Stator failures

what is the root cause of most

what is the root cause of most stator failures?i have heard of and experienced more stator failures(open coil) in the past 10 years than i have in the prior 40 years of boating?is there anything an owner can do to reduce the risk of stator failure?thanks

"When You say stator failures,

"When You say stator failures, most stators at least on the bigger engines with electric starts have a double mission.
1: Charge the power pack capacitor.
2: Charge battery through regulator/rectifier.

The part that most often fails and may even be the reason for the first one to fail, is the second one, battery charge coils.

Most 'common' reason is overheating of the stator caused by to high output.

This again might be caused by quite a number of items:
1; Recharging an empty battery. The systems are not designed for recharging of 'flat' batteries, but maintanance charging.
2: High output - low rpm. When trolling and running well pumps. lights +++++ You often takes what is possible to take, and the rest from the battery. At lov rpm, the flywheel gives the lowest cooling and air circulation.

3: Too big battery bank relative to charge capacity of the engine. It is similar to '1' in result.

4: Bad ground connections!!!!

5: Modern design! High output coils, small in size. The thinner the thread used in the coils, the more output, but the bigger risk of dammage/breakes due to overheat (core expansion may just rip off the thread)!!!

How to avoid?

Ballance the battery bank to the charge system.
Use seperate consumption and start batteries instead of one big battery.
Keep the batteries fully charged. Amazing what a small solarpanel may manage. I use a 30 Amp panel to keep 3 x 70Ah batteries fully charged when I 'm not using the boat!
Keep battery and ground connections clean!"

quick responce...ty very much.

quick responce...ty very much....i am interested in where to purchase the solar panel setup...i thought i had solved the battery charging system with so called trickle chargers but after boiling 2 batteries i realised that is not the answer..

"Mine is a simple set up, a pa

"Mine is a simple set up, a panel some 40 x 60 cm on an aluminum plate, cable on which I just added a plug so I can disconnect and put away.One std solar panel regulator put as close as possible to the batteries (25 cm). Note that I have been using std lead/acid batteries. Solars and gel is not a good combination on small systems.

http://www.mrsolar.com/page/MSOS/CTGY/wattsort

I do not know their location, but above a suggestion."

thanks very much.....got site

thanks very much.....got site on desktop to explore...

"In addition to the above.....

"In addition to the above.......

The 35 ampere charging stators that made their first appearance on the scene about 1984 have a tendency to run quite hot. Although the flywheel is ported with cooling holes, the heat generated does in time cause the large black coils that supply AC voltage to the powerpack(s) to melt down.

The time period between meltdowns of course varies with the degree of use, hours of use of the engine. Unfortunately there is no cure to this problem and it will reoccur at some point in the future.

The usual cause of stator failure on smaller ampere charging units is usually that a battery or battery charger is hooked up backwards resulting in reverse polarity. The rectifier in the charging system will not tolerate reverse polarity and blows/fails immediately.

This elimination of the rectifier results in having the AC voltage that normally converts thru the rectifier to DC voltage to charge the battery to back up within the stator. This results in excessive heat, causing the stator to crack and/or melt down similar to the higher rated 35 ampere model.

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc"

just to add the mercury 175 sp

just to add the mercury 175 sportjet which is 2000 and newer have a tendency to drop the low speed pickup to one switchbox quite frequently im not shure why this is . the problem creating this is the two yellow wires two red wires are zip tied together at there connections they get hot and melt together causing b+ to join ac. you must replace stator and regulator if you want problem to go away.my question why is it taking out the ign. driver and not the charge coils

"this is a good topic, another

"this is a good topic, another question i toally agree with heat being a problem. but why do the forien stators rarely fail they are rarely apoxied . are they designed better? how do the cool better?"

"This may be of interest to u

"This may be of interest to u guys---,..SIERRA MARINE,and CDI/RAPAIR,..are not enclosing thier stator windings in the plastic coating/potting,which both claim excess heat is diverted away much easier,which makes sense."

"JWB..... I've heard about

"JWB..... I've heard about that also, BUT back when this type ignition (Magneto Capacitance Discharge) first came into being (1973), the stators were also what would be called "Bare" (No Potting Enclosure). This resulted in many of the 3 and 4 cylinder stators having the black (ignition) coils encountering excessive heat and going into the meltdown process.

Their (OMC) cure was to add the potting enclosure which seemed to work as very few stator failures were encountered on the 3 and 4 cylinders thereafter.

BUT (Always Another But), the 35 amp stators have never been protected in any type enclosure to begin with..... and they do melt down. This makes me wonder about the claims of the companies you mention.

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc"

i notice from looking at some

i notice from looking at some pictures in parts section of sites that some stators have exposed windings....probably just dipped in varnish or something..this makes sence to me...either way we cut it its a design problem and should be known by now to the manufacturers....a stator is a ""dead in the water situation"" and should be a rare if ever failure..a reversed hookup or poor connection or overload as Joe and/or Morten mentioned is cause for failure and i can understand it but these things are failing for experienced boaters..heat dissapation is something that should be and can be addressed in design and/or problem follow up by the manufacturers..it would be interesting to know what the failure rate of mecury or evinrude is compared to the japanese manufacturers...wonder what a few holes drilled in a cowl would do to the heat?thanks for the input...

"In the around 15 years i was

"In the around 15 years i was running my marina and dealing with the OMC engines from late 80's into this century, the number of stator changes were minimal.
In the very few cases I had, there was only one I may remember that was 'unexplainable', and that was on a V4/60.
In all other cases it was possible to trace it back mostly to 'handling' errors, and in general as described in my previous post. I find it a bit 'unfair' blaiming stator designs for breakdowns cause by burned out rectifiers/regulators due to 'abuse', the reason being reversed polarity of battery cables, use of battery chargers and system overloads. In fact the owners manual even specify battery sizes to be used.
If I was to attack any of the electronic components in general it should be the power packs that to me seems to have too litle 'safety margin', not to forget the optical sensor in the OIS system.
We must not forget that what we get on this board are the problems. What I experienced at the marina was both the ones working and the ones not, and stator probles was nothing I would concidder a problem.
I could list quite a number of other items on the Evinrude/Johnson engines that I would preferr to be improved, stators from my experience would not even be on the list.
However to put it brutal I would think that some 90% of all breakdowns pulled in to my marina with 'breakdowns', and that goes for every brand, the resons were in general caused by bad/lack of service and not to forget handling/operating errors."

I dont know if i was following

I dont know if i was following the rules of the board by even starting this discussion...if i was not then i will cease doing this sort of thing...i think there are several of us enjoying the interchange tho...right now i am thinking along a different line than i have ever thought of when it comes to batteries..i have always walked into a battery shop and bought the best battery on the shelf...after this discussion and the many regulator/rectifier failures posted on this board i have drawn this conclusion..the battery should be to owners manual specs and no stronger..this way if the battery is charged to a reasonable level when the engine is used after a layup there is less current draw on the stator as well as the reg/rectifier which would greatly reduce the heat in both...am i correct in this statement?thanks again...

"I think it is a perfect topic

"I think it is a perfect topic for this board. Perhaps Andrew may not agree, his business will be better if engines keeps on breaking down!
There is a reason for the battery specs in the manuals. The systems are designed to fit those specs, not what battery shops wants to sell.
So far I haver mainly mentioned what makes the charging coils (battery) overheat.
What in fact is a bigger problem for the users are when the power pack charge coils quits, the engine stops! How may they be overloaded? Their main function is to keep the capacitor in the power pack charged. This capacitor operates similar to a start battery, quick discharging of a certain amount of amps at a certain voltage to the coils. Like a starting battery, it is not a question of completely draining this capacitor at every time, You just take the 'top' of it.
The use of spark plugs with different specs than stated ('R' and not 'Q'), plug wires with different specs, faulty grounding, 'leaking' stop circuits, double fireing powerpacks etc are all exsamples of what may encrease the discharge of the capacitor more than intended. This again will lead to the power coils have to 'work harder' to keep the capacitor fully charged. More amps, more heat ...... = isulation starts melting and good bye stator and chatge coils!
You may buy 'fancy' add ons that encrease the power output of the coils and thereby perhaps the sparks, but in general only for a limmited time! Most often sooner than later the weakest link will fail, be the stator from overheat or the powerpack from wild jumping sparks!
This is one of the reasons for my 'fight' against the NGK 'R' plugs in the Evinrude/Johnson engines as well as use of plug cables with different specs than the originals!"

"Thanks again for all the inpu

"Thanks again for all the input...the discussion has opened up a lot of thinking for me on checkpoints both on equipment and maintenance parts to use(batteries,plugs,etc}...actually i have been following the book so to speak except for the battery...lower unit oil,water pump,etc also..i personally have experienced only one stator ignition failure and it gave me notice that something was wrong with a hard start the day before after i had run about 25 miles and stopped to talk to someone..i have saw a few failures on other boats tho as i own a camp and am on the water a lot..i cant speak to maintenace habits of those people..thanks again and keep up the good work...Carl"

"I think this is an excellent

"I think this is an excellent thread... very useful.

I have been talking for quite a while about making an FAQ listing for each category of the board. Posts like this and others could be moved to that group so they would be easy for users to find.

I will try to do that soon and will ask for feedback on what to include.

Thanks as always! "

i think that is an excellent i

i think that is an excellent idea...for example:in the short time i have followed this board there have been many problems reported in the rectifier/regulator area...last fall Morten went into some detail explaining to me in a post exactly what is happening in that area as regards batteries..and the different charging systems....including some good theory...this data is still available in the archives via search but there are three problems there.1.only a few of us know its there..2.its easy to miss something like that using a search argument..3.its too time consuming to make it worthwhile unless you know it is there...therefore a person with a problem will open a new thread and get support from a person that starts from scratch and even the support person probably dont know the old thread exists..a faq would immediatedly make that data available to everyone...result for you = satisfied potential customer... i can also think of other things that could be answered there that very few people pay attention to..what are the recommended minimum tools that a owner should have in a boat? where can a person buy a truly waterproof box for these tools?where can a person purchase these tools?many things can be covered via FAQ section..thanks again..Carl