What is this 4th wire on alternator?

[IBX_NC]

I'm replacing a Volvo Penta TAMD74EDC 24v alternator and when I received a "compatible" replacement, it is missing a 4th wire which comes out of the regulator. The photo is my existing alternator; the D+ and B+ wires have already been removed. I'm assuming the small gauge red wire coming out of the regulator is voltage monitor to my helm monitor/light. Can anyone confirm? If so, can I just place this wire on the B+ terminal?

[Shrew]

Hopefully this helps.

https://conquerallelectrical.ca/alte..._an_alternator

Terminal....Definition.......................Notes
A..................Battery........................ ...Battery positive connection
B..................Battery........................ ...Battery positive connection
B+................Battery......................... ..Battery positive connection
C..................Center......................... ...Centre point of a Y stator
COM.............Conputer.........................C omputer Connection
D+...............Warning light....................Comes from the old ‘Dynamo Positive’ on a generator
DFM.............Dynamo Field Modulation..Duty Cycle signal from the ECU
E..................Warning light...................Comes from the word ‘Excitation’
F..................Field.......................... ....For externally regulated alternators
FR................Field Regulation..............Voltage Signal from the ECU
G.................Ground.......................... Chassis negative connection
I..................Inidcator...................... ...Warning Lamp
L..................Lamp........................... ..Warning Lamp
M.................Field........................... ...Found on older Externally Regulated units
N.................Neutral......................... .Centre point of a Y-connected stator
P..................Pulse.......................... ...Stator connection for tachometer
R.................Relay........................... ..Output to charge relays, etc
S.................Sense........................... .Battery Voltage sense wire
S (FORD)......Stator............................Stat or Pulse. Used for tachometers
T..................Tach Stator Pulse............Used for tachometers
W.................Waveform Stator Pulse.....Used for tachometers

[team karst]

Probably the voltage wire that the regulator uses to sense either remote or local B+. If you are not worried about wire Vdrop, attach to B+ stud. OTOH, if the big red wire going to load/battery is more than several feet away, this reg red wire goes to that remote point. NOT usually to the helm.

btw, it just so happens i did a VP alternator job today with remote sense active. Works well.

[IBX_NC]

Originally Posted by team karst

Probably the voltage wire that the regulator uses to sense either remote or local B+. If you are not worried about wire Vdrop, attach to B+ stud. OTOH, if the big red wire going to load/battery is more than several feet away, this reg red wire goes to that remote point. NOT usually to the helm.

btw, it just so happens i did a VP alternator job today with remote sense active. Works well.

I'm convinced it is a voltage sense wire coming from the battery-side of the isolators. They are about 20' away (it measures ~26VDC with engines off). I'm having difficulty finding 24v remote sense alternators. What did you use?

[team karst]

Gotta pix of replacement alt? Mine had a short yellow wire as sense wire headed for the built-in regulator.

[IBX_NC]

Originally Posted by team karst

Gotta pix of replacement alt? Mine had a short yellow wire as sense wire headed for the built-in regulator.

Not at home; I'll post one tomorrow.

[IBX_NC]

Here is a pic of the replacement, listed as compatible with TAMD74. Note the lack of remote sense wire from the earlier pic of the existing. When I took a look under the regulator, there are the typical 4 wires, two on the main stator, two to the excitor stator. My existing alternator has an add'l remote sense wire going to the regulator. So, the replacement is voltage, amperage and bolt pattern compatible, just not application compatible.

@team_karst, if you have a model that you used on the VP job, I'd appreciate the lead.

[team karst]

Mine was 12V system. You might check with Rare Electric for possibilities.

[nigel1]

Picture of a similar alternator I fitted to my Volvo Penta TMD22, 12V system.

Yellow wire is the sense wire


In this picture, the sense wire is connected to the B+ terminal, in my case I have the sense wire connected to the battery bank.


Alternator is a VALEO A13N234

[nigel1]

Originally Posted by IBX_NC

Here is a pic of the replacement, listed as compatible with TAMD74. Note the lack of remote sense wire from the earlier pic of the existing. When I took a look under the regulator, there are the typical 4 wires, two on the main stator, two to the excitor stator. My existing alternator has an add'l remote sense wire going to the regulator. So, the replacement is voltage, amperage and bolt pattern compatible, just not application compatible.

@team_karst, if you have a model that you used on the VP job, I'd appreciate the lead.

Ask the supplier to provide the regulator with the sense wire.
Think they cost about $25

[hpeer]

Originally Posted by Shrew

Hopefully this helps.

https://conquerallelectrical.ca/alte..._an_alternator

Terminal....Definition.......................Notes
A..................Battery........................ ...Battery positive connection
B..................Battery........................ ...Battery positive connection
B+................Battery......................... ..Battery positive connection
C..................Center......................... ...Centre point of a Y stator
COM.............Conputer.........................C omputer Connection
D+...............Warning light....................Comes from the old ‘Dynamo Positive’ on a generator
DFM.............Dynamo Field Modulation..Duty Cycle signal from the ECU
E..................Warning light...................Comes from the word ‘Excitation’
F..................Field.......................... ....For externally regulated alternators
FR................Field Regulation..............Voltage Signal from the ECU
G.................Ground.......................... Chassis negative connection
I..................Inidcator...................... ...Warning Lamp
L..................Lamp........................... ..Warning Lamp
M.................Field........................... ...Found on older Externally Regulated units
N.................Neutral......................... .Centre point of a Y-connected stator
P..................Pulse.......................... ...Stator connection for tachometer
R.................Relay........................... ..Output to charge relays, etc
S.................Sense........................... .Battery Voltage sense wire
S (FORD)......Stator............................Stat or Pulse. Used for tachometers
T..................Tach Stator Pulse............Used for tachometers
W.................Waveform Stator Pulse.....Used for tachometers

Thankyou.0