Yanmar Circuit diagram

[Dave_Rolfe]

Does anyone know of the whereabouts of a circuit diagram for a Yanmar 2GM20. I have seen the one in the workshop manual but find it none too clear.

I am particularly in need of detail of the charging part of the diagram i.e. where the cables come off the alternator and go to the starter. I am trying to wire up a Sterling alternator to battery charger and am bypassing the normal route of the charge (Via the starter cable) and wiring the Sterling unit direct to the alternator. This will enable me to continue to use the 1-2-both-off battery switch. If I use the starter cable to carry the charge it bypasses the Sterling unit. I need to identify which cable originally carried the charge to the starter so I can isolate it.

Despite help on this forum already (lots of it, thanks) I am still struggling.

 

[Dave_Rolfe]

I have just found another diagram in the Yanmar manual and it seems to make more sense now but if anyone knows of a different one please let me know, thanks.

 

[KenMcCulloch]

You will find a RED wire going from the alternator to the +ve terminal on the starter solenoid, shared with the heavy duty +ve wire from the starter battery isolator switch. That's the wire carrying the charging current from the alternator to the battery so you need to disconnect that and connect the new charging wire in its place.

 

[pvb]

KenMcCulloch has already given you the answer that you need to remove the wire connecting the alternator's BAT terminal to the starter solenoid.

However, I'd be concerned about your 1-2-Both switch. The Sterling Alternator-to-Battery Charger has 2 separate outputs, one for domestic batteries, one for starter battery. These outputs are at different voltages. Had you thought about the effect of using the 1-2-Both switch? It would be worth checking with Sterling that the charger won't be damaged by joining the 2 separate outputs (this is what would happen in the "Both" position).

For the sake of completeness, I'd add that I dislike 1-2-Both switches intensely, and that you'd be better off just having two simple on/off switches - one to isolate the engine battery, one to isolate the domestic batteries. As the Sterling Alternator-to-Battery Charger contains a blocking diode system, you'd then have no risk of accidentally discharging your starter battery.

 

[Dave_Rolfe]

Ken - Thanks for that info. I finally managed to work it out but it's so good to have someone confirm it.

PVB - I have wired the Sterling unit up completely separate to exclude the battery switch, running cables directly from the Sterlingg unit to the batteries. This means that it can charge as it is designed to, the battery switch just distributes the power from the batteries. Charles Sterling has confirmed this is OK.

Thanks for all your help on this subject, I think I'm just about there now.