Alternator Woes

rafiki_

rafiki_

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Final prep for Rafiki's Safari to Southampton, and stb engine alternator not charging. Thought it might be the drive belt, but no such luck. No voltage out of the regulator. Any thoughts?
 
Is there any AC input to regulator? Maybe the regulator, but equally could be windings etc. Is the regulator removable in-situ? Most car versions have to come out anyway in my experience due to poor access and most boats are probably worse! Depending on cost, probably easier and quicker to change it...
 
Just to add to my earlier, tach is driven from the ac windings, if tachometer works but no charge then the regulator, if no tacho then possibly an issue with the power to the alternator, check the pop out circuit breaker on the box at the back of the engine, on mine it's blue. Just so happens I upgraded both alternators so old 55A units are sat in my shed, you are welcome to one if you want a second hand one.

John
 
rafiki_ said:
Final prep for Rafiki's Safari to Southampton, and stb engine alternator not charging. Thought it might be the drive belt, but no such luck. No voltage out of the regulator. Any thoughts?
Click to expand...

Sorry to hear that P. When I had a prob with the regulator on one of my alternators, it transpired that you couldn't separately access the regulator and the entire alternator had to be replaced. The OE manufacturer was Mitsubishi and it was significantly cheaper to buy it from an alternator specialist using the Mitsubishi part number than from VP. Best of luck with it.
 
jimmy_the_builder said:
Sorry to hear that P. When I had a prob with the regulator on one of my alternators, it transpired that you couldn't separately access the regulator and the entire alternator had to be replaced. The OE manufacturer was Mitsubishi and it was significantly cheaper to buy it from an alternator specialist using the Mitsubishi part number than from VP. Best of luck with it.
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Many thanks Jimmy. Not sure what make, as the engines are Cats. Likely to be USA supplier. Regulator looks like it comes off the alternator. Advance, the local Marine Techies have the alternator, and will get it tested in the morning. Planned to lock out at 10 am tomorrow. Looks like this will slip to Wednesday. If this happens, the trip is still doable, as the wind low around Land End on Thursday. Blowing up Friday and Sat atm, so need to get round before then.
 
Spare Thyme said:
Just to add to my earlier, tach is driven from the ac windings, if tachometer works but no charge then the regulator, if no tacho then possibly an issue with the power to the alternator, check the pop out circuit breaker on the box at the back of the engine, on mine it's blue. Just so happens I upgraded both alternators so old 55A units are sat in my shed, you are welcome to one if you want a second hand one.

John
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Was getting 15v to the alternator. Don't dispose of your spares yet please��
 
It could be, the only time I have seen the same symptoms is when I have started the starboard while the geny was still powering the charger, I think it's because the charger holds the voltage high so the alternator regulator gives up trying to charge, the exact symptoms you are seeing, tacho works for a few seconds, then the lower charge light comes on and tacho goes to zero.

I guess what could be happening in your case is the brushes may be a bit worn, could be worth pulling the regulator and brushes and having a look, problem is the starboard is a pig to get at. When I changed the alternator the only way I could get down the hole far enough was to remove the complete starboard seat, I could not get deep enough just going through the seat hatch under the cushion. You should be able to get Prestolite parts at Dingbro, that's wher I got my upgrades, the marine alternators have an extra seal between the regulator and brushes, the part numbers I gave you are the marine type.

Let me know if you want me to ship one of my spare alternators

John
 
Spare Thyme said:
It could be, the only time I have seen the same symptoms is when I have started the starboard while the geny was still powering the charger, I think it's because the charger holds the voltage high so the alternator regulator gives up trying to charge, the exact symptoms you are seeing, tacho works for a few seconds, then the lower charge light comes on and tacho goes to zero.

I guess what could be happening in your case is the brushes may be a bit worn, could be worth pulling the regulator and brushes and having a look, problem is the starboard is a pig to get at. When I changed the alternator the only way I could get down the hole far enough was to remove the complete starboard seat, I could not get deep enough just going through the seat hatch under the cushion. You should be able to get Prestolite parts at Dingbro, that's wher I got my upgrades, the marine alternators have an extra seal between the regulator and brushes, the part numbers I gave you are the marine type.

Let me know if you want me to ship one of my spare alternators

John
Click to expand...
John, many thanks for this. Alternator off and being tested this morning. Will let you know the outcome. I would be happy to take one of yours as a spare in any case. Could you PM me with cost please?
 
This is exactly the fault I had on my AD41P a few weeks ago...your symptoms are identical.

A new alternator fixed it in 15 mins. The one I took off was not a VP but a 90A from a Bukh.

VP was £370 for a 50A...the one I got was £145 for a 90A.

Very easy to replace as well.
 
sorry to hear that P, looks like it's an easy and not too expensive job replacing the alternator.

I was just wondering if effectively having a generator means that you can overcome alt problems (temporarily)
I mean you could even go from A to B and run the genny together with the engines so that the batteries are properly charged with a dead alternator, or am I missing something?
Even more so with solar panels and smaller engines (sailboats with no wind fe...)

cheers

V.
 
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Sorry to hear of this trouble Rafiki. I was thinking same as Vas: why delay the trip just because of a bad alternator? You have one good alternator plus a genset/battery charger, so you're good to go while the weather is suitable, aren't you?
 
If its the same as mine when it failed he will have the alarm going off all the time and no rev gauge for one engine..which i personally don't like.
 
rafiki_ said:
Yep, as per SailorSam, annoying alarm, no tachometer or pas, so best to fix here. Is ok to use the gennie while at speed?
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fair enough, didn't thing of the annoying alarm noise :eek:
If the skin fitting is nicely placed and there's a decent flow of water to the genny strainer, I don't see what would be the problem

cheers

V.
 
rafiki_ said:
Yep, as per SailorSam, annoying alarm, no tachometer or pas, so best to fix here. Is ok to use the gennie while at speed?
Click to expand...
Pas? power steering? Confused ere! OK I get the annoying alarm point though.
Yes we run gensets very often when underway, sometimes 10 hours/day non stop. Plenty of boats (MYAG's for example) need gensets the whole time while underway. Perfectly normal
 
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