Alternator Overheating

[Pierre]

G’day

Out cruising today and smelt a weird smell on my Cummins 6BTA 5.9, had closer look and it was coming from the alternator. Took a temp reading and it was 109c the port was 87c……….

Any ideas or am I in for a new alternator

Thanks

Topic

[Rob Schepis]

Pierre,

DVM = digital voltage meters. Here’s the article I was referencing. Looks like you have a nice setup. Just need to be 100% aware as to how it works, how’s it’s wired in and what it can (and cannot tell you).
https://www.sbmar.com/articles/installing-digital-volt-meters-dvm-boat/

How about some more pics and info on the boat …. it looks like a beauty.

[Pierre]

Very interesting, as you say electrical is a different fame on a boat?

[Joe Monaco]

Electrical issues can be misleading and not obvious. Had a recent issue with my generator that had nothing to do with the generator. My starting batteries are for starting both the generator and the mains. After starting the generator I would then start the mains. All seemed normal during starts. Going down in the cabin I noticed the generator had shut down. Why? Turns out my engine intake heaters “toasters” for warm up pull so many amps that the fuel pump on the generator was losing power causing the generator to shut off. The problem was the starting battery’s going bad and were not holding during the large draw. Had enough power to start all the motors right up so very hard to know they where bad. So having weak/bad starting batteries were the cause of my generator shutting off. Weird stuff that electricity…

[Pierre]

Hey Rob

These are my displays

[Pierre]

Hey Rob

Good to hear from you, dropped in at my marina sparky and he popped down to have a gander, told me the batteries ran to low, we had some mad storms in Sydney and we lost power on multiple occasions and after 3 years of work, he reckons that pushed them over edge. The sulphur smell was coming through this morning.

Not sure what you mean by DVMs, but we been out for 8 hours now and we holding well, currently drawing 7 amps, sitting on 12.9v

Cheers Pierre

[Rob Schepis]

Good it’s resolved and thanks for posting the end result.

How did you learn this?

Are you measuring and displaying battery terminal voltages such as the DVMs discussed on this forum?

[Pierre]

Hey All

Okay problem solved, found I had a dead cell in one off the deep cycle batteries, this caused th ALT loading up and running hot, ran off this morning and bought 2 x 290 AGM batteries. Fitted them and we back to normal, ALT on the starboard engine now 65 degrees C.

So all revolved around the batteries.

Cheers P

[Philip]

Get the alternator off and take it to an alternator shop for testing. They will be able to tell you if it’s an internal alternator issue. Hopefully so and they can rebuild the alternator problem solved.

If the alternator tests ok then you have some other issue going on external to the alternator in the wiring etc….

Start with the alternator

[Pierre]

Morning Rob and All

Thanks for the reply, did a few checks today, ran the batteries up 100%, checked voltage 12.5v, started starboard engine and kicked it up to 2000rpm, put everything on. Did a voltage reading and it came in at 14.7v, so it seems to charging the batteries okay.

But within a minute you could smell that burning smell and the alternator got up to 98 degrees C.

Took belt cover off and no slipping, belt in could condition. So not sure what is going on, port alternator is good.

[Rob Schepis]

Good looking boat, how about some info and pics of it.
Could you have a DC issue that is taxing the alternator?
Could the smell be battery sulfur?
Is the alternator hot with the engine not running?

[Author]

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