Running with a faulty alternater ... OK?

[CarinaPDX]

As others have pointed out the loss of the alternator output may indicate imminent failure of something like bearings or diodes. It could also be a problem with the internal regulator; if that is the case this is an opportune time to remove it and replace with an external smart regulator. If I were in the OP's situation I would spend the time to remove the alternator and get it to an auto electric shop ASAP. Removing an alternator is about as fast and easy as a boat job gets - just be sure to disconnect the cable at the battery so that it is not live and looking for a short.

Fundamentally any question that is basically asking "Can I get away with not fixing ..." shouldn't be asked. Literally, in the time spent messing with this thread the alternator could have been removed, or at least well begun. Please adopt the attitude of keeping things working right and not waste time avoiding it.

I'm not meaning to offensive; this is just the wrong approach that years have taught me to avoid.

Greg

[more]

Originally Posted by team karst

OEM french alternator is around $700 USD. .

Whattttttt, in local shop price is around 100€ ebay 120€
https://www.ebay.com/itm/32482788901...0AAOSwXY9hZVUa

[team karst]

Yep. Thats the clone. But ur not fooled into thinking its a Valeo, right?

[more]

Originally Posted by team karst

Yep. Thats the clone. But ur not fooled into thinking its a Valeo, right?

and work not 110A but pump 80-90A

[Emmalina]

Originally Posted by team karst

That little cartoon is missing the D+ diodes. 9 in total. .

OK just for you LOL

[Boatyarddog]

Originally Posted by Kurlie1

"Silly post"???



Here was thinking this was a friendly forum


Actually nobody has answered the (silly) question ...



Lets rephrase it as simply as I can.


Does a faulty alternator (running via the belt) cause any problem with the motor.
IE... reduced h/power output ... drag on belts etc..
Or does it just freewheel quietly?

Well since you asked the question to be "answered" then, generally it's okay.

Belts and pulleys, run other "supportive" equipment, since you have two engines those systems run independently.

If the Alternator isn't smoking, back charging or leaking current when off, and the bearings in it are not dry or grinding, then it's actually probably need in the power flow for running pumps, or hydraulics.
If you not experiencing any thing out of the normal running and operation of your vessel, then that 1 alternator can wait.

I think the "silly" comment was about you asking a question you've already answered for 6 months without an answer.

My experience with this forum is that "silly" is flowery, considering what I've read.
Some are downright rude.
Go figure
Boatyarddog

[Cadence]

Originally Posted by Emmalina

Alternators have 6 diodes or more ! and three induction windings

OK, they are Y alternators so maybe getting better than half wave, still not what it should produce. I would guess a good shop could replace the diodes and he would be good to go at a fraction of the cost of new. I guess that depends on if there is a shop locally or if shipping is feasible option. I'd have bearing replaced since they have it apart anyway.
Most things a throwaway today but I don't believe this is the case.

[Boatyarddog]

Originally Posted by Emmalina

How does this diagram help or instruct the OP to solve his problem?
Could you include diagnostic information for them as well?
This info really tells nothing about the problem.
Thanks
Boatyarddog I

[Cadence]

Originally Posted by Boatyarddog

How does this diagram help or instruct the OP to solve his problem?
Could you include diagnostic information for them as well?
This info really tells nothing about the problem.
Thanks
Boatyarddog I

emmalina's showed one with collapse protection having zener diodes. It probably comes down to you get what you pay for? I would think a high dollar marine alternator would have that. An off the shelf auto one probably wouldn't since it wouldn't be needed.

[pcmm]

Originally Posted by smac999

Depending on how things are wired The port engine battery will Likly die after several hours of motoring. Then not start or run.

Why? The alternator provides no power that the engine needs. Your only power draw will be gauges.

[Captain Graham]

Interesting question lets see

1. What electrical power does a diesel engine need during starting?
You will need power to warm the engine with the glow plugs.
You will also need electrical power to spin the engine (starting Motor)
Both of these can consume lots of amps.
But you only do it once in a while and if you have enough solar panels and time between starts then no problem.

2. What electrical power does your diesel engine need while running?
Diesel engines normally do not need electrical power while they are running. They normally have a mechanical fuel pump and they do not have spark plugs.
But some like my Westerbeke Diesel have an electrical fuel pump so if you have an electrical fuel pump you will slowly drain the starting battery unless you have a way to charge the battery while running.

3. What other risks do you have with a faulty alternator?
As others have pointed out the real risk is the following
a. The alternator may develop a short and drain down your battery.
Simple fix just disconnect the electrical connection for the alternator.
b. The alternator bearing may fail causing the alternator to not spin.
This will distroy the alternator belt and if this belt is also used for your water pump or mechnical fuel pump then they will stop working.

[dbraymer]

1. Since these are diesels, nothing is gonna "die" until you run out of fuel.
2, If the engine(s) has a solenoid shut down valve, and you somehow run that isolated battery down to nothing, you may not be able to stop the engine with no 12 VDC available.
3. This setup should have a separation switch to keep the different engine batteries/alternators from conflicting with one another when everything is working right. This can be tricky, as connection can be caused by a shared load.
4. If one alternator fails (when the systems are separated) switching the engine electricals into "combined" mode should work pretty well, subject to cabling distances and switch efficiency. You might end up with one battery at 95%, and the other at 90%, for instance.
5. In combined (emergency connect) You might want to pull the wiring from the offending alternator, in case it somehow comes back to life and ends up competing and perhaps damaging the properly functioning unit. (or the solar regulator)
6. I would look the systems over carefully for separation between charging systems. The idea that "lets get everything charging everything at the same time" might not be so good. I have solar and the Balmar charging the house, and an independent alternator charging only the engine batteries. At the dock, I turn off the solar and allow the 3 stage dockside charger to bring all batteries to the same level. Before I go somewhere, the first thing is to disconnect the battery systems, and look at the voltage on the engine when running... (assuming it starts!)

[TMarvin]

Take a wire brush to all of the connections and put an anti corrosion grease on it. Mine was faulty this weekend (stopped working) and I looked all around town to get it tested (auto zone)or replaced and seemed ordering online was my only option. I came back to the catamaran cleaned all of the terminals and put it back in until I could order a new one. Just for the heck of it I started the boat motors to adjust the throttles and the alternator worked perfectly! Must have just had a little too much rust on a terminal.

[Dieseldude]

I would do a basic check of the alternator. Loosen off the belt and spin the alternator by hand. Do the bearings feel tight or gritty ? Can you feel any side play or excessive end play? Note that most rotating equipment has some residual end play, so a bit is normal, but it can get technical to check with a dial indicator. But if an alternator has noticeable side play, the bearings are too loose. Are are the bearings smooth ? If you spin it fast will it free wheel a couple of turns ? If it stops immediately, the bearings are likely too tight. If the bearings feel good, it should be ok to let it run. This should be a routine check to be done of all belt driven accessories from time to time. It could avoid a catastrophic bearing failure.



Another thing to beware of is if your engine has a belt tensioner, or if tension needs to be manually set from time to time. If a tensioner is old, and is has gone through several belt changes, it is due for replacement. I had a Cummins engine belt tensioner develop side play. It caused a belt edge to run over the edge of a pulley. This put side strain on the water pump bearing, destroying the pump, and causing coolant loss. After fitting a new belt, tensioner, and water pump, I also replaced the alternator as a precaution.


Electrically, if producing any voltage, there could be a small current flowing through the system in the normal direction. Such an under voltage is not good. However, if there is an internal short circuit or partial short circuit, for instance a diode conducting in reverse or a shorted voltage regulator, the alternator could discharge the battery, as current could back feed from the battery. Back fed current could do additional damage, as it will produce some heat. It would be interesting to measure for voltage with the load disconnected from the alternator to see if it puts out any voltage at all. But this would only be part of the story. It would need to be monitored with an oscilloscope to check for AC component. Of course not many cruisers carry an oscilloscope. Probably would be safest to disconnect the wire if you choose to let it rotate with the engine.


If you would like to learn more about alternators and charge systems, there are some good posts at https://www.cruisersforum.com/forums...ml#post3532722

[Cheechako]

If both alternators go to the same batterys/ bank, one may not be charging because it senses the voltage from the other.
I dont know how yours is wired.