Altenator or Voltage Regulator?

[gammalight]

Hello All,

I have a 1986 Stingray bowrider that I purchased 6 months ago. Along the way I have been fixing problems here and there and noticed this problem recently. It does not seem that the battery is being charged while the engine is running. The battery is brand new, I also I have a brand new starter, starter solenoid and slave solenoid. I will charge the battery to about 12.5V and at the end of the day the battery reads 11.9V. If the battery voltage is 12.0 when I start the engine, the voltage at the battery is still 12.0V. From my understanding the voltage should be 1.0V - 2.0V higher while the engine is running,

So I tested the voltage at the voltage regulator. There are 2 wires coming from the stator, one wire going to the starter and another wire going to the circuit breaker and that wire from there goes to the starter as well.

The orange wire coming off the VR going to the starter always reads whatever the battery voltage is.

The red wire coming off the VR going to the circuit breaker always reads whatever the battery voltage is.

One of the red/yellow stripped wires coming off the stator reads a variable voltage depending on what the RPM's are. This voltage is reversed when I put the red lead on it from the DMM. I believe the voltage ranged from -6.0 - -30V from 1000 - 3000 RPM's

The other wire coming off the stator read a variable voltage and was reversed as well. The voltage was not reading as high throughout the same RPM range as the wire above.

Basically with the information above do you think it is the Voltage Regulator that is at fault or is it the Altenator/Stator?

Please let me know if there is anymore information I can provide.

 

[gammalight]

Re: Altenator or Voltage Regulator?

Okay I just rechecked the voltage coming from the stator, didn't realize it was an AC voltage. The voltage is variable about 20V at idle and 70V at 3000RPM's.

I am thinking the problem is the voltage regulator.

 

[Splat]

Re: Altenator or Voltage Regulator?

Do you have an alternator or a stator? They are not one in the same and will have one or the other.

I'm thinking you have a stator. This will entail two wires coming from a coil under the flywheel.

How many HP and what brand engine?

Are you seeing any increase in the battery voltage with the engine running at quarter to mid throttle?



Bill

 

[gammalight]

Re: Altenator or Voltage Regulator?

Hey Spat,

It is a 1986 3.7L Mercruiser 190hp engine

Yes, it is a stator and the Voltage from the stator increases from ~20V at 1000 RPM to ~70V at 3000 RPM. The voltage on the leads going to the circuit breaker and to the starter read whatever the voltage is on the battery. The voltage at the battery while the engine is running and the RPM's are increased never changes.

So what do you think the problem is? THe stator or the voltage reg?

Hope this helps

 

[flargin]

Re: Altenator or Voltage Regulator?

if your alternator is producing voltage over 15v, then it is either your rectifiers or your regulator. I would say it is likely your rectifier, as that will result in high voltage DC, and if you did not find that, it is likely the rectifier. The rectifier will then feed the regulator, which clips the voltage down to 15v

search for testing your diode, here is one.

 

[gammalight]

Re: Altenator or Voltage Regulator?

if your alternator is producing voltage over 15v, then it is either your rectifiers or your regulator.

Yeah, thanks for the help but above your post I clearly say I have a stator. I would think with my current set up that the rectifier is internal in the voltage regulator housing. The stator is working correctly. There is no voltage change coming off the regulator when the RPM's increase. The voltage reading coming off the regulator going to the starter and the circuit breaker is whatever the battery voltage is.

I have not found a way to test the regulator independently but theoretically can I not start the boat and disconnect the battery and if the boat shuts down then the regualtor is definitely the problem?

 

[bruceb58]

Re: Altenator or Voltage Regulator?

I have not found a way to test the regulator independently but theoretically can I not start the boat and disconnect the battery and if the boat shuts down then the regualtor is definitely the problem?

Don't do that, it will blow your regulator. I really think your best bet is to ditch the whole charging system you have and buy the alternator kit available for your engine.

 

[gammalight]

Re: Altenator or Voltage Regulator?

Thanks for the reply, I have been reading a lot about the alternator conversion tonight and I believe that is the route I am going to take. I am looking at the kits from breeze works.

A couple of questions first though.


Do I have to take the stator and magnets out? If so, how involed is it?

Can I just take the leads coming from the stator off the regulator and terminate them?

Can I leave the regulator on so I do not have to buy a new hose and just not have any hot wires going to or from it? I know its kind of lazy...

I have power steering on the boat, so from what I understand do I have to get the low mount kit with the long belt?


Any input, advice, tips or tricks would greatly help out!

Thanks!

 

[gammalight]

Re: Altenator or Voltage Regulator?

I just wanted to close this post out and give everyone an update. I ordered the 3 wire altenator kit from breezeworks and installed it on the boat. It took about 2 hours to install and set right. I had to move the cooling system resevoir and rearrange some hoses but the set installed beautifully and works perfectly. I also just disconnected the stator wires from the voltage regulator and from the regulator to the starter. I could not be happier with the system.

Again I have the much disliked 3.7L Mercruiser 190 engine but with the altenator kit and 4" heat exchanger it is a really good engine. I have never had any problems with mine. Moving closer to the end of the season, while winterizing the boat, I will go through a very detailed check and inspection of the engine and stern drive to make sure no other problems exist.

 

[Silvertip]

Re: Altenator or Voltage Regulator?

Or you can destroy a perfectly good rectifier/regulator by disconnecting the battery with the engine running so you prove nothing. Don't do that. IF you have the proper AC voltage from the stator and nothing out of the regulator, and the rectifier is integral with the regulator, you found the problem -- replace the rectifier/regulator.