Connect alternator outputs of two motors to battery bank

ironring1

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I have a Mercury 2-stroke 50HP outboard and a honda 4-stroke 8HP outboard on my boat. Do I need ti take any precautions before connecting the Honda's 12V output to my batteries so that it can charge them too?

That is, do I need to do anything special when connecting two different alternator outputs to a common battery bank?
 

cyclops222

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Alternators do not care a bit if they are connected to a 2 or a 4 stroke motor.
Normally ...ONLY...1 alternator recharges the batteries. Do not connect 2 alternators together in any way at any time.
 

tpenfield

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Might be a stator (on the small OB) vs. an alternator on the larger OB. It would be best to have a battery isolator in between.
 

ironring1

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Alternators do not care a bit if they are connected to a 2 or a 4 stroke motor.
Normally ...ONLY...1 alternator recharges the batteries. Do not connect 2 alternators together in any way at any time.
Thanks. This was my thought, too. I've left the small motor's 12V output disconnected until I sort this all out. Of course, I want to be able to charge my batteries while the large engine is off, so I'll need to sort out what extra hardware I need to combine the two charging sources.

I realize the alternators don't really care what kind of engine is spinning them - I just included that info for additional context.
 

Jeff J

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I think I would run them through a switch and select which alternator I wanted to be charging.
 

alldodge

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Might be a stator (on the small OB) vs. an alternator on the larger OB. It would be best to have a battery isolator in between.
I do like the isolator
But I'm thinking about the sense lead connection. The ALT needs to be able to read the voltage at the BAT so not to over or under charge. A Bat switch could be used but would need to switch

Without looking close at both Apps I'll assume neither puts out much in the way of Amps. The motors most likely can barely have enough more than just to keep the Bat charged. Could probably use a lawn mower Bat for the 8hp
 
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