'84 50 hp 4cyl Is electrical system regulated?

Just replaced the three post electrical component on my engine with part #62351A2, which most vendors call a rectifier. (Engine serial # is 6540519)

At 2500rpm, the system voltage now rises to an amazing 17.4VDC. Before I replaced this part, it wasn't charging at all, i.e., the system voltage remained at 12.2VDC, same as it was with the engine off.

I am guessing that this engine was designed with an unregulated charging system.

This same little three post component is often described by vendors, eBay and others, as a "rectifier" but as often described as a "rectifier/regulator"

So I have two questions:

1) was this system designed as an unregulated system?

2) if yes, is 17.4VDC to be expected from a healthy charging system for this year engine.

Thanks.

Re: '84 50 hp 4cyl Is electrical system regulated?

I don,t know if this applies to your engine but if it does 17 volts may be close to too much at 7.5. Please read but you,ll need to know if this applies to your system Troubleshooting Mercury Battery CD Ignitions

******** This information is supplied as a service guide only. The information has been obtained from actual unit analysis, parts manuals, and other sources. ********


Recommended Tools:
For DVA: Fluke Multimeter with CDI #511-9773 Peak Adapter, (or CD-77)
CDI #511-9701 Battery CD Tester
CDI #511-9710 Trigger Tester
CDI #511-9766 Spark Gap Tester
Jumper Wires
A Reliable Volt/Ohm Meter (it the CD-77 is used for the DVA)
CAUTION; DO NOT USE A MAINTENANCE FREE BATTERY WITH THESE TYPES OF IGNITIONS AS THEY TEND TO OVERCHARGE AND BLOW THE PACKS.> Typically 17 Volts +.

Note: A large portion of the problems with the battery CD units are caused by low battery voltage or bad ground connections or high battery voltage. Low Voltage symptoms are weak erratic firing of cylinders. Misfiring after a few minutes of running can be caused by excessive (Over 15.5 Volts DC) voltage at the pack. - WARNING : Check the voltage on the red (or purple) wire at the CD unit through the RPM range. At no time should the voltage exceed 15.5 Volts DC.

Re: '84 50 hp 4cyl Is electrical system regulated?

My 1980 has a rectifyer but no regulator. I used to get 17+ and was nervous about my electronics so i got a rect/reg from a later model and put it on. Now I get a nice regulated voltage of about 13.7ish.

Re: '84 50 hp 4cyl Is electrical system regulated?

Thats what I was thinking too and posted a question asking the pros if the system tops out at 17 even if exceeding the max RPM recomended for the engine (Stator output)

Re: '84 50 hp 4cyl Is electrical system regulated?

Excellent, thanks. I too am concered about the fate of my electronics, to say little of the battery itself. When you installed a regulator from a later model, were you able to use one of the three posters, or did you use a more sophisticated model. in any case, a part number, or some identifying data would be very much appreciated.

In the mean time, btw, I use the two rather large "landing lights" on my pontoon boat to provide effective regulation of the voltage, but it's not making me a favorite among the littoral folk on the lake.

Re: '84 50 hp 4cyl Is electrical system regulated?

good info on the systems here http://forums.iboats.com/mercury-ma...system-without-regulator-question-584869.html

Re: '84 50 hp 4cyl Is electrical system regulated?

So I have two questions:

1) was this system designed as an unregulated system?

2) if yes, is 17.4VDC to be expected from a healthy charging system for this year engine.

Click to expand...

1) Yes.....
2) Yes and No as you are overcharging. Your engine has a 6 amp system at thats at WOT. You dont mention in your post as the type of battery you have but always use a non maintenance free battery with a minimum of 700 CCA. Maintenance-free batteries (gel cells / AGM / closed-case) have thin plates. They’re ideal for a charging system that maintains a typical charge between 12.5V – 14.4V, but not for outboards, where batteries are commonly drained by accessories i.e. when there is no charge applied to a battery while the battery is in use. The thin plates cannot withstand constant discharging and charging. It will develop weak and/or dead cells due to this
behavior. Its heavy plates can withstand constant discharging and charging. These batteries have much more reserve time and are much more suited for this behavior Here is a list of do and dont for these systems:
1) recommended type of battery for outboards is a single (NOT more than one) 700+ CCA dual purpose or cranking/starting non-maintenance-free battery.
2) NEVER allow the stator to charge a battery. The stator is designed to maintain the battery's voltage at an
optimum charge. It's not designed to charge a dead or weak battery
3) NEVER jump-start a battery while an outboard engine is running. This can cause damage to the rectifier
4) A rectifier’s job is to convert the stator’s AC signal into DC to charge the battery. In non-regulated applications
(rectifier only), the battery acts as its own regulator, which is not designed to do. When it can no longer self-regulate
proper voltage from the rectifier, usually due to dead and/or weak cells, it poses a serious threat to rectifier failure
and thus needs replacing.
5) Check all battery connections, particularly at engine ground. Make sure all connections are corrosion-free and tight. Do NOT use wing nuts. They will loosen over time due to vibration, causing battery and/or rectifier/regulator failures.
In your case since its overcharging this is what I would look for in this order: 1) connections 2) battery type/condition 3) stator. Measure DVA voltage across the stator's battery charge wires (typically Yellow wires) while connected to the rectifier. At idle, DVA should be between 17-25V DVA. If not, disconnect the yellow wires from the rectifier and retest for 17-50V DVA at idle. If not, the stator is possibly faulty.Also the check the DVA voltage from each battery charge wire (typically Yellow wire@1500 rpm)) to engine ground. The two readings must be within 1.5 volts of each other (i.e. if one is reading 20 volts, the other has to read between 18.5 and 21.5 volts). If the readings are not equal,place a mark across the connection between the stator and rectifier that measured low. Turn the engine off and swap the stator leads. Crank the engine up and retest. If same results the component that has the marked wire with the low reading is bad.....

Re: '84 50 hp 4cyl Is electrical system regulated?

As Fazt pointed out, only use a lead-acid battery as it is the battery that acts as the voltage regulator, holding peak voltage to an acceptable level.

Note that as a battery 'ages' the peak charge voltage will begin to rise. This is the voltage required to fully charge the battery, when charging voltage begins to near 16 it is recommended to take the battery in for a true carbon pile type load test to determine its real capacity as it may be nearing the end of its usefulness.

Re: '84 50 hp 4cyl Is electrical system regulated?

Further research as well as the simple, short answer from Georgesalmon indicates that the system is in fact unregulated, and that 17.4 VDC is to be expected from such a sytem.

The many offerings of that three post item on eBay and elsewhere that identify it as a "rectifier/regulator" are simply incorrect. It's a rectifier and only a rectifier.

The capacity of the battery to absorb the additional energy from 17.4VDC of input is an interesting issue. Battery technology since the time of this motor's manufacture has changed profoundly. A simple ole lead-acid battery with vented cells would have little trouble with it, but modern ones might -- and as ensign Georgesalmon notes, the more costly consideration might be the tolerance, or intolerance of ones electronic devices.

Anyhow, thanks to the backbenchers for, as usual, the most valuable information.

I would be curious to know, however, how a faulty stator could result in too much energy reaching the battery. Ditto for a bad connection.

Re: '84 50 hp 4cyl Is electrical system regulated?

I'd like to know how a faulty stator could make to much energy too. Since the stator is the only thing "making" electricity on an outboard motor where else could the "too much energy" come from? A stator is just a very simple alternator with magnets passing a coil of wire. As long as the magnets are still magnitized and the coil is not open or shorted it will keep making AC for as long as the motor is turning. On the other hand a bad connection could be open (no electron flow) or loose/cooroded and offer a high resistance (no or low electron flow)

Re: '84 50 hp 4cyl Is electrical system regulated?

George spelled it out, the stator makes electrical energy from the spinning flywheel magnets, the amount is dependant on RPM, the rectifier changes the waveform from AC to DC. A poor connection will increase resistance to the energy flow.

HOWEVER, a result of resistance is HEAT. Poor connections cause that connection to heat, sometimes red hot, melting wires and burning insulation. Sometimes when in or near a wire bundle it can start a seriously larger fire.

For this reason, some mechanics/owners, replace the rectifier 'bullet' style connectors with crimped and SOLDERED connections, making sure they well insulate their work.

Re: '84 50 hp 4cyl Is electrical system regulated?

There's lots of reasons to worry about high voltage in a charging system. But the question recurs: how does a faulty stator produce more voltage-- or energy -- than a good one. The fact is, it doesn't and it can't. If a bad connection presents a higher resistance to the stator circuit, the output of the stator, whether measured in watts or voltage will be less.

This old merc, through its stator and rectifier, furnishes a single phase, square wave DC to the battery and any components that happen to be connected to the electrical system. I have seen mine range as high as 18.1vdc. My pontoon boat has a couple of "landing lights" up on the bow that draw a good deal of energy, enough in fact, to lessen the system voltage to about 13.4 at any rpm over 1,000. So I usually turn 'em on when running the motor any longer than what is required to charge the battery from the most recent start.

The lesson in this thread is simple: if you're running an old merc with an unregulated system, it might be good to take some meaure to lessen the system voltage that is presented to the battery and to your electronic equipment.