Battery charging systems used with twin diesel engines.

[waterman46]

Originally Posted by rabbi

In my last boat I had a simple yet effective setup.
Both engines run on one starter engine.

Did you mean one starting battery, not one starting engine?
Yes I would think you only need one starting battery for the two engines.

I looked more carefully at the manual for the Balmar MC614, the latest model. And I have on my boat the older model, I believe it is MC612. Seems the new one has more intelligence in how it monitors battery state of charge. With the older model it seems that once it reached float mode it would stay there as long as power was applied to regulator, even if a large current demand say for reefer,etc, caused significant drop in battery voltage and subsequent battery partial discharge.

According to the manual, model MC614 once in float mode will look at field current required to maintain float voltage every so often. If it finds alternator is having to output significantly more current to maintain float voltage then it will increase voltage back to absorption mode for a while. Some of these details are programmable. If that is true it would probably solve the main issue I mentioned in my OP.

[n2climbing]

Take a look at Balmar's "Centerfielder." We installed one in March in our new Leopard 40 and have been happy with it so far. With the 125A Valeos that now come with the Yanmar 3YM30AE's we have a theortical maximum charging amperage of 250A (the Valeos need to be retrofitted for external regulation and smart regulators such as Balmar's MC-614 need to be added). We also disconnected the direct charging link from the alternator for the engine start batteries and added Balmar Digital Duocharge units which manage engine start battery charging via "spill over" from the house bank. Balmar's website has lots of useful information on these systems.

[rabbi]

Originally Posted by waterman46

Did you mean one starting battery, not one starting engine?
Yes I would think you only need one starting battery for the two engines.

Correct (just a brain fart on my side)

My point is:

You have a catamaran, so plenty of real estate for solar. If your plan is to cruise in the sun, make use of the sun. Solar is cheap these days.

Once you have enough solar panels this engine charge thing becomes so unimportant that you can easily live with the simplest solution you can find (its used very rarely anyway).


Today I would not go for the B2B charger anymore. A manual switch to bridge engine & house batteries would be good enough.
Or a simple 180A battery coupling relay between engine & house battery, triggered by D+ of just one engine. Total cost maybe 25 Euro