Confused? Voltage Regulator vs Rectifier; Tach & Charging

Popeye_1990

Seaman
Joined
Sep 11, 2021
Messages
62
1980 Johnson 115 V4 2 Stroke

Greetings. I could use some input from people who know more than I. Every time I try to look up info about a voltage regulator for my motor I get returns on rectifier/regulator. These are two different components are they not? If they are as I believe, does the rectifier require the voltage regulator to work properly?

With that being asked, I bought a tach set it for 6 poles for my motor and it functioned one day. I pulled the rectifier and tested it and it read bad. I replaced the rectifier and the tach again functioned but only one day. I just pulled the new rectifier and it test good. The tach shows power (it's new) My motor starts right up and runs just fine. My battery shows charge at 12.5 volts. When I start the motor it only changes about 0.20 increase. Any idea where my problem may be hiding? Any input would be greatly appreciated.
 

Popeye_1990

Seaman
Joined
Sep 11, 2021
Messages
62
1980 Johnson 115 V4 2 Stroke

Greetings. I could use some input from people who know more than I. Every time I try to look up info about a voltage regulator for my motor I get returns on rectifier/regulator. These are two different components are they not? If they are as I believe, does the rectifier require the voltage regulator to work properly?

With that being asked, I bought a tach set it for 6 poles for my motor and it functioned one day. I pulled the rectifier and tested it and it read bad. I replaced the rectifier and the tach again functioned but only one day. I just pulled the new rectifier and it test good. The tach shows power (it's new) My motor starts right up and runs just fine. My battery shows charge at 12.5 volts. When I start the motor it only changes about 0.20 increase. Shouldn't it be more? Any idea where my problem may be hiding? Any input would be greatly appreciated.
 

Popeye_1990

Seaman
Joined
Sep 11, 2021
Messages
62
I merged it with this one
Go ahead and delete this one as well. I'm just an old man in a small town that has no marine service and I was just who looking for help. After I have thought about it, I feel you were overly curt and I don't feel welcome here. You can delete my account as well. I would do it but don't know how. I'll find help somewhere
 

Lpgc

Petty Officer 1st Class
Joined
Jun 17, 2023
Messages
258
Don't be in such a rush to leave Popeye, when I first joined I started a couple of threads about my (same) boat, moderators gave me a bit of a scolding and merged my threads, but the same moderators (also users of the forum) went on to help answer some of my questions. Nothing yoy wrote was deleted or edited, just merged into a single thread on the same subject, they do that to stop chancers repeating themselves in vain attempt to get maximum readership for themselves while spoiling the forum with repeated threads. Anyway, I'm interested in what you have to say and I'd bet there are thousands of other people here who'd be interested in what you'd have to say and help where possible. I'd like to add extra range to my boat.
 
Last edited:

saltchuckmatt

Commander
Joined
Jul 19, 2019
Messages
2,640
Agreed, and I'm one of those guys.

Rectifier.....it's main function here, an I'm not the best guy for this is to turn ac energy to DC energy. On outboards or ones like yours the battery is the regulator so it's important not to run without the battery.

The charging system is somewhat weak. At idle there nothing or next to nothing but put your probes on the battery and run the idle up and watch the voltage slowly go up.

When fishing every few hours I get my boat on a plane and zip to the next hole to get some energy back. Have 2 battery's is a must for me.

Your tach can have all kinds of issues and I'll let others comment.
 

1960 Starflite

Petty Officer 1st Class
Joined
Jun 23, 2011
Messages
377
I had overcharging problems with my 850 Merc. It would climb to 17 volts at 4k rpm, boiled the battery. I replaced the rectifier with a 6 wire regulator. 14.5 volts at any speed above 2k rpm. It has a Tach wire too. I had to get creative with mounting.
 

Crosbyman

Vice Admiral
Joined
Nov 5, 2006
Messages
5,439
sometimes diplomacy works a lot better ...I have seen a lot worse on this site and eaten crow myself and it became an acquired taste.

as to your question the the volt/reg 's job it to keep things (Volts) flat whatever the amperage load is as it charges the battery and feeds accessories.

A simple rectifier can't do that... it just takes the alternating +/- pulses from the stator and lines them up as a steady DC voltage for charging the battery and is subject to fluctuations as RPMs go up and down.

The battery being hooked up to it absorbs the fluctuations and doesn't mind because of all the store energy. If your rectified volt/amps can't keep up with the demand of accessories and engine the battery simply compensates as it " floats" its own stored power back out to the engine,s distribution " network" via the main solenoid power cable and out the the key B+ post for distribution to accessories connected to the "A" post of the key.
just look at the battery as a electrical "flywheel" :)

Rect /reg. are especially handy in keeping " flat" because modern electronic devices don't like fluctuation to the point of shutting down to protect themselves!

Years ago my Humminbird sounder and Merc 500 never got along due to high voltages !! I had to install a couple of small Radio Shack 12v regulators to feed it flat 12v. It never shut down on me after :)
 

Vic.S

Rear Admiral
Joined
May 4, 2004
Messages
4,718
1980 Johnson 115 V4 2 Stroke

Greetings. I could use some input from people who know more than I. Every time I try to look up info about a voltage regulator for my motor I get returns on rectifier/regulator. These are two different components are they not? If they are as I believe, does the rectifier require the voltage regulator to work properly?

With that being asked, I bought a tach set it for 6 poles for my motor and it functioned one day. I pulled the rectifier and tested it and it read bad. I replaced the rectifier and the tach again functioned but only one day. I just pulled the new rectifier and it test good. The tach shows power (it's new) My motor starts right up and runs just fine. My battery shows charge at 12.5 volts. When I start the motor it only changes about 0.20 increase. Shouldn't it be more? Any idea where my problem may be hiding? Any input would be greatly appreciated.
Sometimes the rectifier and regulator are two different components but often they are combined into one unit, hence the name rectifier/regulator.

A 1980 115 without power tilt and trim will have a 6 amp stator and just a rectifier. But a variant with power tilt and trim will have a more powerful (10 amp) stator and a voltage regulator as well as the rectifier. This is because without the voltage control of a regulator it would overcharge the battery.

If rectifier and regulator are working correctly you should see the volts rise to something around 14 to 14.4 volts at normal running rpm soon after starting the engine assuming the battery is already in a reasonably good state of charge. If you are measuring only 12.5 volts with the engine running at normal rpm there is something wrong. 12.5 volts will not charge the battery.
Check the voltage output from the rectifier and the voltage output from the regulator.
You may find the CDI Troubleshooting guide helpful in diagnosing the problem. https://www.cdielectronics.com/wp-content/uploads/2013/02/CDI Troubleshooting Guide - 2012.pdf

Take care to never disconnect the battery while the engine is running or you will blow the diodes in the rectifier.
 

film495

Petty Officer 1st Class
Joined
Apr 8, 2009
Messages
285
I've seen different motors some with separate regulator rectifier, some combined. rectifier converts AC to DC for the battery, and a regulator just cuts the max voltage to like 14.4 Volts so you don't overcharge the battery.

to test the regulator just put a voltmeter on the battery when the motor is running. If it say 18 or 26 or really anything over 15 the regulator is missing or not working. It it is jumping all over the place like crazy, the rectifier is bad or failing. If the volt reading is weak, the charging system has something wrong, bad connection, coil, something.
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,072
Take care to never disconnect the battery while the engine is running or you will blow the diodes in the rectifier.
Not sure how that is possible….you will however melt the windings in the stator
 

Vic.S

Rear Admiral
Joined
May 4, 2004
Messages
4,718
Not sure how that is possible….you will however melt the windings in the stator
If the battery is disconnected will the engine is running a high voltage peak can be produced. This is what blows the diodes.
Not sure why the stator windings would melt . That would require a high current flow
 
Top