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SVTatia 09-27-2012 11:13 PM

Alternator Output Wire
 
In the DC wiring diagrams, I see the mention of Alternator Output wire, but I cannot find this wire on my engine.
In the Westerbeke wiring schematic the AO goes to the starter, so I assume the alternator output wire is connected to the starter solenoid and the heavy starter wire is the one that I connect to the battery for starting and charging? Or, do I need to have a separate cable from the Alternator to the battery?

Maine Sail 09-27-2012 11:53 PM

Re: Alternator Output Wire
 
Quote:

Originally Posted by SVTatia (Post 927496)
In the DC wiring diagrams, I see the mention of Alternator Output wire, but I cannot find this wire on my engine.
In the Westerbeke wiring schematic the AO goes to the starter, so I assume the alternator output wire is connected to the starter solenoid and the heavy starter wire is the one that I connect to the battery for starting and charging? Or, do I need to have a separate cable from the Alternator to the battery?

That is the path to the batteries on many "factory wired" engines. A dedicated wire direct to the house bank is preferred by many. One benefit is that it eliminates the possibility of frying the diodes by turning the batt switch off with the motor running. On the drawback side a fuse now has to be added close to the battery bank and a "service switch" or other means of easy disconnect should be available so you don't get zapped with the battery switch off and the alt still "powered"..

SVTatia 09-28-2012 08:57 AM

Re: Alternator Output Wire
 
Thank you Maine Sail. My plan is to make the Battery Switch a use switch as per your recommendation on “1/BOTH/2/OFF Switches Thoughts & Musings” post – to quote you:
“To make your 1/BOTH/2/OFF a "USE SWITCH" simply:

1- Make your house bank #1, or "primary"
2- Make the start/reserve battery #2 or "back up/secondary"
3- Install an Automatic Combining Relay (VSR) or an Echo Charger to charge bank #2.
4- (Bonus Option) Feed alternator output directly to the house bank.”

What I am trying to accomplish is to wire the alternator/starter directly to the battery, bypassing the switch - making the house bank the engine starting battery and make the charging “always on” with a VSR to the reserve battery.
Since my alternator output and starter share the same cable, can I route this cable that is now starter/alternator directly to the house bank to comply with your item 4 above?
Else I would have to find a way to wire a separate alternator output wire to the battery.
Thanks

fairbank56 09-28-2012 09:28 AM

Re: Alternator Output Wire
 
Quote:

Originally Posted by SVTatia (Post 927568)
What I am trying to accomplish is to wire the alternator/starter directly to the battery, bypassing the switch

While a battery disconnect switch is only an ABYC requirement for batteries with a CCA greater than 800 amps, I strongly suggest NOT bypassing the switch and connecting your battery directly to the starter. A potentially huge safety issue in my opinion.

Eric

Maine Sail 09-28-2012 09:54 AM

Re: Alternator Output Wire
 
Quote:

Originally Posted by fairbank56 (Post 927579)
While a battery disconnect switch is only an ABYC requirement for batteries with a CCA greater than 800 amps, I strongly suggest NOT bypassing the switch and connecting your battery directly to the starter. A potentially huge safety issue in my opinion.

Eric


I suspect he only meant running the alt direct to the batt bank but typed starter... I agree 150% that a starter battery should ALWAYS have a switch. Never understood why less than 800CCA would not burn your boat down or was any safer than 801CCA...? Course I also fuse most starter circuits too especially on small AUX engines.

This happened with FAR LESS than 800CCA and with no fuse and no switch there was no way to stop the electrical fire....
http://www.pbase.com/mainecruising/image/128377865.jpg

Stu Jackson 09-28-2012 12:21 PM

Re: Alternator Output Wire
 
Tatia, here's the WHY of how the boats were wired with one wire from the 1-2-B switch C post to the alternator and starter. When you route your AO to the house bank, you need to use a NEW wire, and disconnect the small wire between the starter and alternator.

OEM 1-2-B Switch Wiring History Alternator/Batteries & "The Basic" 1-2-B Switch BEST Wiring Diagrams

It was also discussed in Maine Sail's article.

asdf38 09-28-2012 02:20 PM

Re: Alternator Output Wire
 
Quote:

Originally Posted by SVTatia (Post 927568)
Thank you Maine Sail. My plan is to make the Battery Switch a use switch as per your recommendation on “1/BOTH/2/OFF Switches Thoughts & Musings” post – to quote you:
“To make your 1/BOTH/2/OFF a "USE SWITCH" simply:

1- Make your house bank #1, or "primary"
2- Make the start/reserve battery #2 or "back up/secondary"
3- Install an Automatic Combining Relay (VSR) or an Echo Charger to charge bank #2.
4- (Bonus Option) Feed alternator output directly to the house bank.”

What I am trying to accomplish is to wire the alternator/starter directly to the battery, bypassing the switch - making the house bank the engine starting battery and make the charging “always on” with a VSR to the reserve battery.
Since my alternator output and starter share the same cable, can I route this cable that is now starter/alternator directly to the house bank to comply with your item 4 above?
Else I would have to find a way to wire a separate alternator output wire to the battery.
Thanks

It's a great setup, I moved to this configuration this season. I used the blue sea ACR (Relay). If I did it over I'd use an echo charger simply because the echo limits current and can be wired to the start/reserve bank with smaller wire - wrestling battery cabling around is a huge pain.

On the other hand the battery switch provides connections to both banks in one place already so if the relay is mounted in that area its leads can be small. Also the Blue-Sea ACR has an indicator LED output which tells me when it (and the alternator) are working properly. I don't know if the echo has this nice output.

SVTatia 09-28-2012 03:43 PM

Re: Alternator Output Wire
 
Maine Sail, Fairbank56, Stu Jackson, asdf38

Many thanks for your responses – you have removed the doubts and I am now clearer about how to do this. Thanks for the link Stu.
Great education - you guys rock!

SVTatia 06-04-2013 10:57 PM

Re: Alternator Output Wire - what size?
 
I had to revive this post because I am now actually doing this.

The alternator output post a #8 screw where the 10awg wire is connected with a ring and routed to the starter - a very short run.
When I wire this to the battery, the distance is about 12 feet, and I was planning to use 4awg cable.
I am not sure how I will attach a lug or ring to this 4# cable to connect to the much smaller #8 bolt on the alternator. Any ideas?

Thanks

mitiempo 06-04-2013 10:59 PM

Re: Alternator Output Wire
 
Lugs for 4 awg are available with holes as small as a #10.


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