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  #11  
Old 11-16-2018, 03:40 PM
Red45 Red45 is online now
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Why is leaving the switch on so the charger connected to one battery charges both not suggested? That's how I've been doing it. Can this cause problems?
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  #12  
Old 11-16-2018, 03:49 PM
lj_mastercraft lj_mastercraft is offline
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I don't like the idea of leaving power on to all the boat's electronics (audio, etc).
I have everything wired through the perko, including the bilge pumps.

I just know that with my luck, leaving the switch on will come back to bite me one day.

Also the device I have (or would get) would be primarily a maintainer. The batteries seldom need to actually be charged much.
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  #13  
Old 11-16-2018, 03:50 PM
MLA MLA is offline
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Leaving the main switch, leaves the boat powered up. Any parasitic draws can keep the charger out if its float/idle mode. This is rough on a charger and batteries.
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  #14  
Old 11-16-2018, 04:00 PM
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Thanks guys. Another maintainer on order today just to be safe. I'll hang one on each battery and switch the boat off. $10 for another maintainer is better than $150 for a new battery.
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  #15  
Old 11-16-2018, 04:33 PM
88 PS190 88 PS190 is offline
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So in the second example you pretty clearly have two 12v batteries wired in parallel which the charger will see sort of an average of the two batteries, and also the two batteries are no longer isolated from each other because power can go from the disconnected battery back up to where it spliced together at the charger and then back to the battery with the draw. So in application id you hardwire it that way you'll draw power from both to the radio etc.

First example is good.
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  #16  
Old 11-17-2018, 10:56 AM
lj_mastercraft lj_mastercraft is offline
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Quote:
Originally Posted by 88 PS190 View Post
So in the second example you pretty clearly have two 12v batteries wired in parallel which the charger will see sort of an average of the two batteries, and also the two batteries are no longer isolated from each other because power can go from the disconnected battery back up to where it spliced together at the charger and then back to the battery with the draw. So in application id you hardwire it that way you'll draw power from both to the radio etc.

First example is good.
It's true in the second example I have them both wired up in parallel, and the idea there would be that the charger would see the total load of both batteries. I didn't know it would be a problem for the batteries to be isolated from each other, but I did want to keep them isolated from the boat's electronics.

I disagree that the radio (or any of the boat's electronics for that matter) would come into the picture in either of the two drawings - the Perko would still be 'off', isolating them
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  #17  
Old 11-17-2018, 12:18 PM
MLA MLA is offline
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I disagree that the radio (or any of the boat's electronics for that matter) would come into the picture in either of the two drawings - the Perko would still be 'off', isolating them
OFF, yes. But in 1 or 2, your batteries are technically in parallel through a wire thats 14ga at best. So drawing down one, bank, the other will want to equalize into it through your charger Y splice. Hopefully you have a fuse on each B+ charge lead right at the battery.

So not an ideal setup from any angle.
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  #18  
Old 11-19-2018, 03:31 PM
lj_mastercraft lj_mastercraft is offline
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Quote:
Originally Posted by MLA View Post
OFF, yes. But in 1 or 2, your batteries are technically in parallel through a wire thats 14ga at best. So drawing down one, bank, the other will want to equalize into it through your charger Y splice. Hopefully you have a fuse on each B+ charge lead right at the battery.

So not an ideal setup from any angle.
I don't understand how they are in parallel when 1 or 2 is selected? Only time they would be in parallel would be when in "ALL" right?

Moot point as the switch would be in OFF, but i'm still curious. If they were in any way parallel in 1 or 2, then that would defeat the switch's purpose
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  #19  
Old 11-19-2018, 04:16 PM
88 PS190 88 PS190 is offline
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Go back to your second photo:

The blue Arch is the same as the Blue Line - you've connected the two positive sides of the batteries together through the charger's wire by splicing them together.

So switch in 1 has a heavy battery cable to battery 1, then a light wire to the splice and back to the other battery. In 2 its the same, heavy wire to battery 2 light back to battery one through the splice.

In off neither is connected to the engine but both are connected together by that same splice.

Which means say battery #1 dies, its going to draw battery#2 down via that splice.

Or worse case scenario, lets say you are just cranking cranking cranking and you draw down battery 1 alot - as battery 1 gets low more voltage difference will exist between battery 1 and battery 2 until it melts that wire unless both legs are fused.
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  #20  
Old 11-19-2018, 04:22 PM
88 PS190 88 PS190 is offline
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You actually could wire some Diodes in there giving the direction of + flow only towards the battery in each leg....
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