There are plenty of well priced alternators out there without the 'recreational boater' $ surcharge that put out serious amps continuously and meant for thousands of hours untouched.
Large frame alternators of the school
are a good bet. I ran my last boat
with two Prestolite (one main engine, one Kubota generator
unit) 24v 140A and they would do it all day for many years. As well as battery charging
, they supplied all 240v power through inverter
for air conditioning
in tropics so could have serious load for 24 hrs a day. 12 years and couldn't kill them even with a dead short due to a burst seawater coolant
hose that burnt the belts off both. Only drawback was with Kubota unit that pulled that much power putting out big amps at an idle that it would stall a cold engine. Easily sorted with a delay relay in excitation between regulator and main unit. Adjustable internal regulator but easily fitted with external regulator that so many people seem to like to complicate their life with.
has Cummins QSB 5.9 engines with el cheapo 100 A, 60 A after no time on charge and no room for big frame alternators. Fitted Delco (US manufacture, not Chinese made or knock off). Found a bracket to suit different mount and fitted 28SI 160 A, well proven industrially for thousands of hours. Puts out 160-120 amps for hours to bring batteries
up, doesn't get hot and no issues after 400 hours.
But it is all kept simple, original Balmar dual alternator set up in bin, one engine house batteries, other anchor winch
, thrusters own battery and charger
, batteries on old boat FLA, new boat AGM
IMHO most alternator damage is done at idle when left to idle to 'warm up' with batteries down and alternator flat chat at max and very low rpm
. Similarly, idling when pulling anchor
. I always warm engines when batteries are down at a high idle and similar when pulling anchor. Not going to hurt the engines and gives the alternators a chance.
I have to agree with one of the earlier comments that you get what you pay for and weight and country of manufacture are a good indication of what you are getting. We all dream of the super bargain but robust quality things have a price
With lots of things, I always look to industrial applications which are similar and there are usually well proven solutions with very competitive pricing in a big market rather than the relatively small recreational marine