Bad stator on '06 SX210 - OK to run rest of season before pulling to repair?

[srf32]

So, we have been enjoying our new (to us) '06 SX210 for the past couple of weeks on Lake Washington - working out a few kinks, getting to know the boat and pulling kids on kneeboard and tubes. Overall, we've been loving it and have had zero problems with the boat.

However, it has become clear the boat is not keeping the battery charged. Was fully charged when we pulled off the trailer, showing 12.6-12.7 volts at rest. Have put about 12 hours on it since (per YDS) and have watched as the voltage has steadily declined by a tenth every other outing or so. Now showing 12.0-12.1 at rest and starting to trigger error code 19 (voltage issue) at random times.

Purchased knowing the charging system wasn't a strong point of these boats from reading these forums, but we don't have a big stereo or any other accessories using much power, so that's what led me down the path that something isn't right.

Started troubleshooting and determined both rectifier/regulators are good (by swapping) and the connectors on both are in good shape with liberal dielectric grease when disconnecting. Checked stator coil resistance and both sides were good and neither had ground shorts. Then put the voltmeter on the stator coils and started each motor and let idle. Bingo. Starboard engine showing 20.3 to 20.7VAC across the three combinations. Port engine showing 2.4 to 2.5VAC across the three. Then disconnected the round, 3 pin stator connector and it was in good shape as well. Took voltage at idle again and still bad. Don't see anything else to check without taking off the front cover to expose the stator.

So here's my question. Is there any reason not to just disconnect the rectifier/regulator on the port engine and run the rest of the season letting the starboard engine charge as best it can. I'll find a way to charge while docked. We have dual battery setup and never use the second battery, so we'll have backup. Our outings are not all day - usually 2-4 hours. I believe with the rectifier/regulator disconnected there should be little to no risk of hurting anything.

Don't really want to pull the boat out now to replace the stator as 1) we have a short season in Seattle, 2) just got boat in the lake 10 days ago due to dealing with an unexpected medical issue, and 3) we got lucky and have use of a slip at our club this summer.

Anyone do this before or have any experience with similar situation? Thanks in advance!

 

[buckbuck]

I do not recall anyone reporting a stator not putting out correctly. You probably have more experience than most of us now. Please keep reporting back as to what you do as it will help the next guy.
We had one guy years ago put a truck alternator on the output of the engine. He just reported that it continues to operate without issue. Just a suggestion.

 

[212s]

That's odd...the stator is a very simple magneto generator and should never fail to produce proper AC output. I can see the rectifiers going, but not the magneto. Perhaps some corrosion managed to get to the coils or wiring and caused an issue. I would contact a dealer and ask if your proposal is ok till you can get it in for inspection.

As for normal output, these stators can put out about 25 amps from each motor when above 3000rpm, 50 amps total on a twin engine boat. That's a lot of juice to recharge a pair of batteries. We rarely have issues with low batteries after cruising back to the ramp for 15mins. I installed an on-board charger mostly for winter storage and during the week while at work. I don't bother using it on the weekends. If I had 1000w of amp power for the stereo, I would be more concerned. But my little JL MX500/4 amp doesn't draw that much unless I really crank it, and that's usually too loud for us.

 

[ripler]

Definitely the stator, I don't think there would be an issue making it the rest of the season letting one engine do the charging as long as you keep your batteries charged.

@212s I believe the MR1s only put out 14 amps each, if I'm remembering correctly.

 

[srf32]

Thanks for all the feedback. Did more research last night and have more confidence stator is actually bad based on symptoms and what usually causes them to fail. Plan to run without it until we pull the boat out later this summer and then will address. Will post an update as to our experience and what we learn.

Next step, research if anyone has ever propped up the front of a motor (after disconnecting motor mounts) and pulled the front cover to swap stator without removing the motor....

 

[buckbuck]

It may be just as easy to pull the engine out. You will have gone pretty far into the project already. Make sure you are careful with the shims on the motor mounts. This is from the high output MR-1, similar to yours.

 

[girthquake]

How were you able to test the resistance on the stator? Did you do it with a standard multi-meter or get the specialty harness?
Thanks

 

[WREKS]

@srf32 12.6-12.7 is not fully charged. Research this site for more info.

 

[ripler]

How were you able to test the resistance on the stator? Did you do it with a standard multi-meter or get the specialty harness?
Thanks

Yes standard multimeter, check wires to ground and then check resistance between each wire, 1-2, 1-3, then 2-3, the resistance values should be close. no special harness.

 

[WREKS]

@srf32 Regarding Post#8. Fully charged voltage is higher for a maintenance free battery. Just make sure it is not the battery! Replacing a stator requires pulling the engine and $400 for stator. If you do not already have them-Stator specs.

 

[srf32]

Just getting back online and wanted to post an update in case it's helpful for someone in the future.

Sorry for the long post, so breaking into two posts: this one about the electrical usage of our boats and the second about replacing the stator in the boat.

First, the stator was indeed bad, and there was no problem running with just one good stator for the season last year. Put about 80 hours on the boat and as long as we topped off batteries with charger between outings had no, real problems. It was clear the output of one stator was not sufficient to power both engines and keep the battery maintained.

At idle (both engines running), voltage would creep up to 13.1-13.4. While running at speed or at WOT, voltage would drop to 12.5-12.6. Only problem I had is the starboard engine would sometimes have a misfire right after pulling someone up, but if I backed the throttle back a bit for it and then eased it back up it would run fine. Still not 100% sure if this was voltage related since the starboard engine was the one with the good stator and I haven't had much time yet this season to recreate.

When first running this way I was curious about electrical power usage on our boats since there isn't much published about stator output. Had a current shunt resistor and did some quick measurements during an outing just out of curiosity. No precision claimed here, was just looking for rough numbers to get better understanding.

Port starter - 95-105 amps
Starboard starter - 85-90 amps
Turning ignition switch from "Off" to "On" (not starting) - 0.1 amp (Light load since fuel pump doesn't kick in until starter engaged)
Bilge blowers - 4.8 amps
Bilge pump - 1.0 amp
Didn't do lights as all LED now.

Port engine only running at idle (with dead stator) - 6.8-7.0 amps (consuming)
Starboard engine only running at idle (with good stator) - 7.0-8.1 amps (charging)

Then disconnected Reg/rec on starboard engine (so no charging at all) to see the electrical load of both engines operating.

Both engines at idle - 12.8-13 amps (consuming)
Both engines at WOT (8200 RPM) - 18.8-19.2 amps (consuming)

In hindsight, I should have measured current with the one stator working at WOT to get a better sense of stator output. But based on our experience I would guess the stator output is somewhere aroung 20 amps or a bit more based on the engine needing 19 amps to run and the voltage while running last season barely going above resting voltage at higher RPM.

Enough about electricity. Post on stator replacement to follow...

 

[srf32]

Part 2 - Stator replacement

Stator replacement was straightforward and simple to do without removing the engine.

I ozark-engineered a simple hoist by removing the seat cushions and laying a 2x4 across the bilge resting on the port and starboard compartment bases. Drilled a hole in the 2x4 directly above the lifting eye on the port engine and then used a long 3/8 threaded rod with a "hook" bent into it on one end. Flat washer and a nut and instant engine hoist.

Just lifted enough to hold the front of the engine after removing the motor mount bolts. I did have an issue with the motor mount bolt on the starboard side of the engine. It wouldn't budge and I couldn't easily get to it because of the exhaust elbow. I decided to remove the exhaust elbow and that gave me better access to be able to loosen the bolt. If you do remove the elbow, you'll need a new gasket where it mates to the exhaust manifold. It's YAMAHA p/n 6D3-14739-01-00. I bought the WSM equivalent on eBay for ~$30 delivered.

I was very careful to watch for and catch the shims under the motor mounts, but neither side had shims.

After that it was simply removing the front cover (remember to pump out the engine oil since the gear and idler behind the rotor are oil-bathed), cleaning and replacing the stator. I got the new stator on eBay for ~$65. I also ordered a new o-ring for the front cover (p/n 93212-04001-00).

All-in-all, pretty straightforward - probably took me 5 hours of total work time. Didn't know I'd need the exhaust gasket so took another week to get that part - otherwise would have been an easy afternoon project.

Inspected the bad stator and it appears the insulation had melted on one of the coils near where the wires are gathered to go to the harness. I also decided to replace the OEM shunt diode type Reg/Rec on both engines to a MOSFET version (Shindingen SH775). Cost me $200 for the pair and probably overkill, but should keep stator winding temps down since MOSFET regulators don't shunt to ground under light load.

Only had the boat out once this year for about 30 minutes, but now getting consistent 13.5-13.7 volts with both engines at idle and 14.0 to 14.3 at WOT. Will update after getting some more time, but looking good so far.

 

[srf32]

That's odd...the stator is a very simple magneto generator and should never fail to produce proper AC output. I can see the rectifiers going, but not the magneto. Perhaps some corrosion managed to get to the coils or wiring and caused an issue. I would contact a dealer and ask if your proposal is ok till you can get it in for inspection.

As for normal output, these stators can put out about 25 amps from each motor when above 3000rpm, 50 amps total on a twin engine boat. That's a lot of juice to recharge a pair of batteries. We rarely have issues with low batteries after cruising back to the ramp for 15mins. I installed an on-board charger mostly for winter storage and during the week while at work. I don't bother using it on the weekends. If I had 1000w of amp power for the stereo, I would be more concerned. But my little JL MX500/4 amp doesn't draw that much unless I really crank it, and that's usually too loud for us.

Just catching up after being offline a while. Thanks for he feedback. See my post above, but I believe my stator failed due to overheating which melted insulation and shorted/bypassed one or more of the windings.

Curious where you found the info on 25 amp output - I could never find any specs. That said, looks to be correct based on my (non-precision) measurements .

Thing to keep in mind though is the engines "eat" about 20 amps for the pair when running at RPM. So they are basically consuming most of the output of one stator.

 

[srf32]

@srf32 12.6-12.7 is not fully charged. Research this site for more info.

Thanks. To clarify, the boat came with deep-cycle marine batteries when we purchased it. Resting voltage (not maintenance voltage) for deep cycle marine batteries should be around 12.6V AFAIK.

 

[WREKS]

@srf32 Thanks for that clarification. Here are specs for 2007 SX230 HO. Your method for removing stator seems quite helpful.

 

[212s]

Just catching up after being offline a while. Thanks for he feedback. See my post above, but I believe my stator failed due to overheating which melted insulation and shorted/bypassed one or more of the windings.

Ok heat I can see causing a short...makes some sense.

Curious where you found the info on 25 amp output - I could never find any specs. That said, looks to be correct based on my (non-precision) measurements .

Found that from a post about Yamaha jetski's and the the specs seemed to confirm it, and they used the same engines in my boat. Makes sense they're the same.

Thing to keep in mind though is the engines "eat" about 20 amps for the pair when running at RPM. So they are basically consuming most of the output of one stator.

So 25 amps output, 10 amps "eaten" still leaves a solid 15 amps to charge PER ENGINE...that 's 30 amps to charge one House battery, makes sense as my batteries don't take long to charge up at all with twin engines. Granted I don't have massive amplifiers and speakers, just one small 500w amp driving stock speakers. I love it loud (classic and all rock music), but not for hours on end while floating, so I'll never have an issue with charging on my boat with the one small amplifier.

 

[Bruce]

@srf32 I am curious if you evaluated the SH678QA that Yamaha offers as an OEM replacement versus the SH775? I am having difficulty finding spec sheets for these.

I am planning an upgrade to LifePo4 batteries and thinking I should upgrade the rectifier / regulators as part of the process. Any advice would be greatly appreciated.

 

[srf32]

It's been a while and I don't recognize or remember the SH678QA Yamaha OEM part number you reference. Not sure if that is a MOSFET design or another version of a basic shunt diode / SCR design, so don't really have an opinion on it.

Also, I don't have experience with LifePo4 in this application, so not sure of voltages that battery will be happy with or how its BMS operates. My comments below are based on using traditional flooded cell batteries.

I chose to upgrade to MOSFET design to lower both the Reg/Rec temp and the stator coil temp since I had suffered failed stator coil due to melted insulation. My decision was between SH775 (35 amp) and SH847 (50 amp) RR made by Shindengen. Chose the 35 amp version after the power testing I mentioned earlier in this thread.

I probably have 100+ hours on them by now, and the RR's have worked great and never gotten too hot to touch the few times I've had the cover open after running hard.

If you're looking for more detailed tech info on MOSFET RR's, search for "MOSFET Regulator/Rectifiers - The Why & How" and you should find an informative post on the Honda SuperHawk forum.

Hope this helps.