Balmar 618, fuse blowing

[elliot_russo]

The Balmar 618 is regularly blowing its 15A fuse. Last time appeared to happen when going to higher revs after a period at idle. Started happening after doubling lifepo4 bank size. Alternator is an older Loadhandler 130A large case. It is putting out at least 115A. I'm guessing bursts of high field amps is triggering it. FWIW Im not seeing more amps being produced than before I increased the bank. Mainsail suggested on another thread 20A fuse would be ok. Wondered also whether upping cable size would reduce v drop and lower amps pulled. Otherwise going to put resettable fuse in place of blade.
Thanks in advance

[GordMay]

Balmar “MC-618" Manual
➥ https://balmar.net/wp-content/upload.../06/MC-618.pdf

If the manual doesn’t help, try contacting Balmar technical support staff at:
Tel: +1(360) 435-6100,
E-mail: balmar@balmar.net

BTW: Mainesail is a very reliable source.

[nuku34]

To the OP: I would first look at all the wiring from reg; make sure it is correct wire gauge for the expected amp draw, and that all terminals are corrosion free and wires properly crimped to the terminals.
The reg is basically just supplying current to the positive brush of the alternator field current winding via the reg red wire that connects to a +V source (B+ output stud of the alt or directly from the battery) and the blue wire that goes to the alt field. The field circuit is completed by the negative brush which will generally be grounded within the alternator to the alternator frame and through the engine to the negative post of your battery bank.
The problem seems to be that the alt field is drawing more than 15 amps. A large alternator can require more than 15 amps in the field circuit when the voltage in the circuit approaches full battery voltage. So yes, I'd try a 20A fuse in addition to cleaning up all the wiring.

[elliot_russo]

Originally Posted by GordMay

Balmar “MC-618" Manual
➥ https://balmar.net/wp-content/upload.../06/MC-618.pdf

If the manual doesn’t help, try contacting Balmar technical support staff at:
Tel: +1(360) 435-6100,
E-mail: balmar@balmar.net

BTW: Mainesail is a very reliable source.

Thanks both of those done. No real joy.

[elliot_russo]

Thanks, all wiring is new, and as supplied as harness kit, all connectors good. I'll upgrade fuse.

[witzgall]

Chris from Balmar here. The typical cause of the 15A power fuse blowing is voltage spikes from load dumps. Not many alternators draw more than 15A, but that is possible.

The MC-618 is rated for 15 amps of field current. If you exceed that, and replace the fuse with a higher rated fuse, then a resettable fuse within the product will likely trip, and then reset when the current (heat) drops down. If the current is till over the limit, it will happen again.

Bad connections will likely result in lower output and heated connections, not ba blown fuse, unless it is the fuse holder itself that is damaged, as that would could cause localized heat in the fuse holder.

Chris

[elliot_russo]

Originally Posted by witzgall

Chris from Balmar here. The typical cause of the 15A power fuse blowing is voltage spikes from load dumps. Not many alternators draw more than 15A, but that is possible.

The MC-618 is rated for 15 amps of field current. If you exceed that, and replace the fuse with a higher rated fuse, then a resettable fuse within the product will likely trip, and then reset when the current (heat) drops down. If the current is till over the limit, it will happen again.

Bad connections will likely result in lower output and heated connections, not ba blown fuse, unless it is the fuse holder itself that is damaged, as that would could cause localized heat in the fuse holder.

Chris

Thanks Chris. So is a 20Amp blade fuse OK, or could I replace with a 15A resettable. Are you saying there is a resetting fuse in the device as a final line of defense. What sort of delay profile is required.

What sort of load dumps? Last time, it was fine for ramp up, then we went to idle for passing whale, then up to cruising rpm, and it blew. If I lower from 100% I assume that will help for now? Could 100A windlass do it?

[smac999]

I would pull the alt off and have a shop check it. It should not be pulling 15a field current.

I’ve installed ~100 balmar regs and never seen one blow a fuse.