High Voltage from Merc ?????

[murdmerc]

Engine Details : Mercury 40HP 4Cyl. Classic 2-Stroke 1991
Model : 40 PTTO Serial : 09682741

Boat out of the water for a couple of years old fishfinder replaced and New VHF and Plotter fitted
Now VHF and Fishfinder reporting Excessive Input Voltage - When I found out about the issue the multimeter readings at the battery were :

Engine Off : 13.5V
Egine On Idle : 16.5V
Engine On 3000+ RPM : 18.8V

When I removed the rectifier the +VE ring terminal was pretty melted into the plastic body and I also noticed the silicone filler was cracked all around the edge almost in a circle. I tested the Rectifier PN. 816770, no continuity shown between terminals A,C and Ground tried both +ve and -ve lead to ground same results - Manual states to replace rectifier - which I did with this one of ebay : 135632 NEW MERCURY MARINE OUTBOARD RECTIFIER 62351A1 62351A2 816770 816770T | eBay

Last Night - before fitting the new one. I ran the same tests on it - Confusing Results, in that it also tested the same - no continuity shown between terminals A,C and Ground again tried both +ve and -ve lead to ground same results. I swapped out the rectifier anyway and ran the engine - same readings as before:

Engine Off : 13.5V
Egine On Idle : 16.5V
Engine On 3000+ RPM : 18.8V

I'm scratching my head at this point, then I followed one of the basic tests to test the stator - Mine is the Red 9A Type. Apparently readings on the Ohmeter between the 2 yellow wires should be in the range of 0.4 > 1.0 ohms. When Tested, due to capacitance "I Think..." its showed results decreasing from 1.1 ohm down to 0.3 ohms but in most cases stabilised around the 0.4 ohm point. I know there are other tests for Amps etc which can be carried out but Wasn't really sure how to do these.

While I was out on the mooring I happened to have with me a new Leisure battery I bought as a backup - I am eventually planning the dual batter setup with a Perko Selector switch. I remembered a couple of months ago while the boat was in the driveway that the battery box had filled up with water and covered the terminals (engine still connected) - Maybe that did something to the battery ?? Anyway I thought I'd try the leisure battery and after fitting it it gave the following readings :

Engine Off : 12.5V
Egine On Idle : 14.5V
Engine On 3000+ RPM : 15.2V

I went for a short run and even at W.O.T no instruments reported high voltage - Solved ! .... I thought

Today I was going to head out on another run and before I even got out of the moorings at 1300 RPM I got the dreaded "Excessive Input Voltage" Alarm on th VHF. Moored up again and put the voltmeter on the Battery - Readings as follows :

Engine Off : 12.5V
Egine On Idle : 14.5V > 15V
Engine On 3000+ RPM : 16.8V

I'm Really stumped now and not sure how to go forward - Looking forward to any suggestions

Diagram Attached of boats current wiring

 

[emckelvy]

Re: High Voltage from Merc ?????

Your system is unregulated and voltage will rise as you've observed. You can retro-fit a regulator from one of the models that came equipped with one. You could also be having issues with your battery, typically a maintenance-free battery doesn't work as well with an unregulated system. A good old-fashioned lead-acid battery with thick plates will usually work the best.

Here's an older thread with an excellent discussion on the issue:

http://forums.iboats.com/mercury-ma...-4cyl-electrical-system-regulated-584868.html

Here's an example of a regulator/rectifier assembly that could be retrofitted to your motor:

Voltage Regulator for Mercury, Mariner 8301792 815279T 815279-3 815279-5 883072T, MES 1784M - Sierra 18-5743 - iboats

You'll note it has extra leads, you'd only use one of the red wires and tape-off the other. The gray wire is tach output.

You might be able to find a deal on a rectifier/regulator on eBay. This Suzuki rectifier/reg, for example, would be simple to mount and hook up to your electrical system:

Suzuki Outboard Motor 1994 DT115 DT140 115 140 Voltage Regulator | eBay

Another eBay deal, this regulator-only was used on some Merc V6's and would "piggyback" along with your existing rectifier:

Mercury Rectifier | eBay

I've attached a picture of how this is supposed to be connected, courtesy of my Very Good Friend, Dr. Frankenmerc. A very simple setup and the eBay reg. comes with the wiring harness, Good Deal!

Last thought, one Very Low-Tech way of dealing with the issue is to leave your boat's running lights turned on. This small load may be enough to keep the voltage down to a level that doesn't bother your electronic gear.

HTH..............ed

 

[murdmerc]

Re: High Voltage from Merc ?????

Thanks for the reply - This is a relief to hear. Means all is running as it should and that I can sort the issue myself.

Am I correct in thinking that if I go down the route of fitting a 5-Wire type merc. regulator/rectifier it will actually replace my current 3 post rectifier ? (If So - does it matter which way round the Yellow wires go? Also which of the 2 red wires get used as they appear identical?)

Or will it somehow piggyback alongside my rectifier as your diagram of the merc. two wire regulator does ?


Thanks in advance

 

[emckelvy]

Re: High Voltage from Merc ?????

Thanks for the reply - This is a relief to hear. Means all is running as it should and that I can sort the issue myself.

Am I correct in thinking that if I go down the route of fitting a 5-Wire type merc. regulator/rectifier it will actually replace my current 3 post rectifier ?

Or will it somehow piggyback alongside my rectifier as your diagram of the merc. two wire regulator does ?

Thanks in advance

Depends on what you get. The rectifier/regulator assy completely replaces your existing rectifier-only assy.

Whereas the stand-alone regulator off the older V6 Merc would just wire-up in tandem with your existing rectifier, to accomplish the same thing (albeit in a different manner).

I just happened to stumble on the V6 voltage regulator a while back, and thought that was a pretty good way to fix the problem (and cheap, too for the used one).

My buddy Doc Frankenmerc has done both types of installations to the older Mercs and sez either way works great.

HTH...........ed

 

[murdmerc]

Re: High Voltage from Merc ?????

Thanks for the Info - I've actually just bough the old stand alone merc regulator on ebay - as you posted above.

In the meantime I've installed a 2nd battery to run the instruments which I'll have to charge manually avery so often until I get the regulator and dual battery setup properly.

Anyway while I was doing that I accidentally connected the Outboard cables to the wrong terminals on the battery and it sparked - Outboard still runs fine only thing is the rev counter was acting weird needle bouncing between zero and the actual revs, for an hour or so and after that it just stopped working, Have I actually gone and properly fried the rectifier now ????

 

[oldman570]

Re: High Voltage from Merc ?????

I had the same trouble as you with the high voltage messing up my electronics. After research I found that all the regulators mentioned were for the 16 amp stators and might not work on the 9 amp stator. I found that CDI makes a rectifier/ regulator for the 9 amp system, part# 193-5114, that can be fitted and work. Cost is usually $100.00 +, but can save you a lot more than replacing some electronics that and will not really solve the main trouble. I tried to get one here on Iboats but was not able to do so. I ended up having to call a CDI distributor and they recommended a dealer where I could order on from. If you would like that dealers number PM me and I will send it to you. The dealer is located in Wisconsin, or you can go to the CDI website and look up a distributor near you. And yes you have probably fried the rectifier. JMO
Oldman570

 

[murdmerc]

Re: High Voltage from Merc ?????

Hi All

The boat came out of the water for the season shortly after writing. The regulator I bought from the states never arrived a rectifier arrived instead ????

Anyway I've now (tonight) purchased the correct model 6-wire version Regulator Rectifier unit P/N: 883072T with long screws for mounting.

Photo of new Reguator in Post below (can only post 5 photos per post)

I'm a little confused though about connecting it up. Here's some photos of my current setup with rectifier :





And Here is some Photos of some poor dude with the same engine who's regulator rectifier went on Fire :







My concerns are as follows.

1. The two Yellow Wires look easy enough to connect - I guess it doesn't matter what order they're in Connectors are the same?
2. The Grey wire looks like I'll have to cut the ring terminal off my current loom grey and fit a bullet connector
3. 2 x Red wires - Only seems to be one connected to my rectifier - where's the other ?
- If I do find 2 red wires to connect to how do I know which one to connect to which (I assume both are different in this case)
4. The other guys engine doesn't seem to have a stator adaptor in the Electrical box and mine does (mines a red stator)
- Will this affect the changeover of rectifier to regulator/Rectifier ??
5. If I ever figure out the above - after seeing other guys regulators going ablaze - is it worth installing an inline fuse assembly to the main red wire if there is one ? and which one ? Picture of inline fuse posted below (Assembly rated at 30A with 25 fuse Fitted)

If I could get these 5 points cleared up I'd be a happy man - As usual I'm sure there's 20 more things I should know first - Thanks in Advance look forward to any input.

 

[murdmerc]

Re: High Voltage from Merc ?????

Additional Photos

New Reg/Rectifier on Order :


Worth Installing an inline Fuse - 25A ??


Maybe I need this wee wiring Loom listed as Part No. 813524A2
Part 51 shown in the Engine Electrical Box Exploded Parts Diagram :


Thanks

 

[wired247]

Re: High Voltage from Merc ?????

You arent going to charge over your stators ability to charge so putting a 25 amp fure there wont hurt anything. Just connect both red leads to the battery junction on your solenoid. The yellow wires you can hook up either way. They are AC on that side. Black to ground and grey to tach.

 

[murdmerc]

Re: High Voltage from Merc ?????

Nice One!

So am I correct in thinking that I can connect the both red wires to the Starter Solenoid +VE post via the strange little 3-Way red link cable ? So both are the same ? Why are there 2 - Is it just to double up on cable diameter for high loads ?

If so it looks like I need to modify the small red 3 way link with the correct crimps as mine is slightly different from the item 51 in the parts diagram shown above as I have 2 x Ring Terminals and 2 x Female Bullet Connectors, Think I might have to swap the ring out for a male bullet terminal to marry everything up.

Thanks

 

[wired247]

Re: High Voltage from Merc ?????

Those red wires may have been set up to feed into a harness or something else but if you are feeding everything off the starter solenoids + post anyway it doesnt matter . Both reds are 12VDC and feed into the same "grid". If you have the harness with the two reds use it their way but like I said it doesnt matter much. The yellows are just AC and it doesnt matter how they get hooked up either.

 

[murdmerc]

Re: High Voltage from Merc ?????

I'm wanting to fit a temperature gauge with the sender connected to the 1/8" NPT blank on the water jacket. I was just wondering instead of having to run a wire from the gauge to the sender on the engine - Can I use the TAN wire which emerges from the loom of the commander 2000 control?

As far as I can tell, at the engine end, it emerges from the loom as you can see in the picture - the only trouble is there is a bit of confusion on my engine as it looks like somebody has mis-connected the TAN female connector to the Brown with white stripe male bullet connector (you can't really see that in the photo though - sorry) I am assuming this is a mistake because as far as I know the Brown and white should be a trim sender wire for giving a signal to a trim gauge which I don't use ???? But I would also find it odd that a male bullet (brown and white) would otherwise just be dangling around loose ?

Some clarification on this would be great.

Thanks in advance.

 

[wired247]

Re: High Voltage from Merc ?????

If you arent using the gauge the brown and white wire doesnt have any power.

The tan wire IS the temperature sender unit wire . If you had a temp sender and a gauge they would use that wire to get electrons from point A to point B . You can do whatever you want with it.

 

[murdmerc]

Re: High Voltage from Merc ?????

Nice One - Thanks