Hot alternator

[magster65]

I anchored for the night and left some accesories running like the fridge (1 of them), some lights and music. In the morning both engines started no problem.
After I started to head back home (just putting) I noticed a smell so I popped the engine hatch to see if it was coming from my boat... and it was. It had a 'hot' smell to it. I shut her down and took a look around the engines... all I could find was the port alternator was really hot... too hot to hold your hand on it. :smt009
The voltage was 14.4 +/- on the starboard and about 13 on the port when running. The smell went away and by the time I got back home they were both at 14.5 running.
I didn't lift the hatch again 'cuz we were all tired and wanted to get home.
I guess I'm going to load test the batteries and throw a volt meter on the alternator... anyone think of anything else I should check?

 

[chumbley]

Too hot to hold your hand on is not abnormal for an alternator putting out max current for a period of time... Still worth checking everything over though.

 

[Loneranger]

http://www.raytek.com/Raytek/en-r0/...eries/MiniTemp-AutomotiveHandheld/Default.htm

An infrared thermometer is one of the best tools I have put on the boat. I have the MT6 which from Amazon is only $56. I think I found it on sale for less than $50 so it may be worth waiting and looking for a sale. Having the thermometer has ended the "felt hot" problem. It is also useful to get the boat up to operating temperature and then take temps of various parts of the engine when everything is working normally so you have a baseline to compare.

John

 

[magster65]

I went and tested.
All 3 batteries are the same at a little under 13 volts (12.6ish). I load tested them @ 100a for 10 seconds... no voltage drop to speak of. I couldn't smell anything in the engine compartment of concern. I started it up; starboard engine smart craft said 14.3 volts / port engine 13.8 volts port at first then it went to 14.0 and stayed there. The engines idle at the exact same rpm. After 6 or 7 minutes the alternaters weren't hot and were the same temperature... Before it was the port alternater that felt hot. I sniffed it closely... no smell and all the wires were still pliable and looked fine.
To me there's nothing wrong with those numbers and a close visual and sniff test checks out but something happened... I guess I'll just run it and keep an eye on things for now.
Any thoughts anyone?

btw; original batteries I think...

 

[chumbley]

John those numbers look good to me. Have you ever validated the smartcraft voltages with a real voltmeter? If not, that would be one more step.

 

[magster65]

Yes. I borrowed a good quality "Fluke" multimeter from work and confirmed the voltages. The smartcraft guages are right on the money.
It all looks good yes but I kind of wish I found a problem... know what I mean? I had a really good look around but I'm going back again today to look some more...

 

[magster65]

Update;
I've found that after being at anchor overnight (with 'stuff' on), in the morning I have lots of juice to start and go but the port side indicates a lower voltage for a couple hours. I see about 12.5 volts running after start up and 2 or 3 hours later it's at 14.3 like the starboard. Is this just a lower voltage because the battery is charging?

 

[midway]

Yes, the simple way to explain it is, it takes volts to push amps, when you first start up the amperage for charging is high and the voltage is low, as the batteries charge the amperage drops and the voltage climbs. Sounds like things are working as they should. I still wonder if there is not something wrong with the batteries that it takes so long to recharge, may be perfectly normal but if it has just started I would check some more. It could just be that the alternator has to supply enough amperage to run the accessories and still recharge the batteries, could be one of the things you have running that is drawing excess power.

 

[magster65]

These are 70 amp alternaters I think. I pulled it out and took it in for a bench test and it works perfectly.
As for the recharging time... it does seem a bit long but I could be wrong. While it's trying to recharge the batteries I have... what... 2 fridges, a gps, and a stereo (which has an amp) running so which do add up I suppose. All that stuff doesn't have to be on...
I'll just keep an eye on it for now.