Yanmar alternator

[CLP]

I have a 6 year old Yanmar 2GM20F with a 55 amp alternator. I am thinking about adding a split charger into the system so I can charge 2 battery banks. To do this apparently I need to know if the alternator is "machine sensed" or "battery sensed". Can anyone help please?

 

[bonny]

It's probably machine sensed, my 1998 1GM10 was.

If you're going to use split charge diodes then you need to battery sense. But what I did was to use a split charge relay (12V relay capable of switching over 60A) with it's coil connected between batt-ve (ground) and the alternator side of the no charge warning light. The relay then operates ONLY when the alternator is generating and connects the 2 batteries together only then. This ensures the engine starts from it's (hopefully) fully charged staring battery, the flat leisure battery wont connect untill the engine has started. Don't power the relay from the engine power switch because this operates the relay when engine is switched on (not necessarily running).

 

[snowleopard]

it is definitely machine-sensed.

to use a splitting diode it is essential to use an external regulator as otherwise, with a 3/4 volt drop through the diode you'll get virtually no charge into the battery.

 

[pvb]

Not necessarily essential...

You can easily get an alternator modified to add a battery sensing wire, this avoids the expense of a smart regulator, although of course it won't charge as efficiently as it would with a smart regulator.

 

[pvb]

Easiest solution...

Your easiest solution would be to fit a VSR (voltage sensitive relay) rather than a diode splitter. No voltage drop. No alternator mods needed. Similar price. See here for details from one supplier.

 

[mrcruisine]

Hi, John Payne here. Its a negative sensed unit, had same on my own Yanmar and also fitted lots of Advercs and TWC to same. They are hellish to modify so opt for smart electronic battery switches as diodes are not an option with loss of 0.7 volts and I cover this in my books also. With smart switches the sensing issue doesnt arise. web page

 

[halcyon]

If you use a relay unit, it makes no differance to the type of alternator regulator.


Brian