stator ohms test readings

Hi guyies. After haveing ign problems on a 1970 60 hp I went ahead and changed every part in the ign circut.The aftermarket CDI stator I put on Seemed to be reading a lot different from the service manual specks.It states at low ohms I should be getting a reading of 0.75- + or - 2 ohms. This CDI stator is reading 2.0 double of what the specks call for. I should be getting a reading between 0.95 or 0.55. This is supposely a 9 amp stator from CDI part# being 173-0744.My main concern with this high ohms reading is it possible for it to cause my rectofier and coil to burn out prematuerally ?The reason I ask is because when I replaced it 8 months ago I have had to replace the brand new rectofier and coil .Thanks Tony

Have you tried the trouble shooting section on the CDI website to see if if there is any specks there to help?Oldman570

Hi guyies,Oldman I have not looked up on the CDI site to trouble shoot.I plan on calling them to see what they have to say.It may just be a bad part and they can swap it for a good one.Kimcrwb I have a few stators laying around I am running one now that came off a 1972 100 hp.It is the same stator 9 amp and doing a cross check on site the # matched the same for my 1970 60 hp I did the ohms test on it and it was good.As for changing fly wheel that may be the key,butt it allso sounds kind of risky It just dont seem that would be safe Ill do some homework and get some feedback.If anyone out there has done this please get back to me. Tony.

48tony said:

My main concern with this high ohms reading is it possible for it to cause my rectofier and coil to burn out prematuerally ?

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No, the higher resistance will not cause anything to "burn up". If your rectifier "burned up", the likely cause was too much load on it. By too much load, I mean too much current flowing through it to the battery and boat harness.
I look at the health of the battery first. If it is aged, if it takes more current to charge than a good battery, if it takes longer to charge than a good battery....those are all situations where the rectifier has large current load, over a long period of time. Heat inside the rectifier builds, blows the diodes inside.

An aside.....the resistance measurement of a stator coil is almost useless. You are basically reading the resistance of a coil of wire. .75 ohms is virtually a dead short, as it should be on any alternator coil. And your reading of double that is simply a design difference in the CDI part vs the OEM part.

kimcrwbr1 said:

For you to be getting those high voltages it just sounds like a mismatch with the stator and flywheel.

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Where did he post a voltage measurement?


OP, I would REALLY like you to post exactly what CDI tells you. I want to know if it is different from what I told you.
Thanks in advance.

Daselbee Im glad you had the info i needed for this new cdi stator.I think I will still call cdi and ask a few qustion .Maybe they have one on ther shelf just to test and if it has the same reading of 2.0 I will feel better and put it back on and have a oem stator for a back up if this cdi stator ever craps out.And as for the battery I have it is a non maintence free ultra power cca-650.My book battery specks call for a 300-cca.The batt Im running is new and mariane grade.I think after I put a regulater on it Ill be good to go. It has been told to me that these newer batt just cannot leak the extra voltage going to them and they get cooked unless you put a draw on the batt lights,fishfider,radio ect.Butt to me I want a correct fix and the new cdi rec/reg is what i need to fix the problem. Tony

On the older engines that have a non-regulated rectifier, it is common for the voltage to go up towards 16, 17 volts. There is no regulator to hold it down to the 14.8 normal charging voltage. Plenty of guys put the new fish finders, depth gauges, etc on, and the electronic device flashes warnings to them regarding over voltage...then they post...

But anyway, Tony, a rule of thumb.....when an electrical device burns up, it is because it has been loaded too much.

JUST A RULE OF THUMB!!! Surges occur that blow stuff, but if you think about it, a surge is a very quick overload....

So, I still think that if you are burning up rectifiers, there is too much load on it's output for too long a period of time.

If you feel comfortable with it, rig in an ammeter to the rect output. That would tell the tale right there.

Get a cheap ammeter, say 20 amp rating, disconnect the red rect lead from the term strip, connect that red lead to one side of the ammeter (the + side), connect a wire to the other side of the ammeter (the - side), and then connect the other end of that wire to the term block that the original red wire came off. Do not use a DMM to try to measure amps unless it reads up in the 20 amp range (most are 10) and UNLESS YOU ARE SURE HOW TO ATTACH THE LEADS for ammeter operation. You usually have to change the red meter lead to a different meter socket on the meter.

Wire it in series with the red rect. output lead if that makes more sense.

Start engine, observe amperage. If it is charging at 9 amps, the system spec, it can probably take that load for a short time, but it will eventually give up and fry. Also, you can feel the rect...if it is hot, you can be sure it is relly loaded. Also, if the system is outputting 9 amps, you are putting a very heavy load on the ststor charging coils. That will cook a stator after a period of time. Start melting the insulation, etc.

I really would like to know what CDI says.

if he has the right stator on the engine then the regulator will fix the problem....putting a new rectifier on it will work for a while..maybe a month..maybe a year but its going to fail....there are two indications of the problem..the voltage will read high...and the tach will start to read funny....it may read too high or too low or do both....eventually it wont read and you look down at the meter and you are not charging....on the rectifier only systems this rectifier is normally mounted on the block...it needs the block for a heat sink as it normally runs hotter than the block...tony has another entry in here on that motor and in it i posted a url for a good writeup by haffiman on the subject...this site must avearge a rectifier problem a month on evinrudes and its a known problem on non regulated charging systems.....they just will nor take the marine batteries that most of us use today....