What is this in my engine compartment

Siamesekat

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Mar 12, 2013
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Picked up my boat today and took a few more pics. Found this behind the jump seat with the battery. What's it's purpose in life? Looks like a heatsink but.. And the silver thing under it. Have a thought but.
 

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Don S

Honorary Moderator Emeritus
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62,321
Re: What is this in my engine compartment

Looks like a battery isolator (heat sink looking thing) and the silver thing is a solenoid. All mounted on a board. Not Oem for sure, and who knows where all the wires go.

If you can make a drawing of where all the wires go from each terminal of both items, I'm sure we can figure out what has been done
 

Siamesekat

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Mar 12, 2013
Messages
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Re: What is this in my engine compartment

Will trace what I can after I get it home next weekend. Wonder what they were thinking when they mounted it like that. Ahh well. Hoping to get the boat wet soon and see how she does.
 

Greg_E

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Feb 17, 2009
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Re: What is this in my engine compartment

Yes it looks like a homemade battery isolator / combiner. West Marine sells or used to sell something similar. I think the purpose of the solenoid was to disconnect the two batteries when the ignition is off. Both battery are charged when the engine is running, and disconnected from each other when it's off. The isolator has reverse current leakage, so if you had one bad battery, it can still draw down the good one over time. The solenoid keeps that from happening. I'm not sure I have that 100% correct. It's been a long time since I've seen or used one.
 

Siamesekat

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Joined
Mar 12, 2013
Messages
12
Re: What is this in my engine compartment

Yes it looks like a homemade battery isolator / combiner. West Marine sells or used to sell something similar. I think the purpose of the solenoid was to disconnect the two batteries when the ignition is off. Both battery are charged when the engine is running, and disconnected from each other when it's off. The isolator has reverse current leakage, so if you had one bad battery, it can still draw down the good one over time. The solenoid keeps that from happening. I'm not sure I have that 100% correct. It's been a long time since I've seen or used one.



I still have to trace it out but there is only one battery in it. Has a battery cover under the jump seat but the actual placement is behind the seat. No shut-off switch either so it's live all the time.
 
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