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Dual Battery System

phare's Avatar
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08-23-04, 10:53 AM   #1  
Dual Battery System

Hello, I have recently installed a simple switch over system on my boat. The charge from the alternator is simply directed to either battery depending on a switch at the control panel that switches a heavy duty relay in the engine compartment. I would like to be able to have an ammeter at the control panel which tells me how much charge the battery is taking while under way and how much juice I am using while stationary. I understand that the ammeter must be in series and I understand where it needs to go in the circuit. The question I would like help with is how do I run a feed to the ammeter without carrying all the current up to the control panel. Apparently a shunt is what I need, though I don't know how this works with a standard 12v ammeter. Any advice would be appreciated.

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Ed Imeduc's Avatar

Join Date: Aug 2002
Posts: 18,389

08-24-04, 02:19 PM   #2  
Not sure what you have there. But on 2 battery set up we run the charge to both Batts with a digital duo charger. that way both get charged and we can use what one we want for engine or boat. Check out www,defender.com they have them.


BoatMech's Avatar

Join Date: Dec 1999
Posts: 592

08-24-04, 07:53 PM   #3  
That shunted style system died out in the seventies with generators.
and i doubt if you can find the proper gauge to work with it.
i am not disapprooving of it, i just feel there is a more economical and
safe way to direct your charging current and read its flow.
first, if you split the connection from the battery to the alt. underway
you risk damaging the diodes in it.
lets install a battery isolator
that takes the amperage and diverts it to as many as three banks
of batteries.
you can pull your accy line up to the dash and use an ammeter to
monitor you usage and lets use a voltmeter to monitor charge rate.
ok. thanks

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