I need to pick off 12v from the Yanmar ignition system to activate a low-power (30mA coil) relay when the switch is turned on. Engine is 4JH-TE with original 55amp Hitachi alternator. As I read the service manual, the easiest place to to this is on the line to the "R" terminal on the regulator (that's on the top of the T configuration of the two control lines to the regulator). It would be really convenient to do this right at the alternator. Can anyone verify this for me, or suggest where else on the harness I might splice a line? Thanks, Derek
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Ed Schenck
Think you are right. . . . .
Derek. When I replaced my Hitachi 35 with a 55 I needed an exciter voltage. Pretty certain it is the post on the alternator with a 'T' shape. My boat has a separate starter pushbutton. That wire goes to a relay that I installed to help the starter solenoid. From that relay post I ran a wire to the alternator 'T' post for the exciter voltage. But that is just an instantaneous thing. Is that what you are looking for?
Derek. When I replaced my Hitachi 35 with a 55 I needed an exciter voltage. Pretty certain it is the post on the alternator with a 'T' shape. My boat has a separate starter pushbutton. That wire goes to a relay that I installed to help the starter solenoid. From that relay post I ran a wire to the alternator 'T' post for the exciter voltage. But that is just an instantaneous thing. Is that what you are looking for?
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Derek Rowell
Here's what I'm doing....
Ed, I've just installed a separate starter battery. Because it is tucked away I am using a remote disconnect switch (Blue Sea 9012) to save long cables. I want to activate the remote switch (i.e. turn on the starter battery) when I turn the ignition on. Blue Sea suggest doing it that way - so I need 12v that is on when the switch is turned on.
Ed, I've just installed a separate starter battery. Because it is tucked away I am using a remote disconnect switch (Blue Sea 9012) to save long cables. I want to activate the remote switch (i.e. turn on the starter battery) when I turn the ignition on. Blue Sea suggest doing it that way - so I need 12v that is on when the switch is turned on.
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John Visser
Might not accomplish goal
Not criticizing, just curious about your design. I stilll stay up at night turning this stuff over in my head. If the house and starter batteries are tied together when the ignition is turned on, and the house is discharged, your start battery will immediately start discharging into the house bank. This might be a problem. What I did was to connect the start battery directly to the starter. The engine electrical circuit power, as for paanel and glow plug, are distributed from the starter terminal. The alternator output goes directly to the house bank. A relay that senses the presence of a charging source (by voltage level detection) connects the house to the start battery. Since this is voltage-level controlled, with a dead house bank, the relay won't come on until the house is charged up enough for the voltage to come up (this is normally immediate). The only extra long wire was from the start battery to the house bank. However, you could put the relay in the engine compartment between the starter terminal and the alternator output terminal, and save that long wire. Maybe you could energize your relay with the alternator "on" signal, or the oil pressure switch. West Marine sells a relatively inexpensive relay-based battery combiner that will serve this purpose well. Let me know what you think. jv
Not criticizing, just curious about your design. I stilll stay up at night turning this stuff over in my head. If the house and starter batteries are tied together when the ignition is turned on, and the house is discharged, your start battery will immediately start discharging into the house bank. This might be a problem. What I did was to connect the start battery directly to the starter. The engine electrical circuit power, as for paanel and glow plug, are distributed from the starter terminal. The alternator output goes directly to the house bank. A relay that senses the presence of a charging source (by voltage level detection) connects the house to the start battery. Since this is voltage-level controlled, with a dead house bank, the relay won't come on until the house is charged up enough for the voltage to come up (this is normally immediate). The only extra long wire was from the start battery to the house bank. However, you could put the relay in the engine compartment between the starter terminal and the alternator output terminal, and save that long wire. Maybe you could energize your relay with the alternator "on" signal, or the oil pressure switch. West Marine sells a relatively inexpensive relay-based battery combiner that will serve this purpose well. Let me know what you think. jv
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Ed Schenck
Too complicated. . .
for my feeble mind. John, I can see why you lose sleep. See Related Link for Derek's wiring diagram. I have trouble seeing the advantage unless the wire from the 9012 to the starter is of a lighter gauge. Mine is the old fashioned way, AGM starter to battery switch #1 and house gels to #2. Then the battery switch output goes to the starter. Whenever I am on the boat the switch is on #2 whether on shorepower, motoring, sailing, or anchored. Pos. #1 is strictly backup. A combiner makes sure that the AGM stays charged. But I check it often with the Link 2000.
for my feeble mind. John, I can see why you lose sleep. See Related Link for Derek's wiring diagram. I have trouble seeing the advantage unless the wire from the 9012 to the starter is of a lighter gauge. Mine is the old fashioned way, AGM starter to battery switch #1 and house gels to #2. Then the battery switch output goes to the starter. Whenever I am on the boat the switch is on #2 whether on shorepower, motoring, sailing, or anchored. Pos. #1 is strictly backup. A combiner makes sure that the AGM stays charged. But I check it often with the Link 2000.
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Derek Rowell
No, no, no...
It's not difficult at all - in fact it is very simple. The house and starter batteries are separated. The starter battery is connected ONLY to the starter motor, unless being charged. The alternator and charger are connected directly to the house bank and thus it is charged first. There is a combiner with a threshold of 13.7 volts that will automatically parallel the batteries when the house bank is charged to 13.7 volts. The starter battery should be nearly at full charge all the time, and therefore there is no danger of the starter battery discharging into a depleted house bank. That's not what I was talking about however in my post. What I am installing is the "disconnect" switch on the starter bank. It does not parallel the batteries - just isolates the starter motor from the battery. All batteries on a boat must have such a switch.
It's not difficult at all - in fact it is very simple. The house and starter batteries are separated. The starter battery is connected ONLY to the starter motor, unless being charged. The alternator and charger are connected directly to the house bank and thus it is charged first. There is a combiner with a threshold of 13.7 volts that will automatically parallel the batteries when the house bank is charged to 13.7 volts. The starter battery should be nearly at full charge all the time, and therefore there is no danger of the starter battery discharging into a depleted house bank. That's not what I was talking about however in my post. What I am installing is the "disconnect" switch on the starter bank. It does not parallel the batteries - just isolates the starter motor from the battery. All batteries on a boat must have such a switch.
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John Visser
Got it
Derek, now I understand what you're doing. I like your design, and I agree that a disconnect is a good idea. I don't have a disconnect for teh starter battery installed yet, but I have teh switch - a high current SPST rotary - that I will install soon. I'm planning on putting it in the bulkhead that forms the enclosure for the starting battery. Thoe only thing that I'm doing differently is that I'm powering my engine panel, including the ignition switch circuits, with the starting battery - so your scheme wouldn't work for me, since I wouldn't be able to energize the remote switch for the start battery. jv
Derek, now I understand what you're doing. I like your design, and I agree that a disconnect is a good idea. I don't have a disconnect for teh starter battery installed yet, but I have teh switch - a high current SPST rotary - that I will install soon. I'm planning on putting it in the bulkhead that forms the enclosure for the starting battery. Thoe only thing that I'm doing differently is that I'm powering my engine panel, including the ignition switch circuits, with the starting battery - so your scheme wouldn't work for me, since I wouldn't be able to energize the remote switch for the start battery. jv
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