Westerbeke low voltage

My Westerbeke 12.5 KVA, brushless generator is only putting out 102 volts. I have checked the rpm which is fine at 1850 no load rpm. The rectifier also checked out. The guide suggests hooking up a 12 volt battery and a bulb to check the diodes in place. This test indicates 4 of the 6 are bad.

My questions are....
Is this possible? I would have thought 4 of 6 bad diodes would cause a much bigger voltage loss.
Has anyone changed these out before themselves or is it time to bite the bullet and get a tech to the boat?
What could have caused the diodes to blow?

Any advice is appreciated!

"What could have caused the diodes to blow?"

Starting with loads already on the circuit makes some noisemakers very unhappy.

Best to start , let it operate for a min or two, no load , them put the load on slowly.

I assume you are talking about the diodes on the exciter rotor. I have replaced those before and even with one out of six failed, volts were very low. To confirm, I would unsolder one terminal at a time and test in open circuit configuration. Testing within the circuit is not easily done.

Did unit make proper volts up until recently?

Ski, yes it has performed perfectly until last weekend. The test for the diodes on the excitor rotor, using a 12 volt battery and bulb instead of a multimeter was meant to allow "in place" testing. I just think I must have been doing something wrong to have for out of 6 showing blown. Either something I did during startup or something in my testing procedure. These diodes are miniscule!

Those diodes just plain fail. When I was deep in generators, I kept a box of them. It is delicate surgery to unsolder them through that little access, but can be done. I would test in place, then if one was suspect, unsolder one terminal and test it in open circuit. Sometimes it would test ok then, sometimes not. Often I would replace that one anyway. Be very careful with polarity, sometimes the paint ring on the old one is hard to read.

Also, have you double checked the voltage with a separate meter? Boat panel meters can be sketchy. Check with DVM.

Westerbeke electrical ends don't seem to hold up as well as other brands. I have replaced numerous westy stator/rotors, got another one this week. I have replaced one Onan stator for like 10 Westy's.

And FF is right- Start under no load, breaker open, apply load small things first. When shutting down, run unloaded for a few minutes, breaker open, then shut down.

You may have a fault in unit other than the diodes.

Has unit breathed salt mist or got dripped on?

Rewind exchange units are available from Broward Armature in Ft Laud.

Dimer: Wish I could help, but it's beyond me...GOOD LUCK!

Thanks Ski, I will give it a go. Can't break something that's already broke
Wyoboater, you could come drink a cold one and give me moral support!

Wasn't able to make it to Bmt today, but, perhaps later this week. You had any luck yet?

Yes and no. Checked with OEM and the diodes are $33.00 each plus shipping. Went to the little local electrical shop, $0.78 each including shipping and they will be here tomorrow. Felt so bad I bought yet another soldering gun, 4 cans CRC which should last me 4 years and a flashlight.

That's too funny! Nice of you to keep local businesses going though.

Ok, cannot find a local generator tech locally that is willing to come to the boat. So I unsoldered (those things were welded in!) one end of each of the 6 diodes. All tested fine. Now I guess I need to test the actual windings. Not looking good. I guess I will be pulling the generator out if I need an exchange unit as can't see doing major surgery in the hole it's in.

That's really not looking good. Do you have a manual for it? Any other trouble shooting hints?

Sounds very similar to my problem a few months ago but my output was 92 volts

Broward armature sent me a rebuilt head and then stayed on the phone with me while I installed it

Dan the former owner still works there and was great

Thanks guys. I see a road trip in the very near future. I know of worse places than Ft L. Siestakey, roughly how much is an exchange unit?

dimer2 said:

Thanks guys. I see a road trip in the very near future. I know of worse places than Ft L. Siestakey, roughly how much is an exchange unit?

Click to expand...

Mine was 1186.58

and that included shipping

and shipping back for my core

Be certain of the voltage readings before you jerk it out. If rpms are good and volts confirmed low, I'd just do the Broward swap.

Besides the exciter rotor diodes and the bridge rectifier, not much serviceable in that thing. Even if you can find a tech with the proper test gear, that means you might find what the issue is, but the fix is the same.

Have you tried swapping the bridge rectifier cube? I think I had one that tested well but apparently was failing under load. Swapped and volts came back.

Hi Ski, yes changed the rectifier cube and checked all diodes. I have a tech coming tomorrow to check winding (he says he has a special machine?) and will help with the removal if needed. I will know for sure tomorrow if/when he shows up but have resigned myself to a road trip to Florida next week. Took the Jarvis Newman out for the day to make me feel better. It's amazing how well that works

dimer2 said:

Hi Ski, yes changed the rectifier cube and checked all diodes. I have a tech coming tomorrow to check winding (he says he has a special machine?) and will help with the removal if needed. I will know for sure tomorrow if/when he shows up but have resigned myself to a road trip to Florida next week. Took the Jarvis Newman out for the day to make me feel better. It's amazing how well that works

Click to expand...

Amazing how a road, I mean boat trip will cure most of your blues! We are anchored out tonight waiting on the Blue Angles tomorrow. It's the best stress reliever there is!

Capt, as a lowly private pilot, I stand in awe of the skills and reflexes those guys have. It is simply amazing. Enjoy the show tomorrow!

How'd it go with the tech? Any progress? And I totally understand taking Rhino for a spin.....boating cures the soul.

The tech has been a no show for three days. Latest promise is for tomorrow. So now that he has gained my full confidence, I will let him check the windings and then I will do the rest, which if it's what I suspect, will mean a quick trip to Ft Lauderdale for the exchange unit.

Dimer

although ours are not the same the price I mentioned included shipping and made it in 2 days

best of luck

Siesta

Siesta, I am in Beaumont! I have an excuse to go to Ft Lauderdale, with an overnight or two in Destin, another night or two in Lauderdale, Jacksonville on the way back, followed by a night in New Orleans, or two day shipping? Nah, you just can't trust those delivery guys......

HAHA

I like the way you think

At least it's gonna be a REAL road trip! Too bad about the tech though..in getting my fridge fixed I found out also how hard it is to get somebody you can actually trust to keep their word. Is your genny fairly easy to get out? Mine would be a first class PIA due to where the hatches are placed.

Well the generator weights 665 pounds. The bell end I am hoping....is only around 200 or so. I should be able to remove without a crane, we will see. Just have a lot going on right now (another good reason to get outta town for a few days).

Well, hope it all works out for you. We're leaving town Thursday or I'd offer my help....HONEST!

200 sounds about right for yours mine was 138

When are you going to be in this neck of the woods?

If a 12.5 BTD with alloy stator, I think stator is around 100lb. Rotor is pretty heavy, but comes off separately after removing stator. When sliding stator off rotor, be careful not to bump windings of rotor and stator against each other.

If the 12.5 WMD Winco end, stator is steel case and heavier. I think.

Pretty sure Broward will want both stator and rotor.