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Another 12v/24v question

Old 04-26-2004, 06:18 PM
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Default Another 12v/24v question

Sorry if I’m still beating this old dead horse. I have a 12v/24v question(s) and just want to get some others comments on this.

Some information on my installation:

Boat has twin HPDI’s
Motors each have two charging leads and a built-in isolator.
I need 24v power to run a Furuno radar.
I need the ability to keep my two house batteries separate for 24v power, but I need to be able to charge both batteries with only one motor running.
I need the security of having multiple batteries for starting or running 12v electronics.
I want to keep everything as SIMPLE as possible…the fewer the connections the better.

I guess I want comments on 1) makes sense? 2) won’t blow anything up? 3) lastly, where to place my battery switches?

Thanks in advance for any help!

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Old 04-26-2004, 08:21 PM
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Default RE: Another 12v/24v question

How does the "24V battery" the one on the top of the series combination get its ground referenced to the alternator of the engine?
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Old 04-27-2004, 08:06 AM
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Default RE: Another 12v/24v question

I 'think' the batteries would all use the 12v ground (which I need to add to my diagram). The 24v ground is then created when the two are placed in the series.
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Old 04-27-2004, 08:47 AM
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Default RE: Another 12v/24v question

I dont think the left engine will be able to charge the top battery. It's only going to put out ~14 volts referenced to it's ground. The top battery is floating on 12 volts already. So for the top battery to get charged up it would need the alternator of the left engine to put out ~14 volts floating on top of the 12 volts of the bottom battery.

The problem with floating the ground of the left engine on the bottom battery +12v, is corrosion. You would get electrolosis currents flowing in the water between the 2 engines due to their difference in ground potentials, and soon dissolve them in salt water.


And the top battery can not tie it's - post to the same ground as the bottom battery, cause that would short out the bottom battery. that would be bad too.
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Old 04-27-2004, 09:27 AM
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Default RE: Another 12v/24v question

sea_dad, you bring up a great point and one that I did not think of. The boat is keep out of the water so it would take a long time for the engines to disolve. But regardless I don't want to have it setup incorrectly.

Honestly I think I'm trying to do something that just can't be done?? I'm only going to be able to charge the house batteries off of one of the motors and not either/or.

Off the FS forum I was recommend to look at this: http://www.dualpro.com/xtreme_series.htm

Seems that this can charge my batteries either from the engines 12v source or via shore power...which at times could be nice. It charges them all as individual batteries.

Thinking out loud...could I do what I'm wanting by adding a switch that I could switch to the corosponding 'running' engine (a switch for both the pos and neg)? Does that make sense and is that a viable way?
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Old 04-27-2004, 09:30 AM
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Default RE: Another 12v/24v question

hmmm maybe feeding the dualpro with a combiner is the ticket. That way no matter which engine is running the dualpro would get power.

It would certainly simplfy it for you.

Maybe go to their web page and see if they have installation examples. I would check that the outputs float so you can charge the top batt, regardless of the power source.
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Old 04-27-2004, 09:32 AM
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Default RE: Another 12v/24v question

What about my ground? I don't want my motor to disolve!!
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Old 04-27-2004, 09:34 AM
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Default RE: Another 12v/24v question

swap the isolater with a combiner, and then put the dualpro inbetween the combiners output and the 2 batteries. Then the ground situation is moot.



by the way, with 12 volt difference between the 2 engines grounds, and assuming the engines can charge at 20 amps or better, you would do damage to them in a single day. You can anodize parts with that potential.
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Old 04-27-2004, 09:37 AM
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Default RE: Another 12v/24v question

Ummm a combiner. I need to read up on those...not sure what they do differently??
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Old 04-27-2004, 09:41 AM
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Default RE: Another 12v/24v question

they take the 2 alternator inputs, and output a single +12V. It's just a couple of diodes with the cathodes tied together. just look up combiner/isolaters. it's the cousin of the isolater you drew originally.
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Old 04-27-2004, 10:21 AM
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Default RE: Another 12v/24v question

Buck Wild,

Sorry, but this whole project sounds a little like the 6 Pollacks trying to screw in a light bulb. Is there some reason why you don't want to convert the radar to 12v with a 12v to 24v convertor? No battery, no charging, pretty straightforward. The convertor is a standard aviation product.

SN
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Old 04-27-2004, 10:28 AM
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Default RE: Another 12v/24v question

cabosn, can you supply a source for one that is ruggedized, corrosion resistant, and not real expensive?
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Old 04-27-2004, 10:49 AM
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Default RE: Another 12v/24v question

buck, check the diagram in this thread.

http://thehulltruth.net/forums/threa...osts=16#M83984
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Old 04-27-2004, 11:09 AM
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Default RE: Another 12v/24v question

That is a great diagram...I actually printed it and saved it awhile back. I can use this and it will help...my issue is that I will have four banks instead of three.
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Old 04-27-2004, 11:10 AM
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Default RE: Another 12v/24v question

cabosn, what product do you recommend?
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Old 04-27-2004, 11:54 AM
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Default RE: Another 12v/24v question

I think I saw on the web that guest sells a 2 alt / 4 battery charger. I would imagine it can also plug in at the house as well.
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Old 04-27-2004, 12:26 PM
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Default RE: Another 12v/24v question

Where did you find that??? Sounds like that is what I'm after, but I can't find it and when I go to download Guest's catalog my system hangs up.
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Old 04-27-2004, 12:50 PM
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Default RE: Another 12v/24v question

I believe it was boaters world. or maybe west marine. but they both carry them.
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Old 04-27-2004, 03:16 PM
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Default RE: Another 12v/24v question

Buck Wild

How many amps is your radar?

SN
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Old 04-27-2004, 06:46 PM
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Default RE: Another 12v/24v question

Buck Wild

You might try the below link for a 12 to 24 volt converter. Have no idea of the price, but they appear to be good quality.

http://www.analyticsystems.com/converters.htm
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