Alternator charging without field wire

[sv_isara]

Hello there,
I have a relatively new (about 6 hours of use) Stirling regulator, and it seemed to be working fine. It would have the overtemp come on and reduce alternator temperature.

However, yesterday while watching the blue angels during fleet week, the light went on for overtemp, and I believe the field voltage was probably reduced momentarily because I heard the engine rpms increase for for a half second - however then the alternator went back to full charge pushing 140 amps, and overheating. The overheat light was still on on the regulator.

I then disconnected the field wire and...no change! The alternator was STILL pegged pushing out 140 amps! Not a good thing when you have a fresh lithium install

So long story short - field voltage with engine off (but instruments on) is 0. With the engine on it's full voltage - 13.5 or so.

Is this a fried alternator? Anything I can fix or check? Not familiar with this failure mode when the field current isn't being supplied by the regulator yet still giving full charge.

Previously, I have disconnected a different regulator from the field wire and it would stop the alternator from charging.
Cheers

[smac999]

alternators receive field voltage. they don't produce it. the external reg produces the voltage and sends it to the alt. with the field wire disconnected the alt will shut off. and would have 0v on the feild connection at alt. the wire from reg would have voltage.

if the alt is running with no field wire then something is wrong with it. was it converted to external regulation? or did you atempt to hook up an external reg to a standard alt without moding it?

[sv_isara]

Originally Posted by smac999

alternators receive field voltage. they don't produce it. the external reg produces the voltage and sends it to the alt. with the field wire disconnected the alt will shut off. and would have 0v on the feild connection at alt. the wire from reg would have voltage.

if the alt is running with no field wire then something is wrong with it. was it converted to external regulation? or did you atempt to hook up an external reg to a positivestandard alt without moding it?

it's an electromaax cruiser 140a, not modified. manual says it's a positive field excitation. voltage was
measured at field terminal on alternator, with regulator field wire disconnected.

[smac999]

Originally Posted by sv_isara

it's an electromaax cruiser 140a, not modified. manual says it's a positive field excitation. voltage was
measured at field terminal on alternator, with regulator field wire disconnected.

Sounds like you have a problem with the alt.

Does that alt have an internal reg as well? Some of the balmars can do both. If so you need to make sure the internal reg is not getting power when using the external.

[GordMay]

ElectroMaax Cruiser Marine Alternator:

“... We recommend our multi-stage E-MAAX Smart, External voltage regulator to control these alternators, with the internal regulator kept disconnected as a back-up...
... To protect and extend the life of your batteries, this alternator should always be used in conjunction with a smart, multi-stage regulator like our E-MAAX Smart, External charge controller. Due to its compact size to massive output, the 140 Amp Cruiser is a perfect solution in environments where a separate generator or large-case alternator are not possible. Includes internal two-stage regulator, and can also be used with other external voltage regulators...”

➥ https://electromaax.com/products/cruiser/

Current Manual ➥ https://electromaax.com/pdfs/cruiser...n-manual_1.pdf

Pre 2021 Manual ➥ https://electromaax.com/pdfs/cruiser...al-pre2021.pdf

[Oceanride007]

Could the field wiring also be taking its power from ignition switch, if that was so the alternator fail light would be active on the engine panel. If its not active the field wiring is getting power from somewhere.

[sv_isara]

Originally Posted by GordMay

ElectroMaax Cruiser Marine Alternator:

➥ https://electromaax.com/products/cruiser/

Current Manual ➥ https://electromaax.com/pdfs/cruiser...n-manual_1.pdf

Pre 2021 Manual ➥ https://electromaax.com/pdfs/cruiser...al-pre2021.pdf

I read everything on it but it's still not clear to me if there's an internal reg. I will call them and/or open it to find out.

[sv_isara]

Yep, internal reg. Disconnected one of the wires as per customer support and it's all good - except the stirling still lets it run hotter than I'd prefer.

[wholybee]

Originally Posted by sv_isara

Yep, internal reg. Disconnected one of the wires as per customer support and it's all good - except the stirling still lets it run hotter than I'd prefer.

Not familiar with the capabilities of the Sterling, I just looked up the specs and manual. It doesn't support LFP. It might be time to upgrade. What battery type do you have selected now?

[sv_isara]

Yeah I just upgraded to lfp. Trying to get a new alternator installed but I have to figure out how is regulated first.
I have the victron battery to battery charger but it won't disconnect using a float mode. Seriously considering a manual combiner switch for the engine and house banks