, We have an electrical engineer
in our group and he researches and recommends all of our electrical decisions. When our alternator gave up the ghost about 3 years ago, he recommended a Balmar Series 6 - 70 amp alternator as its replacement due to the Balmar's power production curve as it produces its full rated power at a very low RPM and would not require a modification to our alternator drive set up (single V belt). We ran that configuration for 3 years, using the alternator's internal voltage regulator, until just recently when the alternator's regulator gave up the ghost. Further research revealed that the integrated regulator is basically intended as a back up, get you home system using only a single stage
, bulk charging schedule. Balmar and Peter Kennedy of www.pkys.com
recommended the use of a Balmar ARS5 external regulator, which is a 3 stage
(bulk charge-float charge-maintainer charge) regulator, incorporating a battery temperature sensor and an alternator temperature sensor to better regulate the charging schedule. We have just installed the ARS5 with sensors and will see how it goes. We have 4 high dollar AGM batteries aboard (2 @ house / 1 @ start / 1 @ windlass) and an Air Breeze wind generator for a 24/7 topping current in the trade wind BVI's. Pardon my rambling on, but hope our experience helps. George
PS - If memory serves me correctly, we only need 1200 engine RPM to produce 2400 alternator RPM which delivers full rated current. The boat gets used 10 months per year, with a 2 month lay up. I just recently purchased for $300, a 1 year old Balmar 912 - 75 to 100 amp alternator with an ARS5 external voltage regulator from Cruiser's Forum Classifieds for use on my personal boat in NC.