Blown regulator/rectifier module on 90hp Suzuki

A

anchorout

New member
During my south Florida loop trip, the regulator on my Suzuki 90 failed, allowing 14.5 volts to the battery at all times. The engine only has 300hrs on it so I have to question the cause, besides the obvious "fetal mortality". I just installed a Lewmar 700 windlass, hooked across the starter battery. Is it possible that, with the engine running, the windlass is pulling enough current to damage the regulator? The battery was never allowed to run low. Seems like a long shot, but as I have made no other changes to the circuits, this seems like the only cause.

Question is has anyone else had similar problems from their Suzukis.
 
What was the alternator output voltage before you installed the windlass? At what RPM does the voltage go to 14.4 volts? How are you measuring the voltage? Have you measured the amperage output?

Have you checked your batteries? Specific Gravity? Have they been allowed to discharge under 50% (resting voltage lower than 12.2 volts). How old are the batteries. Have you checked the electrolyte level?==what is it?

Not sure what you mean by "hooked across" the battery. I assume that you put in the switch, contactor and circuit breaker. The windlass should not draw more than 50 amps, and it is normal to run the outboard when using the windlass.

I have had outboards which put out 14.4 to 14.5 volts "normally".
 
What did the old one look like when removed? Any obvious signs of heat damage, hot spots, bad connections?? Is one side water cooled?

In general terms, high voltage will reduce and or damage batteries, damage any electrical devices designed for 12-volt nominal operation esp if not protected internally and shut off.

and Dr Austin has excellent comments as always
 
Just as added info, I'm pretty sure my Yamaha 80 puts out 14-15 volts normally (which is also indicated in the specs). So that alone wouldn't make me think anything was wrong, at least on my engine.

Again this is Yamaha specific, but on my engine the regulator/rectifier was a known weakness. I bought a new one, installed it, and kept the still-functioning original as a spare. The new one was quite a bit beefier, larger heat sink, etc. Of course this was Yamaha.
 
Journey On has a 150 Honda. When the batteries are charged and the engine is running, 14.5 volts is normal. I just check the water level frequently.

The parts diagram shows a regulator so it must regulate, but it's set quite high.

Boris
 
Thanks all for your timely suggestions.

Let me be more specific. When I start my engine, it outputs 14.5 volts across the battery. That only changes when I stop my engine. When I do stop, the battery has been charged to that voltage. (Same reading on two meters.) My thoughts are that the motor is putting out its max unregulated voltage.

A couple of you tell me that your motor always outputs 4.5 volts. I am at a loss, as my motor, until this trip, always settled down and regulated at a much lower voltage. Before, when I shut the motor off and switched the solar panels on, I was usually at 12.8 or a little higher. Now the batteries are so overcharged that the solar can't input current. My motor must regulate differently than yours.

To isolate the battery from any other boat circuits, I took a fully charged battery and hooked ONLY the motor leads to it. As it was fully charged, I expected the motor to output, after a short period, a maintenance voltage. Engine running, output 14.5 volts. I think this proves that the regulator is shot. Also, it Ohms out as bad compared to the shop manual. To answer your question, there is no visible damage, melting or expansion of the regulator (That would be to easy). But I think we can assume that my regulator is bad.

The question is what blew it. The windlass is wired neg to neg and pos to pos from the starter battery through the breaker, across the relay, and to the windlass motor. It works fine.

The starter battery seldom drops below 12.6 volts, so I don't think the regulator is being taxed with heavy charging at the same time as sending amps to the windless. So, if you guys have the same setup on your windlasses, (I remember Bob does.) and have had no problems, I am at a loss as to what caused the problem, save untimely regulator demise.

By-the-way, this isn't the first trip that I have used the windlass, but the windlass is the last thing that I changed on the boat. That is why it was suspect to me.

I have a regulator on order. I am leery of changing it out, without any other changes, so any suggestions would be appreciated.

I'll check specific gravity ASAP

Thanks again!
 
My 05 yamaha f 115 also blew its regulator . about 6 years ago.it was covered under 6 yr warranty that I had . The yamaha dealer had them in stock so it must be something that goes .
if you are seeing your voltage going over 14.6 or so put on all your electronics to bring down the voltage and take it in to dealer or someone that knows how to track done electrical problems good Luck with your Suzuki Jim
 
I'm not sure if I was clear, but when I replaced my regulator/rectifier, it wasn't because of the 14.x volts it was putting out (Yamaha lists that as normal). It was because it was a known weak point (it would burn out) and since the new one was a better (superseded) design I wanted to replace it on my schedule, not out on the water somewhere. The new one is much beefier and better, but the voltage output is not any different. It was more about heat shedding.
 
Remember Voltage is pressure and Amperage is the amount....

A voltage regulator will regulate the pressure from 13.5 to 14.5 volts ....a dead cell in a battery will allow the pressure to rise...15 volts plus..

Switching the batteries off with the motor running hurts the regulator..as they are looking at resistance to gauge the amount... an alternator does not know it's own voltage... it can charge as much a 300 volts for a very short time...it's the regulator that determines the amount and adjusts...

Yamaha regulators are the exact same as Mercury regulators....interchange and electronically the regulator does not know what motor it is mounted on...in the automotive trade there are several series of different regulators but I would guess small marine regulators are essently the same.... Yamaha regulators cost roughly $250 so I bought a pair from a Mercury on EBAY for $45 and one of them is working perfectly.....has for several hundred hours...

When the tach. dies it is telling you that the regulator just crumped.

Joel
SEA3PO
ASE Certified Master Mechanic
ASE Certified Master Engine Machinest
 
I do understand. I am fighting a non-existing problem. You guys have been a great help and I have learned a lot about OB motor chargers from you. After further research and your advice, there isn't a $%^& thing wrong with my regulator. It charges at 14.45 volts. Not being a multistage regulator, as on my last boat, that is what it is suppose to do. You have saved me a lot of trouble and expense and I thank you.

Why it was acting differently in the past will remain a mystery. Frankly, it was working fine then and it works as it should now. So, if the tack dies, then I swap the regulator. For now, I'll worry about something else!

Thanks again!
 
I dont know what caused the failure but the device gets very hot and has heat sinks and/or water cooled, carries a lot of juice and that is a recipe for failure or is a POS (design flaw) just waiting to fail I lost a lot of respect for some outboard companies to faulty components
 
One thing to watch for is electrolyte being boiled off from the battery. Generally 14 to 15 volts will not harm the battery, but feel the case, if it is getting hot, or there is boiling (and loss) of electrolyte (water), then you may consider an upgrade to the regulator.

CDI makes an after market Regulator
 
Thanks for the info, Bob. That should have been a flag that nothing was wrong, the batteries were not using any water( no gassing). Live and learn.
 
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