Rectifier upgrade for 86 90hp I-6

[ejthomp]

I am going to replace the stock rectifier on this outboard as I'm not comfortable with the 16-17 volts I see occasionally on my electroncs. This stock rectifier just has 4 wires attached to three terminals, two yellow wires from stator and a red and a gray wire.

Any specfic suggestions on a quality, rectifier/regulator that will perform well (nothing over 14v), and hopefully install without too much difficulty without costing more than $100. I see some 5 and 6 wire units for $65, but they don't appear to be a brand name.

Also... I assume installation is straight forward.... Yellows to yellows...gray to gray...red to red and black to ground.... So, I don't want a six wire, right?

Also, I guess my stator puts out 9amps....right?

Anything I'm not seeing here?


Thanks!

On another issue, this outboard has been running well, but I am having some intermittent missing on one or possibly two cylinders that I just can't diagnos. The miss doesn't show up all the time and it often doesn't show up when the motor is first started. The last time out, I was running on plane about 3500 rpms for a couple of minutes when I could hear and feel the cylinder(s) drop out. I've learned that I can usually just go to WOT for a short while and the cylinder(s) will come back. Then the problem usually disappears for the rest of the day. I'm guessing this is an elctrical issue related to heat..... Any ideas? I almost wish te problem was consistent so I could troubleshoot it. Btw...new stator two years ago...

 

[AlKay]

Re: Rectifier upgrade for 86 90hp I-6

Good morning,

I had similar issues with my merc 500 Blue band. The two yellow wires are from the stator, red to battery positive and grey is to the Tacho as far as I know, Earth is via the body of the rectifier.

I gave up on trying boating places as none were able to offer a solution. I eventually looked into quad bikes as they use a similar system. http://www.miniriders.com/running-gear/22532-how-add-lights-charging-gpx-150-160-a.html , shows what I mean.

I managed to get a chunky 4 connector rectifier/regulator installed it on an aluminum cooling plate. Voltage never went over 14.5V. The grey wire just continue to the tach as it was before. I used one very similar to this, I figure for the $20 it was worth the experiment. http://www.motopartscenter.com/4pin...50cc-atv-dirt-bike-go-kart-scooter-p-802.html


The site I pasted above is just a google of '4 pin quad bike regulator' so you can see what I mean .


Hope that helps.

 

[ejthomp]

Re: Rectifier upgrade for 86 90hp I-6

The $10 ATV rectifier/regulator makes me a little nervous. Probably work just fine, but I have quite a bit of electronics I am trying to protect so spending a few dollars does not bother me if there is value.

How about this CDI unit? http://www.cdielectronics.com/AppGuide.aspx?Criteria=194-5279
or this Sierra unit ? http://outboardmotor11.blogspot.com/2012/02/sierra-international-18-5743-marine.html

If a rectifier/regulator is made for 16 amps or 40 amps, is there any reason I can't use it on my 9 amp system?

 

[canoemang]

Re: Rectifier upgrade for 86 90hp I-6

After my 2nd Mercury rectifier fried last year i went with the $5.00 radio shack rectifier.. Bought 3 and have 2 for a spare..

http://forums.iboats.com/showthread.php?t=477169

 

[AlKay]

Re: Rectifier upgrade for 86 90hp I-6

Hi again,

I think you will find, if you look at the original manufacturers, the regs can be far in excess of $10, I would stay away from a cheap one for long term use.

To protect the electronics, why not look sat what I have installed. It's called a Bucking Regulator. Small box placed on the power rail to the regulator. Anything in from about 9V to 30V, gives at steady 12.5V @ 10A clean supply. I run all my gear on that to make sure it's safe. Below is the unit I use http://cruisingelectronics.com/dc-6v-12v-24v-regulator-converter


Regards
Alan

 

[ejthomp]

Re: Rectifier upgrade for 86 90hp I-6

That's a nice idea, but with my wiring(multiple electronics, various locations) I would have to place that between the outboard and the batteries and use it to control the voltage into the batteries from the rectifier. Possible, but may not be my best choice since the cost is similar to an upgraded rectifier/regulator anyway.

 

[AlKay]

Re: Rectifier upgrade for 86 90hp I-6

Yeah , it's not really designed for that, mine is on the battery out to front for all instrumentation.

Regards

 

[gwukena]

Re: Rectifier upgrade for 86 90hp I-6

Just get a proper regulator/rectifier made for your application. I tried to go the el cheapo route on my 83 115, using a regulator from a kohler engine as suggested as a post in this forum. After it went for a crap and went from full wave to half wave rectification I ended up replacing a stator, and two more switch boxes that were only two years old. So much for my savings

Gary

 

[ejthomp]

Re: Rectifier upgrade for 86 90hp I-6

Just get a proper regulator/rectifier made for your application. I tried to go the el cheapo route on my 83 115, using a regulator from a kohler engine as suggested as a post in this forum. After it went for a crap and went from full wave to half wave rectification I ended up replacing a stator, and two more switch boxes that were only two years old. So much for my savings

Gary

Thank You for the warning. This is my greatest fear! So now...can someone tell me what the "proper" one is? I've found lots of them, but don't know exactly what I'm looking at.

 

[oldman570]

Re: Rectifier upgrade for 86 90hp I-6

As long as stator is only nine amps you can use most all Merc spec, 3 term, rectifiers for your motor. Merc also has 15 and higher amp stators and will burn out rectifers that are made for less amps. I would stick with rectifiers made for your motor or aftermarket that are. Cheap is not the way to go on somethings.
Oldman570

 

[ejthomp]

Re: Rectifier upgrade for 86 90hp I-6

Looks like I'm going to go ahead with the CDI unit.

http://www.cdielectronics.com/AppGuide.aspx?Criteria=194-5279

Recognized quality...used on all the later model Mercs so I assume it will be okay for mine. I wish the dimensions of the things were shown somewhere as I have to find a good mounting location for it.

 

[ejthomp]

Re: Rectifier upgrade for 86 90hp I-6

Well I ended up purchasing the Sierra Unit from this website.

http://www.iboats.com/Voltage-Regulator-Sierra/dm/view_id.174789

I just installed it and obviously screwed something up as I don't have a tach anymore. yellow to yellow (2 wires). black to ground, gray to gray, and one red to red.

I attached what I believe to be the red (+) line to the red wire and left the red (sensor) line unconnected.

I can't find instructions on this anywhere.

Help please!!!!

 

[ejthomp]

Re: Rectifier upgrade for 86 90hp I-6

Changed the red wires around and now I have tach back. I guess the red I thought was the sensor line, wasn't. Not sure I'm charging though... Why wouldn't it be? I rev it up in the driveway and I don't see voltage climbing on fish finder...staying about 12.4v....which is good I guess, but I expect to see it go up to about 13... hmmm... As part of this upgrade I installed two new batteries also as the old ones were almost six years old. Maybe the new batteries need a good charge... plus the motor running 1-2k rpm in the driveway can't be putting out very many amps.... I need to take it for a long run.

 

[oldman570]

Re: Rectifier upgrade for 86 90hp I-6

You can take a multymeter on DC volts accross the battery and get reading with everything shut off. Then start the motor and reading should go up to 14.5 volts or less for a short time then settle down to 12.5 to13.0 as the battrey gets recharged. You might have to increase RPM's a little but not over 1500 while on Muffs. Overcharging the battery is not good and should be avoided, as it will burn up eletrionics and battries. Make sure that the battrey is of the correct size for the motor and is a marine rated one for your motor as it could also cause trouble.
Oldman570

 

[Faztbullet]

Re: Rectifier upgrade for 86 90hp I-6

If you find it is not charging, make sure the heavier red wire is to constant 12+ and use the purple accy wire to small red wire as this will turn rect/reg on every time engine runs. You wont see much rise at idle as it is only putting out about 1-1.5 amps at idle on new batterys.

 

[ejthomp]

Re: Rectifier upgrade for 86 90hp I-6

If you find it is not charging, make sure the heavier red wire is to constant 12+ and use the purple accy wire to small red wire as this will turn rect/reg on every time engine runs. You wont see much rise at idle as it is only putting out about 1-1.5 amps at idle on new batterys.

I think you have hit the crux of the issue. There are two red wires coming out of this regulator and I only have one connected. I don't have a purple accy wire to connect to the "small red wire". Do I need to run one in order for this to work? Could I just connect both of the red wires from the regulator to the single red going to the battery?

 

[Chris1956]

Re: Rectifier upgrade for 86 90hp I-6

Normally the purple ign accessory wire would be on the motor somewhere. You are sure that motor is not a 70s model, where the ign accessory wire would be white, and the tach wire would be brown, right?

 

[ejthomp]

Re: Rectifier upgrade for 86 90hp I-6

Normally the purple ign accessory wire would be on the motor somewhere. You are sure that motor is not a 70s model, where the ign accessory wire would be white, and the tach wire would be brown, right?

Its a 1986... Had the stock 3 post rectifier with the two yellow from the stator, the one red and one gray from the motor connected to it. I am installing the later model Mercury 6-wire regulator/rectifier so I'm trying to figure out how to wire it in.

So, what you are saying is that I need to run a new purple/acc wire from somewhere on the motor to the red sensor line on the new rsgulator/rectifier.... That makes sense. The red + wire goes to the battery, but the red sensor wire actually turns the reg/rectifier on?

So both red wires need to be connected and that explains the issues I am having.

So... I've been looking around, but there is no purple accessory wire on this motor that I can see. I can find 12v red wires, but no 12v acc wire that comes on with the key. I find that wire up front on gauges and such, but nothing running back to the motor. On this outboard, what comes on with the key other than gauges? Must be something in back...... I guess I can run another wire all the way from the front....but I'd rather not...

Thanks for the hand holding.

 

[Faztbullet]

Re: Rectifier upgrade for 86 90hp I-6

That year model may only have the six wire harness which wont have the purple. You can tie the "small" red to the 12+ and it will be on all the time which wont hurt anything other than a couple of mill-volt battery drain.

 

[riptorn]

Re: Rectifier upgrade for 86 90hp I-6

All DC rectifiers work the same. The bigger the better for heat dissipation for high amperage. It is basically 4 diodes working together to convert AC to DC. On the 4 terminal rectifier there is 2 terminals for the AC input identified with the squirly s and the other two output with + and - . After that you could put a filter in to get a clean DC wave (Capacitors). As for increased voltage depends on the input AC volts. Don't know about the six wire but I would think to filter the DC wave. Hope this helps some.
Ps; There is two types of diodes. Silicon and Germanium. The Germanium diode is used in solar panels and wind turbines because of the drop in voltage.