January 20, 2023 at 6:59 pm #271507
1974 70ESL7 saw the old stator dripping rubber and decided to replace it and the rectifier. I replaced the old with a CDI stator and a Chinese rectifier. Took it out and ran it , putting out 15.3v
came home and ordered an oem rectifier , got it today and installed it. Same malarkey. Over 15v at 3800 revs. Scratching head. Battery is showing 12.4 v when I turn on the key. I verified it with an ohm meter. Even went to Napa and checked the battery . 660 cca battery , teats 580cca. Scratching head. I called CDI thinking output too high but called too late.
I’ve ordered a oem johnson service manual but it won’t be here until Jan 30th so until then I thought id ask for input.
US Member - 2 Years
Topics: 29January 20, 2023 at 7:13 pm #271510
If it has no regulator, then that would be normal. I am not a OMC guy but that was normal for older merc’s.
US Member - 1 Year
Topics: 50January 20, 2023 at 7:42 pm #271512
Agreed. It is normal. Thousands of them out there running around like that, including mine. Expect it might go even a bit higher.
US Member - 2 Years
Topics: 25January 20, 2023 at 7:43 pm #271513
I was always under the impression that the OEM alternators were only 7 amps and COULD’NT put out that kind of voltage thus they only had a small rectifier. Not sure what amperage the CDI stators are but can’t be that much bigger can they? Have you tried a different volt meter?January 20, 2023 at 8:22 pm #271514
Voltage and amps are two different things…
you coud can always install a rectifier regular for a flat voltage. that way some eqpt like depth sounders won’t turn off due to high voltage
Joining AOMCI has priviledges 🙂
US Member - 1 Year
Topics: 50January 20, 2023 at 8:24 pm #271515
The rectifier that came with those motors did not provide any voltage regulation. However, CDI now makes a REGULATED RECTIFIER for people that just stand to see 16V as normal. BTW, the factory service manual says to just turn on some lights.January 20, 2023 at 10:03 pm #271517
Well when I had it in the water last week, the voltage display on my Garmin 740s read the same as the dash bolt meter. Today I checked the voltage at the motor and the battery and both were the same as the dash 15.3. My concern is I’ll dry the battery and have a meltdown while out fishing.
I’ll call CDI MondayJanuary 20, 2023 at 10:04 pm #271518
Won’t it dry the battery?January 20, 2023 at 11:18 pm #271523
millions of motors work the same and no issues. ….
Joining AOMCI has priviledges 🙂January 21, 2023 at 6:33 am #271526
I had an old 1971,125 hp Johnson, that used to do the same thing. Back then, there WAS no optional regulator.So, I used to watch the voltage and run the power tilt in the down direction, occasionally to knock the voltage back down. You just need to add some more fishing equipment and lighting, to get it under control. You probably only need to find about five more amps. (You have the opposite problem from the Apollo 13 crew!)
Long live American manufacturing!January 23, 2023 at 10:46 am #271629
Well I spoke to CDI and like some of you said he wouldn’t really worried about 15.3 V. But if it was concerning they had a regulated rectifier that would hold it down somewhere around 14 14 1/2 V. So that’s what I did I order the CDI regulated rectifier.
This seems foreign to me because I’ve had boats all my life and I could always look at the voltmeter on my Suzuki’s, or my mercury. Verrado’s end they’ve always held a voltage about 13.2 volts . I guess that’s the difference between old old motors, and the new motors that are being produced in the last 20 years. Thank you all for your replies.January 23, 2023 at 12:15 pm #271633
happy ending 🙂
Joining AOMCI has priviledges 🙂January 23, 2023 at 5:09 pm #271649
13.8 used to be sort of the accepted “ideal,” but these days, I see 14 to 14.5 on new engines all the time. I personally don’t like 15 and above, either. If I had a boat with that reading, I would be trying to find out why.
Long live American manufacturing!January 23, 2023 at 5:29 pm #271657
Yeah the 15.3 kind of freaked me out a bit. I replaced all the electrical components and the wife wanted to go boating so we went and dropped it in the water and everything was “normal “ until I looked down and saw 15.3 on my volt meter and then checked my garmin 740s and it verified the voltage. I’ll install the regulator/rectifier this evening and check the timing and then give it a try.
Update; Worked like a charm.
January 24, 2023 at 5:16 pm #271681
- This reply was modified 1 week ago by Txgunslinger.
Funny, usually the Garmins on our boats under-rate the actual voltage entering the unit by 1/2 to one full volt. It makes for some semi-hetaed discussions between the electronics techs and the engine techs at the boatyard. Like, say there is 12.5 at the back of the unit. The display might say 11.5, which leads the electronics guys to tell us a reported electronics problem is a problem with the boat, not the electronics……
Long live American manufacturing!
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