2 engines - 2 batteries to be charged

bartonstreet

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Aug 28, 2011
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I've got a 3.0L OMC and a 15hp kicker Merc. on my old Islander.

I'm setting up a "house" & "starting" batteries arrangement with a Blue Sea "Add-a-Battery" ACR & switch system. What I need to know is whether I can simply parallel the charging outputs of both engines (so they would look like one source of charge to the rest of the boat after the battery switch)? Or, do I need to add another switch so as to select which engine will be doing the charging? I don't think I would ever need to run both engine at the same time.

I'll be trolling for walleye (often at night), and I want to make use of the 10amps available from the kicker. I'll be using the start isolation feature of the ACR.

Would the regulator (or anything else) on the shut down engine be damaged by the output of the running engine? It seems that there'd be no problem.

TIA
****
 

fucawi

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May 18, 2011
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Re: 2 engines - 2 batteries to be charged

provided you are not running the two engines at the same time you can connect the outputs.
Make sure your little kicker has a nominal 12v ( not 6v ) DC output ..many come without the rectifier ..cheap from Radio Shack ..as they are intended for running lights which are happy on AC.
Even with both engines running your only problem could be the higher unregulated kicker could cause the larger engines regulator to shut down its output...but I dont see any damage.
 

Don S

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Aug 31, 2004
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Re: 2 engines - 2 batteries to be charged

Hook your kicker directly to the house battery, not the main engine starting battery. The charging system on a 6 hp is so small, it will just keep up with the running lights and possibly the depth sounder.
Will not hurt either charging system if you did run both at the same time.
 

bartonstreet

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Aug 28, 2011
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Re: 2 engines - 2 batteries to be charged

Even with both engines running your only problem could be the higher unregulated kicker could cause the larger engines regulator to shut down its output...

Since the O/B (2005 Merc 4stroke) was operating with it's own battery originally, I'll assume it's output was regulated properly.

Hook your kicker directly to the house battery, not the main engine starting battery. The charging system on a 6 hp is so small, it will just keep up with the running lights and possibly the depth sounder.
Will not hurt either charging system if you did run both at the same time.

My Merc O/B is a 15hp electric start that is spec'd as 10 amps out. I figure that should easily handle the load while trolling. The original owner had the O/B on it's own 12v marine battery, and he had a set of (cheap) jumper cables to combine the batteries if needed. Yankee ingenuity! The boat as a whole was mostly the original one-battery factory wiring.

Thanks for setting me straight, guys. You give me good news! Now I can make out my wiring shopping list.
 
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