Stator Vs Alternator

[4hand]

I have an OMC Sail Drive Zephyr engine in a 1982 C&C sailboat I restored about 10 years ago. It has both a Stator and an Alternator (I realize serve the same function in charging the batteries). The alternator was added by the previous owner. The stator is 9 amps and the alternator is 35 amps (according to the manual). I recently motored about an hour to a haul out lift (redoing the bottom) and the batteries died at the end of the trip. The belt from the fly wheel to the alternator was very lose, floppy lose. If this is the reason the batteries died the fix is simple however I don't know for sure. I can't crank the engine to test the alternator because the boat is not in the water and there is no hook up for a water supply on the engine lower unit. Here is my question; "Because there is an alternator does the charging and wiring process associated with the alternator over ride or neutralize the stator?" "Do they work together or are they independent of each other with a single wiring harness for one or the other but not both?" Any ideas will be very helpful. Thanks

 

[gm280]

First of all, welcome to iboats :welcome: Glad you could join us.

WOW, a lot to try to cover here. First of all, not knowing how the previous owner connected up the add on alternator, it is going to be very hard to make any quality determination as to whether the engine stator and the alternator are running together or separate. If you knew the wiring of each, then a better idea could be made. But seriously, not really knowing how the two are working, it isn't really possible to answer your question. The stator on the engine could only be recharging the battery while the additional alternator used for other things. Or even visa versa... If you can trace the wiring to give more info, that would help!

 

[4hand]

thanks for the welcome. I had hoped someone would tell me only the stator or alternator could be used not both at the same time. I'm not sure why I thought it would might be simple. I'll be at the boat in a day or so and try to figure out the wiring. Regardless of which is wired to what, any ideas as to how to determine if the charging system is working or could work without the motor running. Maybe an OHMS test of some type to determine positive potential current flow? It may be I have to wait until the boat is in the water to test everything. I'll let you know what I come up with on the wiring. Here's wishing you a happy new year.

 

[Barnacle_Bill]

A stator's primary purpose is to provide power for the ignition system. Stators that also charge the batteries have separate coils on them for that purpose.

 

[Silvertip]

In your original post you stated that the "batteries" died -- implying there are more than one. If memory serves me, a sail drive is in the 9.9 - 15 HP so the 9 amp output from the stator would be fine for one battery but not likely enough oomph to keep two batteries topped off. Thus the reason for the added alternator. So the stator may be charging just one of the batteries -- possibly the starting battery while the alternator charges the "house" battery. As was indicated however, without more detail on the actual wiring it is hard to say what's going on with that setup. If the batteries "died" as you put it, you are advised to remove them from the boat and charge them immediately or they will be toast if left in an uncharged state for any length of time. Keep in mind also that if these batteries are very old, they may have one or more bad cells which would prevent them from accepting a full charge. To prove the batteries are or are not ok, fully charge them and then take them to any local auto store for a "generally" free load test. The engine must be running to verify that either or both charging systems are or are not working.

 

[racerone]

No ------The zypher is the big 35 HP powerhead with tiny intake ports to limit the thing to about 15 HP or so.----Have a factory new block on the shelf for one.----Post pictures of the original rectifier and where does the red wire from the rectifier go ?

 

[4hand]

I appreciate the information and input. I haven't been to the boat to check out the various wiring issues that have been presented. I'll be replacing the depth meter tomorrow or the next day so I will check things out and get a couple of pictures. As I mentioned in my original posting I believe the problem is the belt needs replacing and tightening. However now that I have had the problem I need to know how my batteries are being charged. FYI, when I recharged them they would not hold a charge so I have replaced them with a small cranking/deep cycle battery and large deep cycle 34m as a house battery.

Racerone you are correct about the power head. The sail drive is rated at 15 hp.

Silvertip you are right I mentioned both batteries. the reason both died is I wanted to charge them while I was motoring to the boat yard so I had the selector switch on ALL. I didn't know the alternate or stator (?) was not charging and both died. they were new in 09. they weren't true deep cycle batteries to begin with. I'll have more information and pictures next time.

 

[jhebert]

I have an OMC Sail Drive Zephyr engine in a 1982 C&C sailboat I restored about 10 years ago. It has both a Stator and an Alternator...

The component you are calling "a Stator" is a permanent magnet alternator, sometimes called a magneto. The component you are calling "an Alternator" is a field-coil alternator. They are both alternators. They both generate pulsating DC current.

Typically in small outboard engines the battery charging current is created by the permanent magnet alternator. The coil windings for this alternator are usually part of a multi-coil assembly, called the stator. Other windings in the stator generate other currents used to operate the engine.

No details have been give on the wiring of these two alternators to the batteries. In general, I don't think it is a good plan to connect in parallel the outputs of two alternators, and this is based on my own experience. These small outboard engine alternators seem to be prone to damage if they are connected in parallel with other charging current sources. Many years ago I bought a twin engine outboard boat. The two engines' main power cables were wired in parallel and connected to a common battery. Their alternators were thus in parallel. One engine had a blown alternator. When I repaired it, the alternator on the other engine failed in a few minutes. My conclusion: don't connect them in parallel. I repaired the second alternator, and re-wired the boat to isolate the alternators. No further alternator failures occurred in the next 15 years.

If your boat is wired so the two alternators are wired in parallel, you may be experiencing the same sort of problem I described above.

 

[4hand]

racerone - you mentioned a new block on a shelf. do you our anyone else have contacts to locate engine parts for a Zephyr sail drive model # MO585803. I need to replace the impeller. I need an impeller plus the gastics. any contacts will be greatly appreciated. Thanks, 4hand