30HP Johnson isn't charging the battery

[atistang]

Model # J30ELES it is a 1990 model

I had the battery die on me while operating at the end of last season and I am now trying to figure out the problem

I checked for loose grounds and found one. Fixed that and it charges very slow, when I put my meter on the battery terminals the voltage creeps up about .01 volt every 10 seconds. If i turn on the nav lights it will slowly discharge. I checked the battery and it was 12.5 volts, after starting it was 12.4 (first start of the year took about 15 seconds of cranking) then it just slowly charged from there, I never seen anything over 12.5 after running it about 5 mins.

I tried to test the rectifier according to some procedures I found on here. One way I would get infinite, the other I would get continuity for a second then infinite. So IDK if that means the rectifier is bad or not.

HELP! IDK what to do at this point and I hate to just buy a new rectifier if that isn't the issue.

 

[gm280]

Have you tested the wires from the stator to the rectifier to see what they read? Disconnect the wires and set the meter to AC scale and read them. If there isn't voltage on them it is your stator bad and needs replaced. If there is voltage there, then the rectifier is bad needing replaced...

Of course that is banking on your battery working properly too. Charge it up and verify it charges and can handle a load. You could even take it to an auto parts store and have them load test it...

 

[boobie]

Best thing to start out with is have the battery load tested.

 

[GA_Boater]

When you see 12.5 volts, how fast is the motor running? Often you need run 2500-3000 RPM or more for max charging.

 

[F_R]

You need to do a valid test on the rectifier. ALL diodes need to pass current in one way only. Without looking it up, doesn't that rectifier have six diodes (3 yellow wires)? That would be 12 tests, one forward and one reverse for each diode. Many digital multimeters won't test diodes. Some have a dedicated diode test function. I like the old reliable way, an analog multimeter or a good ol' continuity light.

 

[atistang]

When you see 12.5 volts, how fast is the motor running? Often you need run 2500-3000 RPM or more for max charging.

I don't have a tach, but i put it in gear and gave it almost half throttle, id say it was over 3000 RPM

 

[atistang]

Have you tested the wires from the stator to the rectifier to see what they read? Disconnect the wires and set the meter to AC scale and read them. If there isn't voltage on them it is your stator bad and needs replaced. If there is voltage there, then the rectifier is bad needing replaced...

Of course that is banking on your battery working properly too. Charge it up and verify it charges and can handle a load. You could even take it to an auto parts store and have them load test it...

How much voltage should I have from the stator?

if the battery is bad, shouldn't I be able to unhook it after i start the engine and test the cables and see ~13 volts?

 

[atistang]

Best thing to start out with is have the battery load tested.

I might have to do that, I have always gotten an error when charging that battery, but it has also always served me well...

 

[F_R]

How much voltage should I have from the stator?

if the battery is bad, shouldn't I be able to unhook it after i start the engine and test the cables and see ~13 volts?

NO! That will blow the rectifier if it isn't already shot. Never disconnect the battery while it is running.

 

[atistang]

NO! That will blow the rectifier if it isn't already shot. Never disconnect the battery while it is running.

ok, good to know. I hope to get over there tomorrow and test the stator. so any voltage means its good?

 

[Fed]

Did you properly test the rectifier yet?
The stator is very robust compared to the rectifier.
Rectifier test is with an ohmmeter, a wild guess would be about 1.5 Ohms between the yellows while disconnected and no shorts to ground.
(Happy to be corrected on this)

 

[F_R]

Rectifier test:
1. Connect ohm meter or continuity light leads to one yellow rectifier lead and red rectifier lead. Should show either a high or low resistance.
2. Swap test leads. If was high resistance before, should be low resistance now. If low before, high now.
3. Connect test leads to same yellow lead and ground (rectifier case) Should be either high or low.
4. Swap test leads. if high before, low now If low before, high now.

Do the same four checks on all the other yellow leads.

Note there are four steps for each diode. Four diodes in a two-yellow lead rectifier, six diodes in a three-yellow lead rectifier.

If it passes all tests on all yellow leads, rectifier is good. If it fails any one test, rectifier is bad.

If using a digital multimeter, make sure it is capable of testing diodes. Some have a dedicatied diode test. Some use a sound to indicate continuity.

Forget about inventing your own tests. These are the valid ones.

 

[F_R]

Stator test:
1. Disconnect leads from rectifier and connect your ohm meter to any two yellow stator wires. Should show a low resistance. Don't get all hung up on exactly how much. Low is good. Connect test leads to another two yellows if it has more than two. Low is good.

2. Connect your ohm meter to any yellow stator wire and ground. Should shoe very high resistance, infinity, or ERR.

If it passes the above tests, the stator is good.

Forget about trying to do a voltage test on them. Nothing wrong with that if you insist, but these are the simple tests and are valid. Running AC voltage tests will only confuse you. Disconnected from rectifier, voltage will range all over the place according to RPM.

 

[atistang]

Rectifier test:
1. Connect ohm meter or continuity light leads to one yellow rectifier lead and red rectifier lead. Should show either a high or low resistance.
2. Swap test leads. If was high resistance before, should be low resistance now. If low before, high now.
3. Connect test leads to same yellow lead and ground (rectifier case) Should be either high or low.
4. Swap test leads. if high before, low now If low before, high now.

Do the same four checks on all the other yellow leads.

Note there are four steps for each diode. Four diodes in a two-yellow lead rectifier, six diodes in a three-yellow lead rectifier.

If it passes all tests on all yellow leads, rectifier is good. If it fails any one test, rectifier is bad.

If using a digital multimeter, make sure it is capable of testing diodes. Some have a dedicatied diode test. Some use a sound to indicate continuity.

Forget about inventing your own tests. These are the valid ones.

so test the resistance both ways, then switch to the diode test mode and check all the leads with that? I should get a beep one way then no beep the other correct?

 

[atistang]

Stator test:
1. Disconnect leads from rectifier and connect your ohm meter to any two yellow stator wires. Should show a low resistance. Don't get all hung up on exactly how much. Low is good. Connect test leads to another two yellows if it has more than two. Low is good.

2. Connect your ohm meter to any yellow stator wire and ground. Should shoe very high resistance, infinity, or ERR.

If it passes the above tests, the stator is good.

Forget about trying to do a voltage test on them. Nothing wrong with that if you insist, but these are the simple tests and are valid. Running AC voltage tests will only confuse you. Disconnected from rectifier, voltage will range all over the place according to RPM.

I did check to see if the stator was grounded out, it read infinity.

I'll do these other checks after work today and report back.

Thanks for every ones help so far

 

[F_R]

so test the resistance both ways, then switch to the diode test mode and check all the leads with that? I should get a beep one way then no beep the other correct?

If it has the beep function, that is enough. Yes, beep one way and not the other. The beep indicates current is flowing through the circuit, which should only happen in one direction through a diode. As I indicated, the resistance test results might be confusing, depends on your particular meter.

 

[Vic.S]

If it has the beep function, that is enough. Yes, beep one way and not the other. The beep indicates current is flowing through the circuit, which should only happen in one direction through a diode. As I indicated, the resistance test results might be confusing, depends on your particular meter.

But the continuity beep may not work with diodes. I only have one meter with a continuity beeper and that does not..
The only way to be sure with a digital meter is to use the diode test range, or if it does not have a diode test setting to try it with a known good rectifier or diode to see just how it does behave and select a suitable ohms range to use

 

[atistang]

Rectifier test:
1. Connect ohm meter or continuity light leads to one yellow rectifier lead and red rectifier lead. Should show either a high or low resistance.
2. Swap test leads. If was high resistance before, should be low resistance now. If low before, high now.
3. Connect test leads to same yellow lead and ground (rectifier case) Should be either high or low.
4. Swap test leads. if high before, low now If low before, high now.

Do the same four checks on all the other yellow leads.

Note there are four steps for each diode. Four diodes in a two-yellow lead rectifier, six diodes in a three-yellow lead rectifier.

If it passes all tests on all yellow leads, rectifier is good. If it fails any one test, rectifier is bad.

If using a digital multimeter, make sure it is capable of testing diodes. Some have a dedicatied diode test. Some use a sound to indicate continuity.

Forget about inventing your own tests. These are the valid ones.

on step 3 and 4 I had low resistance one way and nothing the other on all 3 leads. I am going to order a rectifier now.


thanks for the help

 

[Vic.S]

on step 3 and 4 I had low resistance one way and nothing the other on all 3 leads. I am going to order a rectifier now.


thanks for the help

If by " nothing" you mean infinite resistance as opposed to zero resistance then your rectifier checks out OK.

 

[atistang]

If by " nothing" you mean infinite resistance as opposed to zero resistance then your rectifier checks out OK.

I just discovered that.

So according to these test the stator test fine and the rectifier test fine. I have now also replaced the rectifier.

I still get a very weak charge. If i put the boat in gear and give it about half throttle (out of the water) the battery voltage will creep up to about 12.8 volts, once i kick on nav lights, or any other accessory, the battery voltage starts to fall.

I'm going to have the battery tested tomorrow, I hope thats it. IDK what else to check if it isnt the battery