Alternator

SycloneDriver

SycloneDriver

.
Jul 23, 2009
912
Beneteau 31 Oceanis Grand Lake, Oklahoma
This isn't rocket science people.
The alternator output probably connects to the starter lug or maybe the battery switch. The alternator sounds like it has an extra ground wire attached. Years ago I added an extra ground wire on a car to reduce the voltage drop, easy, cheap and it worked. I'm thinking about doing the same on my boat but I want to measure the voltage drop first.
The charger needs replaced, easy.
Post some more photos and I'm sure this can all be cleared up.
 
Voyager1

Voyager1

.
Oct 29, 2017
89
ODay 302 Kenosha WI
Did I bit more digging, that black wire goes back to my electric panel landing on the DC ground bus. Was able to Ohm it. The alternator bat wire I am pretty certain is crimped with the starter wire. Is there advantages or disadvantages to running the ground back to the electrical panel.

Thanks for all the responses, I will plan on replacing the battery charger and yes clean the terminals. Feeling a bit better on my understanding of this.
 
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dlochner

.
Jan 11, 2014
12,961
Sabre 362 113 Fair Haven, NY
Voyager1 said:
Did I bit more digging, that black wire goes back to my electric panel landing on the DC ground bus.
Click to expand
The DC ground bus needs to get back to the battery somehow. The DC Negative/ground from the battery needs to connect to the common ground on the engine block.

I'm thinking a better solution is to connect the DC negative bus bar directly to the engine ground rather than the battery. Although I can't give a good cogent reason why I think so. If the boat had an outboard or no engine, then the way it is wired would be fine because there is no engine block to ground to. I think my concern is routing the DC negative back through the battery before it is grounded to the engine block. Something seems funky about doing it that way. This is an @Maine Sail technical question.

If this were my boat, I would route the DC ground from the busbar behind the panel to a DC busbar, connect the negative to the busbar, and then connect the busbar to the Engine ground.
 
smokey73

smokey73

.
Oct 26, 2010
2,143
Hunter 40.5 Beaufort, SC
Just a guess but: the OP says there are two red wires from the charger to the positive terminals. He said the white wire landed on the negative terminal also goes to the battery charger. Is it possible that the white wire is a temperature compensation sensor? That would be my guess at least. Does'nt a temp comp sensor wire go the the negative terminal - it does on my boat.
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,155
CAL 35 Cruiser #21 moored EVERETT WA
@smokey73 You are correct that a temp sensor is connected to a battery terminal. There would be a "thermistor" on the white wire if it was temp sensor. That wire is not a temp sensor.

If @Voyager1 was to buy a Sterling 12V 30Amp Pro Charger Ultra Lite then...
Here a picture of the Sterling Pro Charger connections. The Temp sensor is listed on the upper right side of the board. The wire is run down to the Negative terminal of the battery.
1572821633232.png
 
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dlochner

.
Jan 11, 2014
12,961
Sabre 362 113 Fair Haven, NY
smokey73 said:
Just a guess but: the OP says there are two red wires from the charger to the positive terminals. He said the white wire landed on the negative terminal also goes to the battery charger. Is it possible that the white wire is a temperature compensation sensor? That would be my guess at least. Does'nt a temp comp sensor wire go the the negative terminal - it does on my boat.
Click to expand
He said there were 2 red wires, one white. No black. So there has to be a DC negative for the charger, it must be the white wire. The boat is also old enough that ABYC standards weren't clear on color coding wires or who knows what prior owners have done.
 
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smokey73

smokey73

.
Oct 26, 2010
2,143
Hunter 40.5 Beaufort, SC
Of course mine is a newer charger but since the OP indicated that there was a white wire on the negative terminal I was only posing the question. I have a white wire as shown on jssalem's wiring diagram. Without the make and the model of the charger we are all just guessing until the OP traces out the wires. I'm still voting for some sort of wire for temperature compensation.
 
Davidasailor26

Davidasailor26

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May 17, 2004
5,684
Beneteau Oceanis 37 Havre de Grace
smokey73 said:
Without the make and the model of the charger we are all just guessing until the OP traces out the wires. I'm still voting for some sort of wire for temperature compensation.
Click to expand
See post #11 of the thread. Looks unlikely to have temp compensation.
 
Ron20324

Ron20324

.
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
dlochner said:
... If this were my boat, I would route the DC ground from the busbar behind the panel to a DC busbar, connect the negative to the busbar, and then connect the busbar to the Engine ground.
Click to expand
+1. You should not consider the engine as an electrical conductor.
 
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