94' 112hp Evinrude Not Charging?

[JD466US]

My sons 18' skiff with a 1994 Evinrude 112 is not charging the battery like it should. I am getting a reading of 12.8v on my meter with the engine running at a high idle. I would like to know if anybody can give me some tips on how to ohm out the stator to see if it has gone bad. His tach is working and I have heard, but maybe this is wrong, that if that tach works that the rectifier would be good. Any help will be greatly appreciated.

 

[F_R]

That usually means the rectifier is ok, but not always. Don't assume, test the rectifier. That is far more likely than the stator. So, help us out here, is it an unregulated rectifier with two or three yellow wires and a red one? There are 8 tests you need to make on a two-yellow one, and 12 tests you need to make on a 3-yellow one. It has to pass all of them.

 

[JD466US]

It is the 3 wire rectifier with the 2 yellow and red wire.

 

[F_R]

OK, there are four diodes in that rectifier. Each diode required two continuity tests. Personally, I get less confused when using an analog multimeter, or even a simple continuity light tester. If you have a digital multimeter, be sure you know how to test diodes with it. Many are tricky or simply don't work.

Here is the routine: Make a continuity test between one yellow lead and the red lead. Should be either high or low resistance (actual numbers are not that important). That is test #1. Now, swap your test leads connecting to the same yellow/red pair. If it was high resistance before, should be low resistance now, if low before, high now. That is test #2. Repeat both tests between other yellow lead and red lead. That is test #3 & 4.
Now repeat both tests between one yellow lead and case ground. That is test #5 & 6. Finally, repeat both tests between other yellow lead and case ground. That is test #7 & 8.

BTW, if using a continuity light, the high/low resistances will show as light/don't light.

Do exactly as I outlined and don't be inventing other combinations.

 

[JD466US]

Okay I have run the tests as you outlined and am getting readings on half of the testing and then when swapping my leads getting no readings which I think should be correct. Now the values I am getting are fairly consistent, 218 k ohms to 268 k ohms. So I am guessing now the rectifier is probably good. So now what is the process for testing the stator, or is there something else I should be checking first.

 

[racerone]

Test ohms on the stator coils.----------What does it read yellow to yellow ?---------What does it read one yellow to ground ?

 

[F_R]

Should be pretty low ohms yellow to yellow. I don't know the specs without looking it up, but I'd guess less than 100 ohms, maybe even just a few. Either yellow to ground should be very high ohms, close to infinity, or best case scenario, infinity.

Maybe there is nothing wrong with your charging system. Maybe you just need to run it longer and at higher speed to build up the battery voltage as it charges. And maybe (?) you have something turned on that is using the amps as fast as the alternator produces them.

That thing only puts out about 6 apms max, so it takes awhile to to build up a full charge. Most people complain of overcharging on a long run.

 

[JD466US]

No there is something wrong, he replaced both batteries. When they go out and run it for a while then stop and shut the boat down it will not re-start so they either have to switch over to the back up battery or use the booster jumper to get it to turn over.

 

[Vic.S]

Just a couple of comments to add to whats been said above

Test the rectifier with a digital meter with a diode test range. Each diode will show no conductivity in one direction and a reading in the other direction equal to the forward volts drop of about 0.6 volts (or 600mV)

A meter without a diode test range may or may not work on one of the ohms ranges. An analog meter will work on an ohms range but will show infinite resistance one way and almost zero resistance the other way ( the same for a digital meter on an ohms range if it works at all)


If after starting you see 12.8 volts it suggests that some charging is taking place or the reading would be lower. although if all was well it should rise well above that . as the battery recharges.

With a charged battery at the outset you should get a good many re-starts before it needs recharging, If therefore you have a discharged battery after a short run it suggest a fault somewhere that is discharging the battery or you have too may bits of electrical gear switched on!

Testing the rectifier is a sensible thing to do but there seems to me to be another reason for the battery becoming discharged so quickly with no use.

There is a procedure for checking the rectifier while running the engine in the CDI trouble shooting guide http://www.cdielectronics.com/support/

BTW do not leave the batteries even partly discharged for longer than necessary or you will dramatically shorten their lives

 

[oldboat1]

Think I would want to be sure the starter and starter circuit is in top notch shape. Starter may be tired -- due for cleaning and brush replacement.

 

[JD466US]

Vic, I used a calibrated Fluke meter and when testing in the diode test range the forward drop readings are in the .4 range.

 

[racerone]

What do you get in ohms from yellow to yellow ? ---What do you get from one stator yellow to ground ?

 

[F_R]

If you REALLY want to see if it is working, insert a low-reading DC ammeter in the red wire. That will tell you how much juice it is putting out--no guesswork. Remember it is only designed for about 6 amps. If it is putting out 6 amps, and your battery does not charge up, either there is something wrong with the battery or you are using more amps than it is generating. It's as simple as that. Does your Fluke have a DC current function with at least 6A capacity (10A is better) ?

 

[JD466US]

Okay I disconnected the stator wires and with the Fluke set to ohms the readings are, the yellow to yellow was 21.5 ohms and the Brown to the Browns/yellow measured 593 ohms. Does this sound about right?

 

[Fed]

Yellow to Yellow should be closer to 1 Ohm.

What reading do you get on the fluke when you short its leads together?

 

[F_R]

Brown wires have nothing to do with battery charging. The 21 ohms does sound suspicious. But as I indicated I don't know the specs.

 

[Vic.S]

Vic, I used a calibrated Fluke meter and when testing in the diode test range the forward drop readings are in the .4 range.

fair enough . If you get that reading in the forward direction for all four diodes and no reading ( infinite resistance) in the reverse direction for all four the rectifier checks out as OK

Final check measure forward and reverse between the red and ground. Should then get double the previous reading forwards.

 

[Vic.S]

Yellow to Yellow should be closer to 1 Ohm.

What reading do you get on the fluke when you short its leads together?

Brown wires have nothing to do with battery charging. The 21 ohms does sound suspicious. But as I indicated I don't know the specs.

very definitely should not be 21 ohms
I have found a figure of 1.2 to 1.7 ohms quoted for the 6amp stator coil ( it's lower for higher current stators)

Just to clarify this is the resistance between the two yellow wires coming from the stator assembly, measure with them disconnected from the rectifier

 

[JD466US]

Correct, I removed the yellow stator wires from the connection block and measured between them and came up with the 21 ohm reading. If it needs to be 1.2-1.7 then there may possibly be a stator issue?

 

[F_R]

Or one of the yellow wires (internal corrosion?)