Glenn, I seem to have missed the reason you want to use a different
regulator on the Yanmar alternator.

Are you having problems with the stock regulator/battery combination?

If you use the staring battery only for starting, it should last a very
long time with the stock regulator. Except for being able to perhaps
control the float voltage, a multi-stage regulator is not likely to add
much life or reliability to your starting battery. The multi-stage
regulator's real benefit is that it can restore a lot of energy more
quickly than the stock regulator. That is never a requirement for a
starting battery in normal use since the starting function draws very
little energy from the battery. It ought to stay at very close to full
charge under normal running conditions. Unfortunately, the same cannot
usually be said for house batteries that are often discharged to 50% or
less of capacity.

Hundreds of millions of starting batteries live very happily with stock
regulators in cars, trucks, buses, boats, etc.

Chuck


Glenn Ashmore wrote:
Working on installing the regulator and battery switches for Rutu. The
complicating factor is that I have a BIG Leece-Neville charging the house
bank and the stock Yanmar alternator charging the starter battery. There
are two battery switches. A straight on/off at the house bank and a
1/2/Both at the engine.

The 1/2/Both switch has a field disconnect feature to prevent damage if it
is operated with the alternator running but in the normal arrangement
switching the hot side it only works for one alternator. The Leece-Neville
is externally regulated but the stock alternator in internally regulated.
I am thinking that by switching the field ground rather than the hot side I
could get it to work for both. The LN is not a problem because I know how
it is wired but I can't figure out how the stock Yanmar field is grounded.
The Yanmar installation manual doesn't mention the alternator wiring.

Is there a way to bring the field ground on a stock Yanmar alternator out to
a switch?