Voltage regulator / rectifier gone bad?

[frogman112]

I own a 2004 GTX that I purchased in 2014. I have bad no problems with it except the voltage regulator / rectifier.

When I first purchased it the previous owner had just installed a new battery. I soon discovered that the battery would drain down after several hours on the water. The voltage rectifier was bad and the 30A fuse mounted next to the MPEM (top one) was fried. I replaced both and the charge voltage to the battery was restored to spec.

After a couple of years the R/R went bad again. Fuse was good. Replaced R/R and charge voltage restored.

Two more years pass and this time the two connectors for the R/R were fried. I replaced the R/R and its connectors. Fuse was good. Charge voltage restored.

Now one year later and the battery seems to drain after a couple of hours on the water. The starter does not crank when shut off and started after about 5 minutes. Wait a few more minutes to cool off and it starts back up.

There are no P-codes that cause a beep nor are there any in memory. However, the red light flashes intermediately.

I keep the battery on a Battery Tender when stored. I placed it back on the charger when I got home and it took several hours to fully charge. Placed it back in the ski, base voltage 12.91V. Started engine and voltage increased to 13.88V. The fuse is still good but one blade has developed arc pitting (a multitude of small pits from electrical arcing).

Is it possible for the voltage regulator / rectifier to not be working when it is hot but work ok when it has cooled back off?

Is the arc pitting seen on one blade of the top fuse next to the MPEM caused by a bad R/R that allows A/C voltage from the magneto to travel into the electrical system?

I can not seem to find any information that describes the two separate fuses mounted next to the MPEM. What are these for?

My plan is to check all of the grounded connections that I can see in the harness next.

Frogman112

 

[Ckrawiec]

I'll take a stab at your questions:
1) it is always possible that an electric component will work improperly when it starts to heat up then seem to work perfectly fine once it cools down.....the question then becomes WHY is it heating up in the first place to a potential fail state?
2) The arc pitting on the fuse blade shouldn't be caused by AC voltage (since AC voltage is intercepted by the RR and converted to DC voltage BEFORE it hits the MPEM (that is the job of the RR anyway, as I understand it).
3) The 2 fuses mounted on the MPEM are for protection against OVER voltage to the infocenter guage (5 amp) and the voltage back to the solenoid (battery side - 15 amp)....IF I understand the system correctly

It would seem that your charging system is operating correctly, assuming the rectifier is putting out 13.88 VDC back to the battery...BUT I assume you are testing this in a static state of the ski (on the trailer perhaps).....I often wonder about what is going on inside the ski while under a dynamic state (with the ski bouncing around on the water).....I have yet to do this myself, but have you thought about watching the ski voltage situation while under running conditions? Make long leads with ring terminals to the battery and rig up a volt meter to those leads and tape it to the handlebars and see what the ski is doing while running about on the water....

 

[frogman112]

Thanks for your replay, Ckrawiec. Your explanation gives me a better idea of how the system works.

Yes, I am checking the voltages after returning home and on the trailer with the engine running.

Funny you should mention a volt meter. I was thinking on mounting one to the ski during the previous diagnostic episode but then got lazy when replacing the regulator / rectifier solved the problem. Sounds like I've been incentivized to go through with it this time. I mounted a volt meter to an antique car that I upgraded with some electronics such as a fan, electric fuel pump, etc. and it gives a good indication of what's going on and when.

I am also considering running a computer fan off of a small motorcycle battery to help cool the rectifier to see if it has any effect.

I'll update the post after having a chance to hook up a volt meter.

Thanks again.

 

[Ckrawiec]

Thanks for your replay, Ckrawiec. Your explanation gives me a better idea of how the system works.

Yes, I am checking the voltages after returning home and on the trailer with the engine running.

Funny you should mention a volt meter. I was thinking on mounting one to the ski during the previous diagnostic episode but then got lazy when replacing the regulator / rectifier solved the problem. Sounds like I've been incentivized to go through with it this time. I mounted a volt meter to an antique car that I upgraded with some electronics such as a fan, electric fuel pump, etc. and it gives a good indication of what's going on and when.

I am also considering running a computer fan off of a small motorcycle battery to help cool the rectifier to see if it has any effect.

I'll update the post after having a chance to hook up a volt meter.

Thanks again.

Good luck in your endeavors.....obviously, adding anything to the ski like auxiliary fans, batteries, etc....you will really need to consider HOW to secure those things in place UNDER OPERATING CONDITIONS as the ski will be bouncing around "violently" so anything not secured well becomes a projectile inside the ski.... think it through so NO accidents occur (battery acid spilling about the hull would not be a pleasant thing).

 

[gazzaskirepair]

How old is your battery ?
Batteries don’t last forever and are in the most worst environment to operate in
What ever you going to see while riding you can see by revingbthe ski in trailer with cooling hose pipe connected
Fuse could have pitying due being wet or humidity ( fuse cover seal not sealing )
A batteries internal resistance gets higher with age and draws more current to charge while riding
Get you battery load tested

 

[frogman112]

So, finally had a chance to get out on the water again this weekend.

Hooked up an LED voltage gauge to the battery with an on/off switch. Got the following results:

13.0 V after removing from Battery Tender and installing into ski.
12.8 V at boat launch.
13.8 V at start up.
14.0 V at 5,000 rpm.

Stayed at 14.0 V during entire two hour ride at various speeds. Started back up when hot. Red light on ski never flickered. Go figure.

After taking a closer look at how the R/R is cooled with the incoming air snorkel I've abandon the idea of experimenting with a computer fan to cool it. Probably have negligible effects.

My battery is only one year old and has been load tested. I had the older one in the front storage compartment just in case it was needed.

I checked the grounds for corrosion and they all appeared to have none. I cleaned them last winter as part of regular maintenance so I don't suspect this to be an issue.

I plan on having the ski out a couple of more times before the end of the season and will update the post in case anyone has a similar problem.

Frogman112