I have two alternators in my armory, a 110amp and a 300amp unit. I have just installed am ammeter to confirm the actual demand, since I am now running 2 x pumps and a high volume fan for the interchiller, and found the draw to be 72 amps. I have trawled the internet without certainty beyond the numerous speculated claims of what my aunty uses etc. I could jump straight to the 300amp unit, however keen to understand if there is a known demand rating for 14V alternators? My previous understanding was automotive alternators had a 5-10% duty rating at nameplate, by then the crank depletion of start up had been replenished, so the alternator demand dropped to the nominal headlight/heater/a/c/ etc load.
Specifically will my 110amp alternator withstand the demand of a 70amp draw over an extended period of time? Added to this worst case would be driving at night, country miles and perhaps low range into a camp at times, so this could jump to say 90 amps with my set-up. For clarity, its either the 110 or the 300 installed, not both. They are a cartridge change out, takes about an hour to do.