Guys I'm Stumped on Charging. Need Help!!

[Kiska Motorworks]

I'm working on a mid 80s Evinrude 40 horsepower for a gentleman. he hooked a battery up backwards and since then, he says he's not getting any charge to the battery. He had previously replaced the rectifier (3-phase 3-yellow) with a used rectifier, and it is testing just fine. Full diode test and resistance across all the yellow wires and grounds, and everything is testing as it should. In addition, I have tested the stator, and it tests fine as well. very slight resistance across each phase and no evidence of any short to ground. Even tested ac voltage when running and it seemed to be right in line with RPM from about 15 up to 50volts as it should be. Everything is wired correctly, yellows to yellows, red of rectifier to red of motor, gray wire in with yellow and gray wire etc, but I am not getting anything but battery voltage at the rectifier or at the battery. Hooked up to the hose, up to a couple thousand RPMs, but nothing changes. Even tried a different brand new battery but no difference. On a small aluminum John boat.

Thank you so much. Trying to get this figured out for the guy before I head off for Coast Guard duty on Friday.

 

[F_R]

Are you testing forward and reverse on all 6 diodes in the rectifier (12 tests in all)?

EDIT: You said "all yellow wires and grounds" How about all yellow wires and red?

 

[Kiska Motorworks]

To my best knowledge, I am testing this correctly across all parts and finding them testing correctly. I am going to test again tomorrow.

One potentially interesting thing,.... With motor running, I isolated the rectifier from the battery positive wire to test the output voltage and my volts were all over the place in DC going from 5 to 40ish. Thoughts?

 

[F_R]

Don't know what to say about your direct question about voltage because I've never attempted such a test. Why? Because running on open circuit (isolated from battery) is a good way to destroy a rectifier.

 

[Crosbyman]

I doubt a three phase rectifier will do sqwat to regulate those high voltages they just switch ac to dc

Hard to tell what is going on but testing on an open junction by ohms laws is testing the highest resistive point of the circuit (air) hence you will see max volts

careful not to blow anything else with those 40 volts

one solution is a regulator on the rectifier output so…..if you can't find a good a cure to the problem , feeding the weird DC volts to the battery via a regulator may work fine for you

btw volts don't mean much without amps ...maybe your stator (?) is cooked…. did you do any tests on the up side of your 3 phase rectifier ??

 

[Vic.S]

To my best knowledge, I am testing this correctly across all parts and finding them testing correctly. I am going to test again tomorrow.

One potentially interesting thing,.... With motor running, I isolated the rectifier from the battery positive wire to test the output voltage and my volts were all over the place in DC going from 5 to 40ish. Thoughts?

It is very unlikely that the rectifier will be any good if the battery has been connected with the polarity reversed.. It will have been fried almost instantly
The stator coils may also have been damaged.

The diagram below shows the circuit of a 4 wire rectifier
You need to test each of the 6 diodes in turn , measuring the resistance in each direction .
That makes 12 measurements in total

However not all the resistance ranges of a digital multimeter can be used to do this and it is impossible to predict which range, or ranges, will work. Meters vary Therefore use the "diode test" range.

Using the diode test range you will get no reading when the leads are connected one way and a reading equal to the forward volts drop when the leads are connected the other way for a good diode

If the rectifier is good you will have 6 " no readings" and 6 readings of around 600 ( or 0.600 dependimg on your meter)

Anything else is a "fail"

 

[Kiska Motorworks]

I doubt a three phase rectifier will do sqwat to regulate those high voltages they just switch ac to dc

Hard to tell what is going on but testing on an open junction by ohms laws is testing the highest resistive point of the circuit (air) hence you will see max volts

careful not to blow anything else with those 40 volts

one solution is a regulator on the rectifier output so…..if you can't find a good a cure to the problem , feeding the weird DC volts to the battery via a regulator may work fine for you

btw volts don't mean much without amps ...maybe your stator (?) is cooked…. did you do any tests on the up side of your 3 phase rectifier ??

I've completed all the stator tests that I can find and all seems to be fine, but obviously something that appears to be fine, is not. What specifically do you mean when you are referring to the tests on the upside of the rectifier? Thank you for your help,

 

[Kiska Motorworks]

It is very unlikely that the rectifier will be any good if the battery has been connected with the polarity reversed.. It will have been fried almost instantly
The stator coils may also have been damaged.

The diagram below shows the circuit of a 4 wire rectifier
You need to test each of the 6 diodes in turn , measuring the resistance in each direction .
That makes 12 measurements in total

However not all the resistance ranges of a digital multimeter can be used to do this and it is impossible to predict which range, or ranges, will work. Meters vary Therefore use the "diode test" range.

Using the diode test range you will get no reading when the leads are connected one way and a reading equal to the forward volts drop when the leads are connected the other way for a good diode

If the rectifier is good you will have 6 " no readings" and 6 readings of around 600 ( or 0.600 dependimg on your meter)

Anything else is a "fail"

When the gentleman brought the boat to me, he had already replaced the rectifier after reversing the polarity. The new one appears to test ok allthough I do have a new one on the way regardless and plan to test it again today. One other thing he did tell me is that he just bought this boat, he's never had it on the water and that he had never tested the charging before so it may be an unrelated issue. I simply, am not getting anything to the battery above battery voltage.
With an amp clamp, is there a good way, or what should I theoretically look to see in amps coming to the battery? Thank you for your help.

 

[Kiska Motorworks]

Don't know what to say about your direct question about voltage because I've never attempted such a test. Why? Because running on open circuit (isolated from battery) is a good way to destroy a rectifier.

I had run out of ideas at that time, already have a new one on the way so really was just trying to gather as much info and knowledge about the system as possible. I understand not theoretically a smart test, just curious with minimal risk.

 

[Crosbyman]

by upside of the 3 phase rectifier I was referrring to stator winding tests (voltages windings grounded coils...etc..)

 

[Kiska Motorworks]

It is very unlikely that the rectifier will be any good if the battery has been connected with the polarity reversed.. It will have been fried almost instantly
The stator coils may also have been damaged.

The diagram below shows the circuit of a 4 wire rectifier
You need to test each of the 6 diodes in turn , measuring the resistance in each direction .
That makes 12 measurements in total

However not all the resistance ranges of a digital multimeter can be used to do this and it is impossible to predict which range, or ranges, will work. Meters vary Therefore use the "diode test" range.

Using the diode test range you will get no reading when the leads are connected one way and a reading equal to the forward volts drop when the leads are connected the other way for a good diode

If the rectifier is good you will have 6 " no readings" and 6 readings of around 600 ( or 0.600 dependimg on your meter)

Anything else is a "fail"

Just retested the rectifier in all 12 tests. No continuity across any of the diodes in reverse and in forward bias, all diodes test about half a volt. On the surface appears to test just fine.

 

[Kiska Motorworks]

by upside of the 3 phase rectifier I was referrring to stator winding tests (voltages windings grounded coils...etc..)

Got it. I believe I have done all of the traditional stator tests and I'm not finding any shorts to ground or readings that appear off across the phases.

 

[Crosbyman]

"Just retested the rectifier in all 12 tests. No continuity across any of the diodes in reverse and in forward bias, all diodes test about half a volt. On the surface appears to test just fine. "

?????????

bad meter or bad luck.... diodes must conduct in one direction if you really have no continuity either way they are all bad (open) or you are not using the meter correctly or the meter is bad...

does themeter read 0 ohms when you short the 2 probes together ??

diode do not test VOLTS... they test :

open (high resistance) one way or closed (low resistance as in continuity..) the other way.


or I am nor reading your comment correctly..????​

 

[Kiska Motorworks]

"Just retested the rectifier in all 12 tests. No continuity across any of the diodes in reverse and in forward bias, all diodes test about half a volt. On the surface appears to test just fine. "

?????????

bad meter or bad luck.... diodes must conduct in one direction if you really have no continuity either way they are all bad (open) or you are not using the meter correctly or the meter is bad...

does themeter read 0 ohms when you short the 2 probes together ??

diode do not test VOLTS... they test :

open (high resistance) one way or closed (low resistance as in continuity..) the other way.


or I am nor reading your comment correctly..????​

Apologize my wording may have been confusing. What I was saying is no continuity in reverse, but I do have it forward as I should. I was using a diode test which is why my readings are in volts, i.e. the voltage drop across each diode and my reading of about half a volt each is what they should be reading.

 

[Vic.S]

"Just retested the rectifier in all 12 tests. No continuity across any of the diodes in reverse and in forward bias, all diodes test about half a volt. On the surface appears to test just fine. "

?????????

bad meter or bad luck.... diodes must conduct in one direction if you really have no continuity either way they are all bad (open) or you are not using the meter correctly or the meter is bad...

does themeter read 0 ohms when you short the 2 probes together ??

diode do not test VOLTS... they test :

open (high resistance) one way or closed (low resistance as in continuity..) the other way.


or I am nor reading your comment correctly..????​

If you are using the diode test range..... which is what you should be using, unless you have an old fashioned analog meter, ... the reading you get in the forward direction is the forward volts drop (in volts or mV depending on the meter)

 

[Vic.S]

Apologize my wording may have been confusing. What I was saying is no continuity in reverse, but I do have it forward as I should. I was using a diode test which is why my readings are in volts, i.e. the voltage drop across each diode and my reading of about half a volt each is what they should be reading.

Your tests on the rectifier seem to indicate that is is fine. I assume all these have been done with it completely disconnected .

Perhaps the stator coils are bad.. You should see a low resistance ( dont know the figures off hand) between any pair yellows but the resistance between yellow and yellow/ blue will be twice the value of the other two, but it is difficult to measure low resistances accurately without specialized equipment

Try checking the AC volts coming from the stator.. I dont know exactly what you will find ( It should really be done with a peak reading meter or with a DVA attachment on an ordinary meter on Dc volts)

For the full details of testing the stator coils see the CDI Troubleshooting Guide

 

[achris]

...

diode do not test VOLTS... ...

I'm sorry, but a modern digital multimeter, on the 'Diode test' function, displays exactly that, VOLTS. The voltage required for the diode to conduct when forward biased.

If you switch the meter leads and have the red lead on the cathode and the black lead on the anode, a good diode will read high (usually off the scale high) as the diode does not conduct when reverse biased.

Chris........
(Electronics and computer hardware tech since 1980)...

 

[F_R]

OK guys, it seems we finally got a valid rectifier test and all diodes passed. And the stator coil passed earlier. So, what the hey is wrong? Sorry to say I don't know either. The only thing I can think of is maybe the red rectifier lead isn't actually connected to the battery, ie could it be broken or burnt internally somewhere between the rectifier and the battery?

OR is the problem not with the charging system at all? How about an electrical load somewhere else in the boat taking more amps than the charging system can produce? Time for an actual Amps test of the charging system. By design, it can only produce a maximum of 5 Amps. Insert a suitable low-reading ammeter in series with the red lead.

This is starting to get interesting now.

 

[Crosbyman]

acrhis… ho well… been familiar with diodes myself (50+ y) and never had issues with them being tested with an ohmeter
( telephone tech , central office supv. & plant school instructor 30 y ) but i'll try that modern diode test

 

[Kiska Motorworks]

Your tests on the rectifier seem to indicate that is is fine. I assume all these have been done with it completely disconnected .

Perhaps the stator coils are bad.. You should see a low resistance ( dont know the figures off hand) between any pair yellows but the resistance between yellow and yellow/ blue will be twice the value of the other two, but it is difficult to measure low resistances accurately without specialized equipment

Try checking the AC volts coming from the stator.. I dont know exactly what you will find ( It should really be done with a peak reading meter or with a DVA attachment on an ordinary meter on Dc volts)

For the full details of testing the stator coils see the CDI Troubleshooting Guide

When I originally tested the stator AC voltage, I was using my power probe which does have a max reading and all though I don't recall exactly what the reading were, they seemed correct in relation to RPM's; somewhere between 20 and up to about 40 volts or so I believe.