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**boscoe99** · 08-16-2013, 07:16 PM

It will be a whole lot easier for you to swap the rectifier/regulators from one motor to the other. Let us know what you see as DC voltage output from both the battery cables and the isolator leads. That is what I would do anyway.

Any peak voltage reading device should work.

I don't have a manual for your motor but for a 150 HPDI you measure the peak voltage from the lighting coil at cranking speed, 1500 RPM and 3500 RPM. Disconnect the connector and measure the two output wires from the lighting coil. 5.5 volts at idle, 37 volts at 1500 and 86 volts at 3500 RPM are the specified values.

If the lighting coil meets specifications then check the output of the rectifier/regulator using the dc volts function. Specs call for a minimum of 12.7 volts. If you see this value the R/R is OK. If below this spec the R/R is defective.

I presume that you have a Yamaha manual for your specific motor.

**ttles714** · 08-16-2013, 08:43 PM

thanks

Thanks for answering and the help.....yes, I have the manual .... When checking the different battery voltages I found that the port engine is putting out 14VDC to the starting battery but no voltage to the house batteries. It seems as though the starboard engine is struggling to maintain voltage on its starting battery as well as the 2 house batteries. Unless my thinking is off, I am thinking that the regulator is the problem, on the port engine, in that there is no voltage coming from the auxiliary cable.....Does that sound right to you ?? thanks again

**boscoe99** · 08-16-2013, 09:48 PM

Some isolator leads have a fuse installed at the engine end. Are you checking at the battery end of the isolator or at the isolator connector coming from the rectifier/regulator?

It is possible that the isolator side of the R/R output has failed. Swap R/R's from one motor to the other and retest.

Condition of the battery(s), cables, connections, etc. will all have an effect on the voltage seen at the battery. Maybe unplug and re-plug the connectors several times to help scrub off any corrosion build up that might exist within a connector. Remove, clean and reinstall the battery cables at both ends.

Keep in mind that the electrical output of this motor is nominally 35 amps. In best case. Motor needs some juice to run itself. Not much left over to charge a battery. If the battery is low it will reduce the voltage that is seen at the battery. When the battery is fully charged, and the motor is running at mid-power, I would expect that you would see 14 - 14.5 volts output.

**rodbolt17** · 08-17-2013, 08:02 AM

is the lead wire actually hooked up for the port side?
the OX66 motors consume about 9 amps to simply run.
this leaves you with about 26 amps to charge batteries.
divide that in half and you get about 13 amps per battery.
remember this charging is all above 1500 RPM.
at idle or *****ing speeds you get MUCH less.

its a stupidly simple system.
3 phase lighting coil supplies an AC voltage/current to the regulator/rectifier.

once rectified to DC current and regulated to below 15volts its sent to the battery.
you simply have 3 green wires to test for inputs and a two red wires to test for outputs.
under the fuse cover you will find the 80 amp fuses for isolator and engine battery charging.

**ttles714** · 08-17-2013, 08:54 AM

rodbolt and boscoe

Thank you both... much appreciated and more understandable than the Yam service manual.. . Question >> I was going to test the following >>With the engine running at about 2000 RPM test the green wires coming out of the lighting coil for ACV .. What voltage should I be looking for and the same between each of the 3 phases ???? On the red wires going into and out of the 80 amp fuses I would expect to see something between 12.8 and 14 VDC (depending on battery state) ,,,, Is that correct ???? Also , the manual has me a little confused ....It states " Before measuring the rect/regulator output peak voltage, disconnect the lighting coil coupler and remove the fuses. .... Ok so removing the fuses , I can understand, as it would remove battery load....But disconnecting the lighting coupler, I don't get. Doesn't that "feed" the regulator ??

Thank you both so much

**boscoe99** · 08-17-2013, 10:13 AM

The lighting coil is tested without being connected to the rectifier/regulator. It creates voltage whether it is connected or not. Actually, it being connected can affect its output voltage. Just like a battery will provide different voltages depending upon whether or not it is connected to a load or not. A battery is normally tested not connected to anything.

The rectifier/regulator on the other hand is tested while it is connected to the lighting coil, since it depends upon the lighting coil to do its job.

There are two kinds of tests. Loaded and unloaded. Loaded refers to all devices being connected when the test is performed. Unloaded means the device being tested is not connected.

I don't have a copy of the SM you have. It does not make sense to me the r/r being disconnected from the lighting coil. Also, a peak reading volt meter is not used to test r/r output since that output is DC not AC. What does Mr. Bolt have to say?

See examples below from a later SM that I believe has greater clarity.

**rodbolt17** · 08-17-2013, 10:34 AM

a peak reading meter can be used to test both ac lighting coil and DC outputs.
remember though its reading a peak voltage not an RMS or working voltage so the numbers displayed will be slightly higher than normal.

**ttles714** · 08-17-2013, 12:54 PM

Found it.. thanks Rodbolt and Boscoe

Thanks to both of you especially since the Yam manual has an error...!!!! Disconnecting the lighting coil to check the regulator made no sense. !!! Your suggestion about wiring and connections is what got me through this.. I found good DCV at the regulator output , but not at the Battery.... Working my way back with a test meter I found the auxiliary charge line to be rotted/ corroded and almost separated within the 2" corrugated rigging tube. Probably got nicked or cut when the boat was rigged in 2001 !!. I had plenty of excess rigging wire so I cut it out and re connected with a solder joint and heat shrink tubing. Thanks to both of you for your help and effort.

Tony

**IFish4Tuna** · 07-08-2021, 12:38 AM

Here is the page from the Service Manual - this is from my 1999 0x66 250HP. I have also found it very confusing reading the manual. I may be back here for questions...Charging.jpg

**boscoe99** · 07-08-2021, 07:30 AM

Yamaha manuals are written for trained mechanics. That which is obvious to them may seem confusing to the untrained.

I presently have an interest in physics. I read and read and read. It is confusing. Every now and then a light goes on. Something becomes less confusing.

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checking lighting coil / regulator

checking lighting coil / regulator

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