Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 19-04-2018, 08:29   #1
Registered User
 
Stillwater1's Avatar

Join Date: Apr 2014
Location: Florida West Coast
Boat: Watkins W27
Posts: 26
Send a message via Skype™ to Stillwater1
Alternator wiring question

My Yanmar 2GMF20 is being rebuilt. I decided to upgrade the fuel and electrical systems while that is being done. The old Yanmar panel and wiring harness were not the correct ones for the motor so I decided to build my own panel, harness and connections.

FYI, my engine start battery and my house bank do not connect to each other. The house bank is solar charged only. The SLA start battery will be charged by the alternator when the engine is running, and kept topped off by a 40w solar panel with it's own charge controller when not.

The question is the alternator wiring. I am replacing the alternator with another Hitachi style unit. Pictures are attached. I found this info:

E = ground (DC negative) I will connect to my negative bus bar
B+ = Battery (DC Positive) I will connect to my battery directly
P = tachometer send

Question 1 is: do I need to also connect the Green and Yellow wires from the T style connector, or no?

Question 2: do you see any other issues I should be aware of?

I am sending pics of all the new stuff so you can see how I am doing this, absent all the other wires used by the original Yanmar harness.
(FYi, the engine alarm components are not yet installed)

Thanks,

Bob
Attached Thumbnails
Click image for larger version

Name:	New Altenator.jpg
Views:	2468
Size:	383.1 KB
ID:	168391   Click image for larger version

Name:	PanelFrontSmall.jpg
Views:	385
Size:	226.7 KB
ID:	168392  

Click image for larger version

Name:	PanelRearSmall.jpg
Views:	474
Size:	251.7 KB
ID:	168393   Click image for larger version

Name:	EnginePanelSmall.jpg
Views:	517
Size:	323.6 KB
ID:	168394  

Stillwater1 is offline   Reply With Quote
Old 19-04-2018, 11:34   #2
Registered User

Join Date: Apr 2007
Location: Australia
Boat: Island Packet 40
Posts: 6,416
Images: 7
Re: Alternator wiring question

On the Bosch alternators I use the T connection is for voltage sensing and the charge warning light.
RaymondR is online now   Reply With Quote
Old 19-04-2018, 13:08   #3
Registered User

Join Date: Aug 2015
Location: Sozopol
Boat: Riva 48
Posts: 1,375
Re: Alternator wiring question

Have a look at this Yanmar wiring diagram, it will help you figure out the connections. Stock Yanmar 2GM20 does not have continuous pressure and temp sensor outputs. The sensors are just on/off switches. You can either install additional sensors to feed your gauges or remove the gauges and install warning light. I think warning lights are simpler and more efficient.

One other idea is to create a much smaller panel. You only need the tach and three warning lights around the tach. I have been thinking about installing a chartplotter in the space for the instrument panel and moving the tach/warning lights elsewhere. You also need a buzzer which is much more important than the warning lights in my opinion.

SV Pizzazz
Attached Thumbnails
Click image for larger version

Name:	Yanmar wiring.jpg
Views:	2891
Size:	76.4 KB
ID:	168400  
Pizzazz is offline   Reply With Quote
Old 19-04-2018, 14:27   #4
Registered User

Join Date: Nov 2013
Location: Slidell, La.
Boat: Morgan Classic 33
Posts: 2,845
Re: Alternator wiring question

Don't know for sure. looks like you have a 12288N alternator, found this online





which seems to indicate that the yellow wire is a regulating wire and should be hooked to the charging terminal, while the green should be hooked to the voltmeter.

How far is your start battery from the alternator?

Typically the charge wire is hooked to the main starter cable at the starter, and charges back through that cable, which eliminates the need for an extra, long 6 gauge or so wire from the charging terminal to the battery; simpler and less expensive.
jimbunyard is offline   Reply With Quote
Old 19-04-2018, 15:18   #5
Registered User
 
Stillwater1's Avatar

Join Date: Apr 2014
Location: Florida West Coast
Boat: Watkins W27
Posts: 26
Send a message via Skype™ to Stillwater1
Re: Alternator wiring question

All: Thanks for the useful info, esp. the drawings. I will study them more tomorrow, but I believe they will answer my questions.
Pizzazz: I have always liked having gauges, just a thing with me. The old set up included a temp and oil pressure gauge. I have the correct sensors for the new ones. I am going to reuse or replace the old on/off sensors to activate a new buzzer, the old one did not work. As for warning lights, maybe, for triple redundancy, we will see. The location in the cockpit of the old panel meant when seated on the port side of the boat (it has a tiller, not a wheel) you could not see them, so a new location would have to be determined to make them useful.
Jim: the battery is about 4 feet away. I was going to run the B+ wire to the new fuse panel on the engine bay wall, but going to the starter main cable post makes more sense, and in looking at the old harness I think that is how it was done.
Stillwater1 is offline   Reply With Quote
Old 19-04-2018, 15:23   #6
Registered User

Join Date: Nov 2013
Location: Slidell, La.
Boat: Morgan Classic 33
Posts: 2,845
Re: Alternator wiring question

On second thought, there's some more, conflicting information here

http://www.cruisersforum.com/forums/...ed-131133.html

I would ask either someone at the place you got it from, or if you don't trust them, call or go to a good alternator repair shop and ask them. If I couldn't get some information I trusted, I would hook up just the charge wire, run it and see what happens. As long as you have a place for the power to go, i.e. a positive cable to the battery, you won't pop the diodes. While the engine's running, test the output terminal for more that 13.5 volts and then check the voltage on the green and yellow wires.

If the alternator isn't putting out, it is likely that one of the wires is an excite wire, and should be hooked into an on/off switch in some manner, usually incorporated into the starter switch.
jimbunyard is offline   Reply With Quote
Old 19-04-2018, 15:32   #7
Moderator and Certifiable Refitter
 
Wotname's Avatar

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 20,242
Re: Alternator wiring question

Quote:
Originally Posted by Stillwater1 View Post
..........

The question is the alternator wiring. I am replacing the alternator with another Hitachi style unit. Pictures are attached. I found this info:

E = ground (DC negative) I will connect to my negative bus bar
B+ = Battery (DC Positive) I will connect to my battery directly
P = tachometer send

Question 1 is: do I need to also connect the Green and Yellow wires from the T style connector, or no?

.....
Thanks,

Bob
Yes, one of those wires will need to be connected otherwise the alternator will not deliver any volts. I think it is the yellow one but right now I am only going on memory...

It may be connected direct to the B+ (like JimB suggested) which means the alternator will be operating any time it is spinning or it maybe connected via the engine off/on/start switch (to the "on" terminal) which means the alternator will operate only when the switch is "on". FWIW This is also the way the Yanmar panel works.

The other wire (presumably green) need not be connected if you are foregoing the alternator "charge" light.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 20-04-2018, 13:37   #8
֍֎֍֎֍֎֍֎֍֎

Join Date: Apr 2006
Posts: 15,136
Re: Alternator wiring question

"Yes, one of those wires will need to be connected otherwise the alternator will not deliver any volts. I think it is the yellow one but right now I am only going on memory...

....The other wire (presumably green) need not be connected if you are foregoing the alternator "charge" light."

I think not. The diagram shows the green wire can have an optional "charge" indicator bulb--but that is in parallel with a resistor. In typical automotive systems, they just use a light bulb as the resistor (which is problematic if the bulb burns out). The idea is that the resistor (or bulb) allows some power to be on this line IF THE KEY IS ON. So the alternator is only turned on when the engine is running, that's why it shows a connection to a "run hot" which we could call "ignition hot" in the US. A line that gets power any time the ignition/engine is in the "RUN" position.

(And no, I haven't tried to look over the whole thing, just saw that one right up.)
hellosailor is offline   Reply With Quote
Old 20-04-2018, 23:37   #9
Registered User

Join Date: Apr 2007
Location: Australia
Boat: Island Packet 40
Posts: 6,416
Images: 7
Re: Alternator wiring question

The Y/W lead is the voltage sensing connection to the regulator and it is used to sense the voltage level at the battery terminal. If you sense the voltage level at the alternator output and have resistance in the charging lead between alternator output and battery terminal it will result in the regulator tapering down the charging current before the battery is fully charged and you will only get a lesser charging current.

The LG/R lead provides a small current to the regulator to allow it to sufficiently activate the field coil on the rotor to provide a small level of magnetization to the field rotor in order for current generation to commence. Once a current is generated in the main coils the regulator takes it's current source through the W/BK connection.

The resister is there in case the indicator light goes open circuit.
RaymondR is online now   Reply With Quote
Old 18-02-2022, 23:34   #10
Registered User

Join Date: Dec 2019
Location: Scituate MA
Boat: Cal 29-2
Posts: 53
Images: 1
Re: Alternator wiring question

I want to add some commentary for those with similar questions. I ran into a similar situation with friend’s boat. The Hitachi design has two pathways for excitation to start the alternator generating, the L circuit that uses an external incandescent lamp (200-300mA is required) or the R circuit connected to the switched ignition plus. We found my friends boat had no lamp circuit consideration so the original was dependent on the R circuit for excitation. When he installed the clone alternator unit, it was apparently designed to use the L circuit so it wouldn’t excite. We installed a small truck clearance light in the cabin to operate the L circuit and provide indication. As the bulb is only lit for short periods, it should outlast most of us. The lamp could be replaced by a resistor.
One other difference for most clones is they use case grounding for B- where the Hitachi B- is floating.
BTW: once excited, you could shut off the ignition and a true Hitachi alternator keeps charging as the internal regulator is powered by the auxiliary diodes; you can’t halt charging until the engine stops. I’m referring to the 35/55/80A units of about 20 years back.
Attached Thumbnails
Click image for larger version

Name:	F674A6A2-BC75-4E3E-90AF-2C753F610D25.jpeg
Views:	2701
Size:	108.1 KB
ID:	253192   Click image for larger version

Name:	61DC22B4-0B78-4696-9F26-04AEC240F761.jpg
Views:	345
Size:	340.3 KB
ID:	253193  

Dalestr is offline   Reply With Quote
Old 22-02-2022, 13:06   #11
Registered User
 
d design's Avatar

Join Date: Oct 2013
Location: Whangaroa, New Zealand
Posts: 266
Re: Alternator wiring question

Make sure you hook up the sense lead to the correct battery else you may create a sulfuric acid vape machine.
d design is offline   Reply With Quote
Old 23-02-2022, 08:52   #12
Registered User

Join Date: Dec 2019
Location: Scituate MA
Boat: Cal 29-2
Posts: 53
Images: 1
Re: Alternator wiring question

My prior schematic was not legible so trying again. This schematic is one of those items that Yanmar bungled in an otherwise excellent Shop Manual.
The schematic above from jimbunyard is useful but quite different from Hitachi. The "3G" labels it as a Ford alternator and the terminals shown, S,I,A,B, were used for for an external regulator with Stator, Ignition, Armature, and Battery terminals but the drawing somehow suggests an internal regulator.
An Hitachi alternator that is operated with an internal regulator as shown here senses its output voltage internally at the "L" node of the regulator. The voltage there happens to match the output voltage at "BAT". At the battery, voltage will be reduced depending on the current and wiring resistance.
R1 of the schematic (at the R terminal of alternator connector) emulates the lamp resistance used in the "L" circuit so either or both can be used for excitation. d_design is correct that for an external regulator, the regulator's Vsense and Ignition + should always connect to the same battery. With an internal regulator there is internal sensing so issue is less dangerous but still should be avoided.
Attached Thumbnails
Click image for larger version

Name:	Hitachi 55A schematic corrected.jpg
Views:	2184
Size:	172.9 KB
ID:	253422  
Dalestr is offline   Reply With Quote
Reply

Tags
alternator, wiring

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Alternator and starter wiring question..... w32honu Electrical: Batteries, Generators & Solar 1 05-03-2018 11:44
Wiring Xantrex 1800 watt inverter wiring geoleo Electrical: Batteries, Generators & Solar 12 04-10-2016 08:38
Yanmar 1gm10 alternator wiring question johnlikesail Engines and Propulsion Systems 44 01-04-2016 21:42
Help Needed! - Wiring Alternator to Charge House Batteries cgaskell Electrical: Batteries, Generators & Solar 6 04-04-2010 15:09
Alternator - Installation Wiring Connections jonww Electrical: Batteries, Generators & Solar 1 16-11-2009 20:39

Advertise Here


All times are GMT -7. The time now is 01:33.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.