Alternator hot at 180-200 degrees?!!?

[Saltwaterstinger]

So I replaced my alternator in my Mercruiser 5.7 Alpha1 Outdrive circa 1997-2000 because the batterys did not seem to charge well and there was a red dust covering and the pully wheel and fan wheel? were wearing out and not staying in sync. I noticed when I am charging Battery 2 (bigger of the 2) the alternator gets super hot and smells like new sneakers/ burning so I re checked all the wiring I did and started up again running on Battery 1. Battery 1 was showing 13.5 volts and the Alt was showing 13.5 from the orange wire and the red/purple wire. Battery 1 was not getting hot (temp went down to 140 degrees with a laser thermometer) which I still think is hot. Running on battery 2 I still got 13.5 from the orange and the red/purple wire but it rises up to over 200 degrees. I switched back to Bat 1 and it goes down in temp again. I have run the engine with the switch on bat 1+2 and I dont have any device telling where the power to go (i forget what its called). Im confused because this didnt seem to occur on the old alternator but maybe by putting in a second battery and running both at the same time effed something up and the new alternator is making it more obvious? What do you guys suggest I do?

here is the alt i got
http://www.motorcityreman.com/1194701md.html

I should also note that Battery 2 was low (10v) and I had to use both to start the engine. and I just read a thread from awhile back by the late Don S saying that an alt will get hot while charging a low battery... So maybe Im good and just let it get hot while charging the batterys to full? When I left the interior light on last night while on battery 1 and started the engine again on battrey 1, the alternator was hot again.

 

[achris]

Re: Alternator hot at 180-200 degrees?!!?

Yes, an alternator will get very hot when you put a high demand on it. Best charge the batteries on an external charger then put them back in the boat. That will reduce the load on the alternator and it will run cooler....

Chris.....

 

[alldodge]

Re: Alternator hot at 180-200 degrees?!!?

A reading of 13.5 volts during acharge is good, the Alt heat will increase the more demand placed on the Alt. A reading of more then 200 degrees is a bit high. Disconnect Bat 2, check water level, and distilled water if not over top of plates and put a battery charger on it over night. Next day turn charger off measure voltage, let sit for an hour or so and measure voltage again; voltage should read between 12.5 and 12.7 volts not connected to anything. If voltage reading is acceptable have it load tested. If all checks out I would like to see a picture of your setup.

The preferred method for testing the battery’s state of charge is to check the specific gravity reading of each cell. You can purchase a hydrometer at an auto parts store for about $10. The electrolyte is a solution of acid and water, so you need to wear safety glasses and gloves and avoid any contact with your skin. Remove the vent caps and check the electrolyte levels. There has to be enough in the cells for the hydrometer to pick up a sample. If you have to add any water, you’ll have to charge the battery and let it sit for 12 hours before testing. Fill and drain the hydrometer at least twice in each cell before taking a sample. Take the reading and record it, and then drain it back into the cell. Test all of the cells and replace the vent caps. Specific gravity readings for a charged battery should read between 1.235 and 1.277. Specific gravity readings below 1.235 indicate the battery state of charge is less than 80 percent and the battery needs to be charged. If there is a .050 or more difference in the specific gravity reading between the highest and lowest cell, you have a weak or dead cell in the battery.

Note: If your hydrometer does not compensate for temperature you must correct the readings to 80 degrees F. Add .004 for every 10 degrees above 80 degrees F and subtract .004 for every 10 degrees below 80 degrees F.

 

[achris]

Re: Alternator hot at 180-200 degrees?!!?

Hey alldodge, how do you check the specific gravity of the cells in a sealed battery (as most are these days)?

Chris....

 

[Volphin]

Re: Alternator hot at 180-200 degrees?!!?

Now, now, Chris... you know some are just sealed off from the public for their own good. LOL

 

[Fun Times]

Re: Alternator hot at 180-200 degrees?!!?

now, now, chris... You know some are just sealed off from the public for their own good. Lol

Must be an EPA thing.

 

[alldodge]

Re: Alternator hot at 180-200 degrees?!!?

Hey alldodge, how do you check the specific gravity of the cells in a sealed battery (as most are these days)?

Chris....

Golly gee wiz and all that kinda stuff,...
The fella didn't say he was using AGM or Gell so I kinda figured he might have a flat tip screw driver

:grouphug:

 

[Fun Times]

Re: Alternator hot at 180-200 degrees?!!?

Battery 1 was not getting hot (temp went down to 140 degrees with a laser thermometer) which I still think is hot.

While 140 would be an acceptable temp especially since you're relying solely on charging what sounds like may be older batteries? with the alternator. Ideally with new batteries, i'm used to seeing more of an 120-130 range.

Running on battery 2 I still got 13.5 from the orange and the red/purple wire but it rises up to over 200 degrees.

Like mentioned above, a high demand would bring the temp up. I just recently replaced an alternator that would get to 325 + degrees before the engine would get to normal temp of 163. And as luck would have it, he ordered an aftermarket alternator that luckily lasted the whole day of him using the boat before internally breaking down as he was heading into port. So now he's out money on the aftermarket alternator as he said it's not worth his time to fight with the company about it, So he now has an OEM Mercruiser alternator and the temp is running around 125 degrees days later.

What do you guys suggest I do?

If charging don't help, It may be time for new batteries.

I dont have any device telling where the power to go (i forget what its called).

Are you thinking of an battery isolator?

 

[Bt Doctur]

Re: Alternator hot at 180-200 degrees?!!?

Heres an easier way, remove the batteries and have them fully charged. Let the sit for about 4 days . Reinstall one of them and start the engine. Remove that battery and install the second one.
Most likely you will find #2 dead.If you cant keep a charge for 4 days ,the batteries are junk and need replacing.

 

[fishrdan]

Re: Alternator hot at 180-200 degrees?!!?

I should also note that Battery 2 was low (10v)

That battery either has a dead cell, or it's severely depleted. Both conditions would cause the alt to run hot.

I have a feeling a new battery is in your future........

 

[Bondo]

Re: Alternator hot at 180-200 degrees?!!?

That battery either has a dead cell, or it's severely depleted. Both conditions would cause the alt to run hot.

I have a feeling a new battery is in your future........

Ayuh,.... A Load Tester will tell ya in a few seconds,...

 

[FreeBeeTony]

Re: Alternator hot at 180-200 degrees?!!?

+1 on a bad battery........

 

[Saltwaterstinger]

Re: Alternator hot at 180-200 degrees?!!?

Are you thinking of an battery isolator?

Yes! :facepalm:

 

[Saltwaterstinger]

Re: Alternator hot at 180-200 degrees?!!?

Thanks guys great advice! I will check the levels tonight and throw them on a charger. took her out last night and was getting 14-14.4v from bat #2 when it was being charged by the alt and about 12.3 when bat #1 was being charged by the alt....I think we found the suspect:high5: