Smoked alternator

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fryedaze

fryedaze

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Joined
Sep 4, 2011
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1,722
Location
USA
Vessel Name
Fryedaze
Vessel Make
MC 42 (Overseas Co) Monk 42
I was crossing the Okeechobee a few days ago on a friends Kadey Krogen. The boat has a 160 amp Balmar alternator and a Balmar MC 612 regulator. They have worked great for over 5 years. During the trip we had smoke coming from the alternator and it read over 300F moments after we shut it down. I noticed the previous day that the alternator wasn't recovering the batteries but may have been putting something out.
Is there anyway to ensure the regulator is OK. I would hate to put a new alternator on and have the regulator burnt it up?
 
Well, there are several possible issues at work here.


1. Did some large, unexpected load due to a shorted wire or whatever cause the alternator to put out a lot of amps long term which fried it?
2. Did the regulator go into full field mode which let the alternator put out a lot of amps which fried it. Not likely if the batteries were not charging well.
3. Most likely the internal windings in the alternator shorted resulting in rapid overheating. This should not affect the regulator.


I guess I would put a new alternator in but monitor the charging current output to make sure that some short isn't loading it up.


David
 
Take both the reg and alternator to an alternator shop, usually if alt smokes it is the stator, which is replaceable. Diodes can burn up but rarely smoke.

Reg if a problem can cause alt to over work, and that's what burns up stator. So it needs to be checked. If a pain to get it out, just fix alt and install it, then test it with engine running and reg in normal config, and monitor volts and alt stator temp.
 
Does the alternator have a high temperature cutout? If not and you go with a new one something to consider. 5 years is not very long so a good systems check as Ski suggests is definitely in order.
 
Many of the Balmar products are std frame alts with a power package installed.

They will put out high amps but are limited in long periods of operation by their cooling.

The HOT rating is seldom high so pushing the output with a better marine V reg requires caution.

A new built truck 160A large frame alt will have a far better HOT rating ,and is probably half the cost, but can be a big PIA to install.

If you spend time cruising and on the hook, the hassle is worth it.
 
djmarchand said:
Well, there are several possible issues at work here.


1. Did some large, unexpected load due to a shorted wire or whatever cause the alternator to put out a lot of amps long term which fried it?
2. Did the regulator go into full field mode which let the alternator put out a lot of amps which fried it. Not likely if the batteries were not charging well.
3. Most likely the internal windings in the alternator shorted resulting in rapid overheating. This should not affect the regulator.


I guess I would put a new alternator in but monitor the charging current output to make sure that some short isn't loading it up.


David
Click to expand...


The regulator indicated a setpoint of 13.8 and the output was 13.4. I assume it was in absorbtion mode.
The batteries are good. The genset brought them back up normally and they held.
 
sunchaser said:
Does the alternator have a high temperature cutout? If not and you go with a new one something to consider. 5 years is not very long so a good systems check as Ski suggests is definitely in order.
Click to expand...

No temp protection hooked up to battery or the alternator.
 
Is it possible that a diode or two failed on day one and then on day two the other diodes failed and smoked when the batteries were being charged after the engine start. The alternator smoked about 30-45 minutes after the morning engine start. As I indicated before it looked to me like on the previous day the alternator was at reduce output.
 
too much load for too long a time. I would recheck the batteries looking for a bad cell. using an hydrometer.
 
Diodes can fail then reg tries to boost output, then stator cooks. So definitely could have started with a diode failure. Balmar buys their alts from other vendors, so diodes and stator can be sourced from OEM vendor. Alt shops can look at it and ID it immediately. No need to go to Balmar.
 
A good alternator shop is worth it's weight in gold. They can repair and test your alternator and starter for a fraction of replacement cost and when done they're every bit as good as new.

Ken
 
"So definitely could have started with a diode failure"

This can sometimes be EZ to notice.

If at idle any lights seem to "bounce" in brightness , you may have lost one, or more.
 
Thanks for the input TF folks. I will follow up with the rest of the story after the trip to the alternator shop.
 
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