Pontoon Boat & Deck Boat Forum

I need some help. We had the boat out this past weekend - no problems on Saturday or Sunday morning. We took the boat out again Sunday afternoon and after about 15 minutes of cruising at 4000 rpm, I got a message across the screen on the depth finder about high input voltage. I looked at the voltage gauge and it was pegged at 16. When took the motor out of gear, the voltage dropped back down to 14. But when I would put it in gear and start to throttle up to 2000 rpm, the voltage meter would go back up to 16 again. I turned on the NAV lights and that brought it back down to just a bit over 14 and when I turned on the docking lights, the volts came down to 14.

We have tested the battery with a gauge and it is reading the same volts that I'm seeing on the gauge on the dash (so I know the gauge is correct).

This is on a 2003 Yamaha 90hp 4-stroke.

Any help would be greatly appreciated.

The voltage regulator is not supposed to let it go that high. So I would look there. Just replaced mine on a Merc. It was not hard to do.

if the battery is reading 16 volts, the battery is no good and sulfated. I would try a known good battery first and if it's still high, then do the regulator. Don't run the motor with the battery disconnected.

cwag911 wrote:if the battery is reading 16 volts, the battery is no good and sulfated. I would try a known good battery first and if it's still high, then do the regulator. Don't run the motor with the battery disconnected.

I assumed he meant that it read 16volts with the engine running, not at rest.

jrolin1 wrote:

cwag911 wrote:if the battery is reading 16 volts, the battery is no good and sulfated. I would try a known good battery first and if it's still high, then do the regulator. Don't run the motor with the battery disconnected.

I assumed he meant that it read 16volts with the engine running, not at rest.

Yes, correct. The 16 volts was with the motor running and up to 2000 rpm. When not running or running out of gear, it was reading about 13-14. Would this still indicate a bad battery or bad regulator?

Fully charged the battery should be 12.6 volts without the motor running. I agree with trying a good charged battery and checking the voltage. The bad news is that it could be the regulator and it could have hurt the battery if it charged that high for a while. Easy enough to have the battery tested at an auto parts store. They usually will do it for free. I have a cheap battery load tester that I use to check them since I have so dang many batteries in my stuff.

Correct me if I'm wrong, but I believe a fully charged good battery should read close to 14.8 volts. I doubt that your battery is the issue, batteries always, always drop in voltage as they age. I've never known of one to go up in voltage.

This sounds like a regulator issue. The fact that it goes up with the RPM indicates that is tied into the charging system. Do you have an actual alternator or simply a charging coil under your flywheel?

I had what was thought to be a dead short in nav lights. The volt gauge would slam down to 0 when nav lights were turned on. Turned out my volt gauge went bad.

lakebilly wrote:Correct me if I'm wrong, but I believe a fully charged good battery should read close to 14.8 volts. I doubt that your battery is the issue, batteries always, always drop in voltage as they age. I've never known of one to go up in voltage.

This sounds like a regulator issue. The fact that it goes up with the RPM indicates that is tied into the charging system. Do you have an actual alternator or simply a charging coil under your flywheel?

A fully charged battery should be 12.6 volts without the motor running. With the motor running and the battery charged your voltage should be around 14 volts. After I have been running my stereo and blender at the sandbar my voltage will slowly climb back to 14 volts as I run the motor and the battery returns to a charged state.

http://www.windsun.com/Batteries/Battery_FAQ.htm
All Lead-Acid batteries supply about 2.14 volts per cell (12.6 to 12.8 for a 12 volt battery) when fully charged.

http://en.wikipedia.org/wiki/Automotive_battery
Quiescent (open-circuit) voltage at full charge: 12.6 V
Fully discharged: 11.8 V
Charge with 13.2–14.4 V
Gassing voltage: 14.4 V
Continuous-preservation charge with max. 13.2 V
After full charge the terminal voltage will drop quickly to 13.2 V and then slowly to 12.6 V

Thanks for all the feedback.

Well, after talking with several others, we think we have figured out the cause and affect of my issues.

On July 4th, my wife and I were out and I went to turn the NAV lights on but it "popped the breaker" on the panel for the lights. I reset it and tried again and it popped again. I then noticed the wires for stern light that run through the Bimini frame, were being pinched when the top was open - to the point the frame had rubbed through the protective coating on the wires and now I had bare wires touching the frame. When I closed the Bimini top (bare wires were now not touching the frame), and the NAV lights came on - only the bow lights but not the stern light which is attached to the front bar on the Bimini instead of the back bar.

So what we all believe happened is when I tried to turn on the NAV lights, I grounded the system which would have possibly damaged the voltage regulator. But it just took it awhile to start having an affect.

Do you all agree with this theory?

When we bought the boat a few weeks ago, the seller mentioned they had just replaced that stern light after it got ripped off by a tree when he was towing it. So I think the wires were just not run correctly through the frame which left a loop of wire where the frame pieces touch when the frame is open. I can run them correctly to prevent that from happening again.

I went into IBoats' Yamaha Parts microfiche for your motor to see what it takes to change a voltage regulator.

These engines don't have alternators (as on an automobile), but a stator assembly mounted under the flywheel @ $547.

I have no idea what functions as a voltage regulator, none is listed. The stator has a couple of plugs that go into wiring harnesses.

As has been previously noted, the day of the shade tree boat mechanic are numbered. The day of parts pluggin' are over, as every single part on a modern outboard is outrageously priced. There's no substitution for knowledge--something I have little of on this subject.

I was looking for parts prices on my 2012 Yamaha 150 engine. Flywheel $1.1K, Stator $562, Starter $508, fuel injection pump $1.1k, power trim $1.8K. I think I need to start another savings account to accrue future repair costs.

Bamaman wrote:I have no idea what functions as a voltage regulator, none is listed. The stator has a couple of plugs that go into wiring harnesses.

Thanks. We found the regulator/rectifier (I've seen it called both), on the front of the motor under a protective cover. We can get to one of the bolts on the regulator/rectifier, but the other bolt is partially covered by the air filter assembly. It will take a pivoting rachet I think to get down to that bolt.

I'll post pics tonight.

We didn't think it was the stator since it is charging the battery. We have come to the conclusion that it is the regulator/rectifier since it is not "regulating" the amount of charge going to the battery.

jrolin1 wrote:

lakebilly wrote:Correct me if I'm wrong, but I believe a fully charged good battery should read close to 14.8 volts. I doubt that your battery is the issue, batteries always, always drop in voltage as they age. I've never known of one to go up in voltage.

This sounds like a regulator issue. The fact that it goes up with the RPM indicates that is tied into the charging system. Do you have an actual alternator or simply a charging coil under your flywheel?

A fully charged battery should be 12.6 volts without the motor running. With the motor running and the battery charged your voltage should be around 14 volts. After I have been running my stereo and blender at the sandbar my voltage will slowly climb back to 14 volts as I run the motor and the battery returns to a charged state.

http://www.windsun.com/Batteries/Battery_FAQ.htm
All Lead-Acid batteries supply about 2.14 volts per cell (12.6 to 12.8 for a 12 volt battery) when fully charged.

http://en.wikipedia.org/wiki/Automotive_battery

Quiescent (open-circuit) voltage at full charge: 12.6 V
Fully discharged: 11.8 V
Charge with 13.2–14.4 V
Gassing voltage: 14.4 V
Continuous-preservation charge with max. 13.2 V
After full charge the terminal voltage will drop quickly to 13.2 V and then slowly to 12.6 V

I stand corrected. Thank you.

The stator is fine. Sounds like you have a runaway regulator. When that happens the voltage will vary with rpm. The higher the r's, the higher the voltage. You might want to check the water level on your battery. Too much voltage can get the electrolyte boiling out & it can definitely ruin a battery (warp the plates). If the battery is still reading 12.6 & still cranks good, leave it.

A fully charged battery should read 12.6 volts, but it can read higher when just taken off a charger.

Thanks. Yeah we finally decided it was the regulator. I've got a new part on order - just waiting for it to get here so we can get back on the water. The good news, while we have it on the trailer at the house, we've power washed the carpet and did some spot treatments. When we uncover to do the new regulator/rectifier, we'll also clean and then protect the seats again.