten minutes on a hose adaptor in order to test the regulator. If the regulator does not fail, then I i will take the boat to a lake. I will report the outcome in a future post.

RETROSPECTIVE
Looking at the wiring diagram of the regulator, I guess the electrical problems and failures on my engine may have been caused by the regulator assembly not having a connection to ground. The moral of mt story: check the negative or ground circuit if there is a battery charging output problem.

jimh
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Re: Mercury 60-HP BIGFOOT Not Charging

Postby jimh » Sun Jul 10, 2022 11:10 am

I hope your ten-minute test leads to a longer on-the-water test, and that you have indeed made a successful repair of the failure of the battery charging output on your Mercury 60-HP BIGFOOT outboard engine.

dbtfree15 wrote:I still don't know if that black coating was a protective film or some weird corrosion or someone painted something on.
Particularly with engines sold under the Mercury brand, the use of a black coating on many electrical connections is common in my experience with those engines. I am certain the intended purpose of the black coating is to prevent any water from reaching the metal parts of the electrical connections.

There are several products called "Liquid Electrical Tape" sold under various brands that may be similar to the material used by Mercury.

In a low-voltage circuit like a 12-Volt circuit, a very small layer of insulating material can stop the flow of electrical current. An electrical connection that appears visually to be a good, solid, mechanical connection may indeed NOT be a good electrical connection due to just a very thin layer of insulating material--usually a corrosion of the metals--interrupting the circuit.

Another material that can be sprayed onto electrical connections to protect them against contact with water and subsequent corrosion of the copper or other metals in the connection is called Boeshield T-9. Boeshield T-9 is particularly useful with aluminum. For more information on Boeshield T-9 in marine applications, visit their website at

https://boeshield.com/marine/

The Boeshield website will give you some of the history of the product and its usefulness on marine engines.

Another product I have used is Evinrude DPL (for Dries, Protects, Lubricates). DPL is akin to WD40 in that is displaces moisture, and is an excellent insulator of electricity.

You can spray Boeshield T-9 or Evinrude DPL (or probably some similar product sold under the Mercury branding) on the engine power head as a protection against moisture and corrosion periodically. I usually do this after the last engine use of the season while the power head is still warm as a preparation for a long period of storage over the next eight months of non-use.

Because these product are transparent and more like a wax coating, I prefer them to the opaque black hard-drying material you described on the Mercury wiring.

dbtfree15
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Joined: Mon Jun 27, 2022 12:00 pm

Re: Mercury 60-HP BIGFOOT Not Charging

Postby dbtfree15 » Wed Jul 13, 2022 12:00 am

FINAL OUTCOME

The open water test is completed. {The battery voltage] was at 13.1-Volts at engine idle speed and increased to 13.8-Volts when the engine speed was increased to cruising speeds. I can't ask for much better.

Thanks a million for getting me going here.

[A new topic about the tachometer has been moved to its own thread--Moderator]