The Sterling units are well designed, quality products. We are using the Pro-Reg D with a high output Delco style alternator (way cheaper than a Balmar). The Pro-Reg D requires modifying the internal regulator wiring
inside the alternator housing. It bypasses the internal regulator and controls the alternator field voltage to achieve a longer and higher output 4 stage charging current
profile. It includes microprocessor control, is programmable for different battery types, and also monitors alternator and battery temperature. Cruising and anchored out for several days, recharging a large 440 Amp Hour battery bank (at ~ 20% discharge) takes no more than an hour per day of engine time.
The Sterling Alternator to Battery Charger works by creating an artificial voltage drop in the field current
, "tricking" the alternator into a higher output profile. It does not require any internal modification of the alternator. I have no personal experience with this unit but can see in the Sterling info that it has a large heat sink and requires significant cooling
, which no doubt means it is not as efficient as the smart regulator units.
Balmar offers a 4 stage smart regulator system matched to their excellent line of premium priced alternators.
My only caution with the Sterling systems, particularly the Pro-Reg D, is that they do require knowledgeable installation. The manuals
provided require some interpretation by an installer with a good foundation in DC charging and wiring
. Sterling is a small company in England
-- getting an answer to a tech question can be a challenge.