Alternator charge wire

[Brylk1830]

I'm just wondering where my alternator charge wire (wire that supplies battery with charge) is located on my 99 Merc 3 cylin 2 stroke 40 hp engine? If anyone has a wiring diagram or knows if the charging source is just connected with the starter/solenoid wiring I would appreciate it. Thanks!

[redtech]

the yellow wire coming from under the flywheel are the stator wire these feed the reg/rect a/c voltage for charging the red wire on the regulator is the battery charge wire this feeds back into the system and down to your start solinoid and then to the battery

[Brylk1830]

Thanks red, so ultimatley I need a were coming from my solenoid to the starting battery and then a wire coming from my alternator neg as a ground for my batt. This way, as long as I have my starting battery set up to be charged, I can connect another battery into the equation with a batt selector switch, relay, etc. and they will both get charged? Thanks again!

[murdomack]

Brylk1830

The current is already being fed back to your starter battery through the starter cable when the engine is running.
Your simplest solution is to buy the ACR and use that to charge your trolling battery automatically once your starter battery gets to 13.7 volts. You do not need to modify any of your existing wiring.
You can add switching later if you think it will be an improvement. You can have a powered switch that can open and close the relay or you can have a battery selector switch.
I would not buy any switch until I had the system up and running.
When you open the link below go to "view in annual catalogue", this gives a wiring diagram with an ON-OFF-Combine switch. Delete this switch from your plan and have the Battery positive wires going directly to the starter and the trolling motor. The ACR will look after the charging.
When you have tried it out and you are happy with the system you can then decide about switches.




http://www.westmarine.com/webapp/wcs...classNum=12106

[Brylk1830]

Thanks again murdomack, I definitely agree that the ACR would be the best bet to ensure my batteries are charged seperately. Luckily, my local West Marine shop even has one in stock!
I am worrying a bit, however, about how much I have to do yet and the cost of all the materials i've yet to purchase. As of now, I think I may just be going with a battery selector switch. I posted below the beginning of a rough wiring diagram that i'm making before I begin. I know it would probably be a good idea to install some type of isolater into the equation but for now I think i'm just going to go with the switch alone.
I have read numerous posts about the selector switches needing to be wired in with an isolater so I guess if buying the ACR is truly the logical down the road decision I may have to fold and go for it.
I guess my only concern now is what will be the repercussions for only using a battery selector switch and letting both batteries be charged simultaneously as the engine is running?

[Brylk1830]

Here's the diagram

[murdomack]

With the system you have at present you are getting enough amps to recharge your battery after you start up the engine. If you add a trolling motor battery that you have run down and join both batteries to charge simultaneously, the charge in your starter battery would drop until it balanced out with the flat one and the feed from the alternator/rectifier.

If your engine was stopped for any reason you may not have the power to start it again. does it have a manual start as a back-up?
Have you actually already got a selector switch? Is that why you keep referring to it? Is it an off-1-both-2 type? If you have one of these, you could recharge the starter battery for a while after a start and then switch over to the trolling battery but only if your switch makes before break, some of the older switches don't. I would not leave the batteries joined unless I could start the engine manually.

Without instruments to moniter the condition of the batteries, you would be guessing at best. Instruments cost money and need wiring in as well. This money would be better spent on an ACR.

There is also the danger of switching to the off position while the engine is running as already highlighted by Fast Fred in the previous thread. It could be expensive. On my boats I have always by-passed any switches with my charging wires to the batteries, with a splitter diode preventing any chance of one draining the other.

If your sole purpose in adding a second battery is for your trolling motor, then the selector switch is not what you need. All you need is the ACR between your batteries.

[Brylk1830]

I think you convinced me mack.. I have not bought anything yet but my local West Marine shop has both ACR and selector switches in stock. My motor does have a manual back up start so I guess i'll just calculate the total cost and see where i'm at. Thanks for all the help!

[murdomack]

If you have the manual start option, and you want to save money, you could place a simple on/off switch on the charging link between the batteries to get your system up and running, then buy the ACR when your funds are available.
Regarding the selector switches, I prefer the combiner off/on/combined switch that is shown in the West Marine wiring diagram to the selector off/1/both/2 switch.
I am going to see if I can improve my own system with one of them and an ACR. I could gain .25 Volt in my batteries maybe. Then again is it worth the trouble, I'm happy with what I get through the diodes?
Best of Luck.