75hp Mariner not charging battery anymore

[CDI Tech Support]

Re: 75hp Mariner not charging battery anymore

When you put the meter on the yellow don't forget to switch to A/C.

Standard AC measurements only measure RMS. DVA must be used because it's accurate whereas RMS is not. A digital meter does have built-in DVA. A DVA Adapter must be plugged into a digital meter in order to read DVA (peak AC voltage).

 

[ajgraz]

Re: 75hp Mariner not charging battery anymore

You mean Blue to Ground. The Blue (low-speed coil) is completely independent from the Red (high-speed coil)

Just going by what the book says. Maybe the 5200-6400 ohm low-speed spec already accounts for the 125-175 ohm in the high speed, I dunno.

Do not ever replace a component because it's only slightly out of resistance spec. Resistance is highly unreliable unless it's shorted or open. DVA is the only reliable measurement concerning an outboard.

Yeah, I guess if the spec was 5200-6400 ohm and you measured 5000 ohm you'd probably conclude it was OK. Maybe I should have said "failed badly."

Furthermore, quackerkiller has not mentioned experiencing a running issue, thus no checks to the low-speed or high-speed coils are necessary.

If it's not the rectifier, it's gotta be something, and that something is likely the stator. So why not do a complete check-up on the stator?

The proper DVA checks for a charging issue would be to measure DVA from the stator's Yellow to Yellow at idle. Should be 17-25V DVA connected to the rectifier & 17-50V DVA disconnected from the rectifier. This is mentioned in our "Battery Charging Issues" guide.

Agreed, you gotta get your hands on a DVA adapter for your meter.

 

[CDI Tech Support]

Re: 75hp Mariner not charging battery anymore

If the diode tests checked out and the rect passed the tests as mentioned above, can I rule that piece out?

No. The reason why is because a diode check will not catch a leaky diode, which becomes leaky only when voltage is applied.

If I am to just put in a new stator and if that does't fix it, put in a new rect, do I run the risk of ruining the new stator if the rect is bad?

No. Only a shorted rectifier/regulator, connected with the engine running, for a prolonged amount of time will short out a stator's battery charge windings. Simply doing a quick crank to see if the battery is charging to ~ 14VDC will not harm a stator that is exposed to a shorted rectifier. If your rectifier isn't shorted, no concerns to a new stator.

 

[CDI Tech Support]

Re: 75hp Mariner not charging battery anymore

Just going by what the book says.

If the book (I assume you're referring to a service manual) says measure Blue to Red, the book is incorrect. The low-speed coil is completely independent from the high-speed coil.

Always check our Troubleshooting Guide. We've done a ton more research on OEM components than the OEMs themselves because our company was founded on repairing OEM components.

Maybe the 5200-6400 ohm low-speed spec already accounts for the 125-175 ohm in the high speed, I dunno.

Negative. Again, they're completely independent from one another. So they must be measured separately.

Yeah, I guess if the spec was 5200-6400 ohm and you measured 5000 ohm you'd probably conclude it was OK. Maybe I should have said "failed badly."

If it measured 1000 ohms, I would tell the customer/mechanic to measure DVA. Temperature, among many other sensitive factors, greatly affects resistance. It's simply a worthless measurement unless it's open or shorted.

If it's not the rectifier, it's gotta be something, and that something is likely the stator. So why not do a complete check-up on the stator?

Of course that's up to the individual.

But to diagnose a charging/tach issue, measuring the charge coils is futile.

Agreed, you gotta get your hands on a DVA adapter for your meter.

We preach it every day!

 

[quackerkiller]

Re: 75hp Mariner not charging battery anymore

The two yellow wires are comming from your stator and are a/c input. The red wire is the output (charges your battery) the gray is your tach.

Use a simple 12v probe style tester that you can get at any autoparts store. They usually have a neon light in the handle.

Disconnect the battery. Do not disconnect any of the wires to the rectifier/regulator.

Connect the black wire to a suitable ground point on the engine block and put the probe tip on the red wire. Start the engine and the light should glow bright.

Remove the probe tip from the red wire and put it on either of the yellow wires. The bulb should be dim but if you accellerate the engine it shoud brighten. Test both yellows.

If the light comes on at the red the rectifer is ok and the stator is o.k. replace the battery or replace or clean the battery cables and connections.

If the light does not come on at the red but does at both yellows then replace the rectifer/regulator.

If the light does not come on and brighten with increased RPM at one or both yellows replace the stator.

I doubt its the battery or cable because the tach quit.

Ok, I pulled the red wire off the rect, started the motor and tested for voltage between all three nodes and ground. Red to ground=0%. Front yellow to ground=20% (again just using a battery tester). Rear yellow to ground=0%

This means bad stator, correct? After all the discussions, i hope this was the answer because it was much easier than testing 18 different wires for resitance, dva, etc. Should I start pulling the stator, or at least hunting for corrosion issues? Thanks much guys!

 

[quackerkiller]

Re: 75hp Mariner not charging battery anymore

Now...how do I get the flywheel off?

 

[saumon]

Re: 75hp Mariner not charging battery anymore

http://www.mbsmfg.com/mercury-mariner-honda-flywheel-puller-lifting-ring.html
(remove the nut before!)

 

[CDI Tech Support]

Re: 75hp Mariner not charging battery anymore

Ok, I pulled the red wire off the rect, started the motor and tested for voltage between all three nodes and ground. Red to ground=0%. Front yellow to ground=20% (again just using a battery tester). Rear yellow to ground=0%

This means bad stator, correct?

A battery tester isn't a sufficient test. If obtaining DVA equipment is impractical, we suggest taking it to a qualified marine mechanic to measure the stator's DVA.

If you choose to shotgun troubleshoot (gamble), replacing the rectifier would obviously be the cheaper part to replace. But again, we suggest updating a rectifier with a combination regulator/rectifier to alleviate the battery's inability to properly self-regulate.

 

[quackerkiller]

Re: 75hp Mariner not charging battery anymore

I have the stator out now. I probably should have caved and got the DVA adapter but didn't. Is it too late to test the stator? I am gueesing that you need to have the motor running to test it, right?

 

[CDI Tech Support]

Re: 75hp Mariner not charging battery anymore

I have the stator out now. I probably should have caved and got the DVA adapter but didn't. Is it too late to test the stator? I am gueesing that you need to have the motor running to test it, right?

Yes, you must have the stator installed & to be able to crank the engine in order to measure DVA.

 

[quackerkiller]

Re: 75hp Mariner not charging battery anymore

What SHOULD the voltage across the terminals be at idle or any other given rpms?

 

[sschefer]

Re: 75hp Mariner not charging battery anymore

18-22vac on the yellows.