Alternator burnt up with 100 engine hours?!?

[Sam Woodbridge]

Hello Everyone, I just read S/V Jedi’s post about alternators and got me thinking why not ask you guys about my problem.

I’ve owned this boat for a week and half. It’s a 2018 Beneteau sailboat with a Yanmar 3YM30AE. It has a Balmar alternator. I pulled the alternator out yesterday and dropped it off at a shop for testing on Monday. The person who took the alternator did confirm it had burnt looking bindings and had a burnt smell to it.

My question is how could that have happened with only 100 engine hours? What a complicated system too on this boat with, a microwave, inverter, bow thruster, windlass, water heater, and water pump etc.

I’ve noticed when using the windlass the battery charging alarm always came on. I would then throttle up the motor hoping to get the alternator to kick out more juice, but it didn’t help. (Motor has to be running to operate the windlass)

I’ve also notice on a side note. Without shore power I’ve used the inverter - once the inverter is on the microwave light comes on. So, I thought let’s try it out. After running for 10 seconds it trips the breaker.

In short does anyone have input on what could cause a bad alternator so early. With the system I have with all this fancy stuff could there be a no brainer mistake somewhere that a new person like me wouldn’t be aware of?

Thank you - Sam

[goboatingnow]

The controller probably overdrove the alternator and cooked it. Most small case alternators especially when in the confines of a boat engine enclosure will seriously overheat of driven anywhere near their rated output

You need to be very careful when adding a smart alternator controller to a stock alternator. You must fit an alternator temperature probe.

[Sam Woodbridge]

Originally Posted by goboatingnow

The controller probably overdrove the alternator and cooked it. Most small case alternators especially when in the confines of a boat engine enclosure will seriously overheat of driven anywhere near their rated output

You need to be very careful when adding a smart alternator controller to a stock alternator. You must fit an alternator temperature probe.

Thank you for your input Gobiatingnow. I’ll check about the temperature probe and look into the controller.

Thanks again - Sam

[AndyEss]

What kind of house battery bank do you have? How old are the batteries? If flooded lead acid, did you check water levels?

The electrical system you describe doesn’t sound particularly “complicated”. For instance, most cruising boats have multiple water pumps. At least you didn’t mention an all electric kitchen with induction stove tops. For what it’s worth, my inverter can’t drive my small microwave either, so I only use it the rare times I have shore power.

[sailorboy1]

You have more than an alternator problem I feel. I bet currently you have a battery problem.

[Sam Woodbridge]

Thank you for the replies,

AndyEss, I have two and half year old AGM house batteries. And they are the Intimidator series. I believe the batteries are sealed, but I look them over today and see if I can check the level.

Sailorboy, yes I’m worried it’s more than a alternator too. I know the house batteries hold a charge. I was anchored out for two days and not running the engine. I ran the webasco diesel heater and used my lights morning and nights. Along with the water pumps and stuff. The batteries did ok they where at 12.0 volts when I left.

Thanks again for the replies. Sam

[Mickeyrouse]

Batteries at 12 volts are fairly discharged. Depending on type, I would want to see fully charged batteries at 13.2 to 13.8

[Sam Woodbridge]

Originally Posted by Mickeyrouse

Batteries at 12 volts are fairly discharged. Depending on type, I would want to see fully charged batteries at 13.2 to 13.8

Thanks Mickery for your thoughts. I agree batteries at 12 volts are low, but I expected that from two days of using them without anything charging them. Do you think after two days of using them they should have held a higher voltage?

Thanks again - Sam

[tml]

Our Balmar caught on fire with less than 20 hours use several years ago.
After no small amount of frustration and a couple more cooked alternators we learned
1) Balmar alternators will only run at their advertised capacity for a few minutes without melting down.
2) The solution is to derate the alternator to 75% ish advertised capacity. Even then it can over heat which can be managed with a temperature sensor on the alternator, When it overheats the controller will further reduce output until the temp comes down.

TML

[Sam Woodbridge]

Originally Posted by tml

Our Balmar caught on fire with less than 20 hours use several years ago.
After no small amount of frustration and a couple more cooked alternators we learned
1) Balmar alternators will only run at their advertised capacity for a few minutes without melting down.
2) The solution is to derate the alternator to 75% ish advertised capacity. Even then it can over heat which can be managed with a temperature sensor on the alternator, When it overheats the controller will further reduce output until the temp comes down.

TML

Wow TML, that seems like a horrible experience. I’m wondering if your boat was covered under warranty? This boat still is under warranty, but not over engine related issues.

Thank you for taking time to share your experience. I’ll definitely ask the shop who has the alternator about derating it.

[tml]

Originally Posted by Sam Woodbridge

Wow TML, that seems like a horrible experience. I’m wondering if your boat was covered under warranty? This boat still is under warranty, but not over engine related issues.

Thank you for taking time to share your experience. I’ll definitely ask the shop who has the alternator about derating it.

Sam
I assume your alternator is paired with a Balmar controller which may be installed in the engine compartment or near by. The controller can be programed to manage the output and the alternator temperature.
Balmar repaired the alternator but all other expenses were mine. The were less than candid about the cause.
TML

[Sam Woodbridge]

Originally Posted by tml

Sam
I assume your alternator is paired with a Balmar controller which may be installed in the engine compartment or near by. The controller can be programed to manage the output and the alternator temperature.
Balmar repaired the alternator but all other expenses were mine. The were less than candid about the cause.
TML

Yes TML it does have a control panel which is near by. I’ll definitely see what I can find on the internet about it and how it’s programmed!

Hmm, interesting they where less than candid about the cause. Although I’m happy for you they repaired your alternator.

Thank you TML

[sailorboy1]

Without knowing the battery capacity, the alternator capacity, and the alternator regulation type and settings it is impossible to really go beyond the comments already made

[jack630]

I would recommend going to marinehowto.com and read all the articles about batteries, alternators and regulators. It will make your head hurt but it's all there.

[Sam Woodbridge]

Originally Posted by jack630

I would recommend going to marinehowto.com and read all the articles about batteries, alternators and regulators. It will make your head hurt but it's all there.

Thank you Jack, I’ll take a look at marinehowto.com