For those who have a Yanmar with a Hitachi and don't want to spend $1000.00 plus on an alternator upgrade I recently developed this 80A medium duty Yanmar/Hitachi frame alternator that is already set up for external regulation. The CMI-80-ER is also an excellent value at $349.00
For boat owners with Motroloa/Prestolite/Leece-neville 8MR case alternators I have an article HERE that shows you how to convert your own alternator to external regulation.
For external regulators I highly recommended the Balmar MC-614H or the ARS-5H. Oh and don't forget about proper voltage sensing when wiring your new system. Alternators & Voltage Sensing Why is it Important?
Summary:
In short, smart regulators and performance alternators most definitely do have a place on cruising boats and they are tremendous tools. However, their use should ideally be well justified for the expense laid out.
The installation of a smart regulator should be considered in the total system design. Their use is very often justifiable, but occasionally it is not, especially for a weekend use coastal cruiser. It can just a big expense with marginal gains for the weekend / over-nighter who is charging at a dock all week.
A small bank of inexpensive flooded batteries, for a day boater or weekend cruiser, does not absolutely require a $1000.00 + charging system when a simple dumb regulator, with the proper voltage setting, can work suitably well. A good battery monitor, properly programmed, or another way to monitor SOC performance, such as the Balmar Smart Gauge is often a better place to start than a $1000.00 plus alternator upgrade.
If you want or need expensive high acceptance batteries, or a large bank, I would strongly suggest you buy an external regulator and a high output alternator. If your batteries are located in a hot engine compartment then you really should have an external regulator with battery temp compensation. Heat kills batteries and the voltage needs to be compensated when batteries are hot.
If you are a weekend boater, with flooded cells, at a dock all week, and your alternator is already putting out 14.4 volts or so (not a thermistor alternator), stick with it and you'll probably do just fine unless your bank is huge.
Good luck & happy boating!
