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Go Back   SailNet Community > On Board > Gear & Maintenance > Electrical Systems > Emergency battery charge ?
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Thread: Emergency battery charge ? Reply to Thread
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Topic Review (Newest First)
11-10-2010 10:57 AM
sterilecuckoo58 I am interested in this topic and especially how to add a solar panel... however that's another thread. Now, to SouthBrooklyn, this word from a newbie: Long Island is, well, long. Along the south shore are few harbors / inlets. But if the sky is clear, the shooting stars can be wonderful. We navigated twice at night, once in accordance with plan, and once to take advantage of lesser headwinds.
11-07-2010 10:15 PM
Stu Jackson
Quote:
Originally Posted by SouthBrooklyn View Post
Brian, would you agree that with the switch on "C" the fuses will blow when I start the engine? The idea, then, is to always use either 1 or 2, but not "Both". "Both" is used only during charging so both banks charge. 2 is just a reserve battery, to be used when 1 is out. Right?
Nope. Please think of how it works and which way the electrons flow.

The outboard is connected directly to the #1 bank. To start, the switch could be off. The battery powers the outboard to start and once started, that's it unless you have an alternator on the outboard in which case the electrons flow the other way and charges the #1 bank. The ACR parallels the banks.

The ONLY thing coming off the switch is the distribution panel, and the switch TAKES power from whichever battery bank you choose.

No need to use Both since the ACR does that automatically.

I'm going to go back to the last diagram and check it again.
11-07-2010 10:11 PM
Stu Jackson
Quote:
Originally Posted by SouthBrooklyn View Post
Brian, would you agree that with the switch on "C" the fuses will blow when I start the engine? The idea, then, is to always use either 1 or 2, but not "Both". "Both" is used only during charging so both banks charge. 2 is just a reserve battery, to be used when 1 is out. Right?
Nope. Please think of how it works and which way the electrons flow.

The outboard is connected directly to the house bank. To start, the switch could be off. The battery powers the outboard to start and once started, that's it unless you have an alternator on the outboard in which case the electrons flow the other way and charges the house bank. The ACr parallels the banks.

The ONLY thing coming off the switch is the distribution panel, and the switch TAKES power from whichever battery bank you choose.

No need to use Both since the ACR does that automatically.

I'm going to go back to the last diagram and check it again.
11-07-2010 09:33 PM
mitiempo They shouldn't blow under any normal circumstances with the correct fuse chosen. Size isn't real critical as you are fusing for a short circuit rather than overload. Fuse size can be up to 150% of the wire rating. I have fused start batteries without any problems.
Blue Seas ANL fuses are a good choice. The 150 amp ANL fuse will blow at 250 amps current at the 500 second mark. Your engine cranking should only last 15 or 20 seconds at the most.
Here's the link to circuit protection at Blue Seas. Short circuit fusing is described just below the chart.
Choosing Circuit Protection - Resources - Blue Sea Systems
11-07-2010 09:21 PM
SouthBrooklyn Brian, would you agree that with the switch on "C" the fuses will blow when I start the engine? The idea, then, is to always use either 1 or 2, but not "Both". "Both" is used only during charging so both banks charge. 2 is just a reserve battery, to be used when 1 is out. Right?
11-03-2010 08:53 PM
mitiempo The single output is a better choice, regardless of the opinion of the Guest tech. With an ACR the dual defeats the purpose.

Fuse sizing is not critical. You are fusing for short circuit, not overload. Here's the link that explains it well. See short circuit protection just below the chart.
Choosing Circuit Protection - Resources - Blue Sea Systems

Here's an explanation of fusing batteries Blue Seas re ABYC E-11

In the diagram you posted notice the fuses after the switch. The source of any problem will be the batteries. If they are fused close (within 7") the possible problem is solved at the source.
11-03-2010 08:33 PM
SouthBrooklyn Brian, the tech at Guest said both will work, but he would go with the dual. I will get the single, it has more safety features, has a fuse already and there are two less wires to deal with.

I will also get the double terminal blocks (attached image) with 75A fuses for the ACR wires and 125A fuses for the switch wires. I am not sure if these are the right sizes, I've been reading all kinds of articles and documentation, my head is as big as a battery now, and I feel I need a fuse myself.

Also, what's up with the ABYC diagram? It says that wires between the battery and the switch do not require a fuse.

Best.
11-03-2010 03:29 PM
mitiempo ABYC calls for a fuse on the battery positive within 7" of the post. The breaker panel you have wired to the common on the switch will protect the wires after the breakers but not before. The exception is if the battery is a dedicated start battery, but I fuse them as well. If a battery came loose in rough weather or was shorted by something you want the fuse to go. The fuse I pictured is the easiest way and saves on cables. They are also available with 2 studs and fuse holders.
The ACR could(should) be fused and just like fusing a start battery it depends what fuse you use. I have never had a problem with fuses on start batteries for diesels. The Blue Seas ANL fuses will withstand about 150% of their rating for 500 seconds.
Surprised they recommended the dual charger with an ACR connecting the banks.
11-03-2010 02:35 PM
SouthBrooklyn OK, this is the latest and I'm not going to bother you anymore. If I don't have to.

I spoke with the charger manufacturer and they recommended I get the dual charger.

I also spoke with the ACR manufacturer and they said that the diagram works with the unit. They said that there is no need for a fuse on the outboard wire, because it will surely blow.

Somebody also mentioned that, since from C on the switch the wire only goes to a panel with circuit breakers, I don't really need fuses between the batteries and the switch. If they are needed, then I'll get a positive distribution post, as per Stu.


Thank you.
11-03-2010 12:24 PM
Stu Jackson Brian's suggestion for the fuse at the bank is a good one if you've only got ONE wire to fuse. Instead, consider a Blue Seas Power Post, which is pretty much what it says: a post to gather the wires and their fuses and then run a single short wire to the house bank positive. BLUE SEA SYSTEMS Power Post Single Terminal Connectors at West Marine

If you do this, it's then called a PDP, positive distribution post. Do the same for the negatives (NDP) or use a bus bar for them, too. It avoids loading up the posts on the batteries. Reason is the weight of all those wires can strain the battery post.

Renumber the batteries to avoid confusion with the 1 & 2 on the switch. House bank 1 and 1A or 1A and 1B, reserve bank 2.
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