Charging problem-revisited

[fishnfun]

I posted last fall about a charging problem on an 86 Johnson J50TLCDE. Schematic was kind enough to send me some info that helped a lot. I thought that the problem was solved--but. The voltage at the battery, measured by the depth finder, will only crawl up to ~13V (sometimes) after several minutes of ~5000 RPM.<br /><br />The specs I got from Schematic call for 0.27 ohms +/- 0.05 ohms from the yellow/grey to the yellow/blue and the yellow. I read ~0.3 from the Y/G to Y/B, and about 0.5/0.6 to Yellow. (My digital multimeter will only display one decimal point.)<br /><br />The engine runs fine and the tach works fine. The rectifier seems to check out OK. There is nothing else in this charging system, right? Am I missing something or is it the stator?<br /><br />Yeah, I know, I'm waiting on a manual to get here, but the crappie are calling me. Hey Schematic, why don't you fix us up with a peak reading adapter for cheap?<br /><br />Thanks

 

[petryshyn]

Re: Charging problem-revisited

Yo fishnfun <br /><br />You won't get any cheaper than <br />this for a peak reading adapter. The peak reading adapter is only valuable for checking out your ignition, not the charging circuit.<br />Your ohm readings appear to be OK. The slow rise in voltage at the battery could be caused by a low battery, a bad battery, bad connections or accessory drain (lights, radio, finder,etc.). A low battery will take a long time to charge, therefore the voltage is held down until battery is charged up. Try charging your battery up before going out next time. The next test you could perform is to determine how much current the charging system is capable of producing. Thats the real world best test. You need a clamp-on DC ammeter.(not cheap) or shunt type built in to a multi-meter. Before we get into that, charge the battery before going out next time and see what the voltage does after a few minutes.<br /><br />Good luck!

 

[almost retired again]

Re: Charging problem-revisited

Hi Fishnfun<br />You don,t really have to have a peak reading meter, the meter that you are using is reading RMS values or otherwise effective values which is 70% of peak values. Just multiply your meter readings by 1.414 this will put you in the ball park.<br />good luck

 

[fishnfun]

Re: Charging problem-revisited

Thanks for the replies. Sorry to take so long to get back to this, but I wanted to have some info to work with.<br /><br />So...I charged the battery. It seems to only want to take ~3/4 charge (per hygrometer). Schematic, I looked at some of your earlier postings about how people abuse batteries, and I resemble that remark! However I don't think that is the problem here. I have taken the boat out twice and monitored the voltage. I get no increase of volts till ~4000 RPM, and then only a slow rise to around 13.5V. These readings were taken with no load, lights, radio, etc., only a VOM connected to the battery. Below that, I get no rise, only battery voltage ~12.5. <br /><br />From what I can gather, the charging system is rather anemic to start with, only putting out about 4-5 amps at best.<br /><br />I think that I am only getting one half of the sine wave. See the original post relating to the ohms. <br /><br />Schematic, I was aware of the adaptor that you linked to. I thought you might send us to Radio Shack for a $2.99 part. You know how it goes, if you have one at your disposal you don't ever need it <G>.<br /><br />Thanks for the help!

 

[fishnfun]

Re: Charging problem-revisited

Thanks for the replies. Sorry to take so long to get back to this, but I wanted to have some info to work with.<br /><br />So...I charged the battery. It seems to only want to take ~3/4 charge (per hygrometer). Schematic, I looked at some of your earlier postings about how people abuse batteries, and I resemble that remark! However I don't think that is the problem here. I have taken the boat out twice and monitored the voltage. I get no increase of volts till ~4000 RPM, and then only a slow rise to around 13.5V. These readings were taken with no load, lights, radio, etc., only a VOM connected to the battery. Below that, I get no rise, only battery voltage ~12.5. <br /><br />From what I can gather, the charging system is rather anemic to start with, only putting out about 4-5 amps at best.<br /><br />I think that I am only getting one half of the sine wave. See the original post relating to the ohms. <br /><br />Schematic, I was aware of the adaptor that you linked to. I thought you might send us to Radio Shack for a $2.99 part. You know how it goes, if you have one at your disposal you don't ever need it <G>.<br /><br />Thanks for the help!

 

[fishnfun]

Re: Charging problem-revisited

Sorry about the double post.

 

[petryshyn]

Re: Charging problem-revisited

fishnfun <br /><br />The next step is to be sure the rectifier is OK. You say it appears good, but how did you check it? Once we determine that it is good, we'll do a current output test. Then we'll do a voltage drop test. Then , once its fixed, and your still bored, we'll build a peak reading adapter for ignition testing in the future. Hows that?<br /><br />1st things 1st....<br /><br />>How did you check the rectifier?<br />>What kind of meter do you have?

 

[fishnfun]

Re: Charging problem-revisited

Dang Schematic, you are fast.<br /><br />I tested the rectifier with the diode function on my cheapo Sears/Craftsman digital VOM.<br /><br />Regarding the voltage drop test, I have disconnected the kill switch, and cranked the engine for several seconds. The voltage never drops below ~11.3. Is this where you are heading with this test?

 

[petryshyn]

Re: Charging problem-revisited

I don't mean to test you, but how many tests did you perform on the rectifier? There are 6 diodes involved here, and I don't want to presume anything.....

 

[fishnfun]

Re: Charging problem-revisited

Ok, from ground to each of the leads that connect to the stator leads--all check good in one direction and high ohms in the other direction. For some reason, I don't have the exact values written down.<br /><br />From the red lead (output) on the rectifier to each of the other leads, all show 520 to 525 ohms in one direction, and high resistance the other way.<br /><br />For what it is worth, all the tests were done with the battery disconnected and all the leads seperated at the terminal block to isolate the components.

 

[petryshyn]

Re: Charging problem-revisited

Ok, I'm happy with that. Reconnect everything and start engine. At 2000-3000 rpm, measure voltage from rectifier ground terminal to rectifier positive terminal and record. While maintaining the same speed, measure the voltage across the battery posts. The 2 voltage readings should be within .2-.5V Let us know, and we'll continue.....<br /><br />(just for the record, the readings you get with the diode test function is not resistance, its voltage drop)<br />

 

[sirlespat]

Re: Charging problem-revisited

from sirlespat,<br /><br />When calculating peak voltages from rms multiplying by 1.414 is valid only for a sinewave type waveform. If you are checking battery voltage there is a dc compnent (battery voltage) with a charging voltage added to the top so not really relevant. some kind of guide can be obtained by measuring dc and ac voltages under charge at various speeds the ac component will indicate to some degree output from the charging circuit. Can you tempoarily swap in a known good battery (eg wifes car!!)<br />regards

 

[fishnfun]

Re: Charging problem-revisited

Schematic, I have trouble getting a good reading at the rectifier terminals, due to what I suppose is RF interference? I can attach the hot lead there and move the ground lead to a location further from the coils, etc. and get a "good" reading. If both are attached at the rectifier leads, the reading bounces all over the place.<br /><br />I have ~0.1 voltage drop from that "good" reading to the battery terminals.<br /><br />Sirlespat, so you are not married I take it <G>. I tried it with a "known good" ie. new battery with the same results. The other (<1 yr.) battery passed the load test fine.

 

[petryshyn]

Re: Charging problem-revisited

Lets approach this differently.<br /><br />*run engine at 2000rpm<br /><br />>connect meter red lead to rectifier red lead<br />>connect meter black lead to battery positive post<br />>record reading<br /><br /><br />>connect meter black lead to rectifier case<br />>connect meter red lead to battery neg post<br />>record reading<br /><br />Add readings together....what did you get?<br />This will check for any voltages losses in the system. <br />If this checks OK, we'll test current.<br />If current is low, stator is at fault.<br /><br />

 

[fishnfun]

Re: Charging problem-revisited

Ok so I still get wildly varing readings. Changing so fast you can't read them. Something in the range of -18V to +3V. It does this regardless of which direction the leads are connected??

 

[petryshyn]

Re: Charging problem-revisited

do you get the wild readings on both the positive and negative lead checks?

 

[fishnfun]

Re: Charging problem-revisited

Yep, sure do.

 

[petryshyn]

Re: Charging problem-revisited

do you have an ammeter, or the amp function on your multimeter that will read 10 amp or better?

 

[fishnfun]

Re: Charging problem-revisited

OK, update time. Schematic, I have an old auto ammeter that is not senitive enough to do the job. So, I'll use the 10A function on the VOM, right? Well it shows 1 (out of range). So I try it with the battery charger set on 2A. Same thing, out of range. By now I am getting pretty hacked at this whole situation. So I get my hands on another VOM (minus the 10A function).<br /><br />Presto, now things are looking up. Now I can check for voltage drop as you suggested. ~.1V Went back through the entire test sequence: stator; Y/G-Y .5 ohm, Y/G-Y/B .3 ohm, Y/B-Y .3 ohm. No shorts to ground. Rectifier check using diode function: good with all values very close to the same (forward current, voltage drop whatever--noted Schematic, it is not ohms <G> ).<br /><br />Hook up battery only, NO acc. not even tach. Fire it up, no voltage rise, just as before. Voltage drop from rec. to bat. ~.1V. I realize it is not a correct reading, but for comparison, measured AC output at stator leads: Y/G-Y= 8.8, Y/G-Y/B =5, Y/B-Y =5.<br /><br />I tried this in the very beginning and got screwy (erratic)#s and should have known something was wrong--my bad on that part. I went back to the other meter, using the SAME leads (to eliminate that as a source) I had just used, readings all over the place again. Now, putting either lead in roughly the cowling area, just in space, don't have to be touching anything, numbers all over the place. Regardless of where the other lead is--seems to be getting progressively worse. Remember my RF interference comment? The meter is less than a month old so Sears is getting the piece of crap back.<br /><br />Which leads me right back where I started, to the stator. A dealer showed me one that he says is correct, but the part #OMC 582926 will not cross reference to any thing I can find. All the after market manuals list one for this engine but it sure don't look like what the dealer showed me?<br /><br />Sorry to be so long winded but the moral I guess is make sure you are not trouble shooting one piece of @$#% with another one. Hope this might help somebody.<br /><br />Any more sage advice before I pull the flywheel? Thanks.

 

[petryshyn]

Re: Charging problem-revisited

fishnfun <br /><br />1)First off, when measuring low resistances below 1 ohm, you must calculate the lead resistance of the meter and subtract it from the reading you get of the component.<br /> <br />>connect test leads together and record reading. Thats the resistance of the leads. (eg .1 ohm)<br />>that .1 ohm must be subtracted from the readings of the stator<br /><br />*I must admit, some of the stator readings sound a bit off, but I'm still suspicious.<br /><br />2) I don't like purchasing parts unless I'm sure of the failure. You've tested the rectifier, and it reads good. You tested for voltage loss from rect. to battery and its OK (I hope you checked this at high RPM). The last test is to get a good working ammeter that will read 0 - 10 amps accurately, and measure the output current. That system only puts out 4 - 5 amps at 5000rpm. Do you know how to perform an output current test?