Replacing very old alternator

[model 10]

An internal regulated alternator on a boat can not handle the heat. You will toast a 100 amp single wire Delco in no time on a cruising boat with only 3 or 4 batts.

[lateral]

Originally Posted by Ecos

An internal regulated alternator on a boat can not handle the heat. You will toast a 100 amp single wire Delco in no time on a cruising boat with only 3 or 4 batts.

Not true for all internal regulators, the Auto ones downrate via thermistor so they don't heat up. But then the point of a high output alternator is lost.
I will concede that some Delco clone ones WILL heat up, presumably to melt winding insulation or diode damage level.
I have tried a Delco clone (120A)and it heated badly in a few minutes .
Switched to a cheap as chips Bosch & external regulator- Doesn't heat at all delivering
whatever current battery (and belt) will allow.
The bosch Does have externally ducted air thru a factory cowl.
Cost, $50. Probably doesn't need the external reg.

[john61ct]

Yes integral cooling design is key, many large-frame type are designed to output 70-80% the nominal (max) rating all day long.

Facilitating active ventilation helps.

Temp sensors are critical if pushing past 50%, and reducing **amps** output rather than voltage.

[BigAl.NZ]

Originally Posted by Ecos

An internal regulated alternator on a boat can not handle the heat. You will toast a 100 amp single wire Delco in no time on a cruising boat with only 3 or 4 batts.

Its only 1 batt. (starter)

[lateral]

Doubt whether a start battery would get discharged enough to draw much current from the alternator.
Having a 100A capable alt would be a good backup for the Balmar though, suitably regulated & cooled. (And switchable)