Yanmar 3YM30 wiring on 36i (2007)
Oct 25, 2014 4:09:11 GMT
Post by so36idavid on Oct 25, 2014 4:09:11 GMT
My boat has a Yanmar 3YM30, 2007. I have just finished a project replacing all of the wiring for the high current path from the alternator to the batteries, including the grounds. I first detected a problem when I installed a Victron battery monitor and noticed that with my 200 Ah house bank 50% discharged I was only getting 30A out of what is supposed to be a 60A alternator. An investigation turned up the fact that the voltage at the batteries was 13.2V but the voltage at the alternator was 14.3V. It's an internally regulated alternator with no sense of the battery voltage. This drop of over a volt between the alternator and the batteries meant that the batteries would not accept as much amperage as the alternator could put out. Tracing the voltage drop showed a bunch of small drops on the wires and each of the (copious) connections on the charging path.
Most egregious were a bunch of skinny wires on the engine itself, between the alternator and the starting solenoid, and the ground. These look like 8 or 10 gauge wires to me. Here's a picture of a wire that I pulled off of the engine, next to the gauge of wire that replaced it (2 gauge). I don't know who wired up this engine, either Yanmar or Jeanneau, but whoever it was was negligent in the interest of saving literally a dollar. There's no way you should be putting 50+ amps through a wire like that and indeed it showed some signs of overheating. There are also fairly skinny wires downstream, leading to the isolation solenoid. That's definitely Jeanneau's fault. I also happened to notice that the fat wires had fine copper strands, but were not tinned, another no-no. Particularly since the heat shrink that was used to seal the terminals was not adhesive lined. So those wires were one salt water dousing away from turning into a corroded, green resistor. While I was at it I replaced the isolation solenoid with one rated at 100A continuous in case I ever decide to upgrade the alternator.
I don't know if this wiring is typical of this generation of boats/engines, or just this model, but you may want to take a look at the back of your alternator the next time you're checking out your engine. Also if you're not getting the amps out of your alternator that you expect, this might be one place to start.
David
P.S. On my engine the injection elbow is directly above the engine ground terminal, so a leaking injection elbow will rain hot salty water onto the boat's main ground connection along with an engine mount. Just another reason to periodically replace the injection elbow. I also smear dielectric grease on the area to prevent corrosion.
Most egregious were a bunch of skinny wires on the engine itself, between the alternator and the starting solenoid, and the ground. These look like 8 or 10 gauge wires to me. Here's a picture of a wire that I pulled off of the engine, next to the gauge of wire that replaced it (2 gauge). I don't know who wired up this engine, either Yanmar or Jeanneau, but whoever it was was negligent in the interest of saving literally a dollar. There's no way you should be putting 50+ amps through a wire like that and indeed it showed some signs of overheating. There are also fairly skinny wires downstream, leading to the isolation solenoid. That's definitely Jeanneau's fault. I also happened to notice that the fat wires had fine copper strands, but were not tinned, another no-no. Particularly since the heat shrink that was used to seal the terminals was not adhesive lined. So those wires were one salt water dousing away from turning into a corroded, green resistor. While I was at it I replaced the isolation solenoid with one rated at 100A continuous in case I ever decide to upgrade the alternator.
I don't know if this wiring is typical of this generation of boats/engines, or just this model, but you may want to take a look at the back of your alternator the next time you're checking out your engine. Also if you're not getting the amps out of your alternator that you expect, this might be one place to start.
David
P.S. On my engine the injection elbow is directly above the engine ground terminal, so a leaking injection elbow will rain hot salty water onto the boat's main ground connection along with an engine mount. Just another reason to periodically replace the injection elbow. I also smear dielectric grease on the area to prevent corrosion.