Please help with DC wiring

Jeunesse27

Jeunesse27

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May 13, 2011
86
Catalina 30 Vancouver, BC
Thank you Bill, no hard feelings :) Your point on using just a switch to direct charging power has also been taken into consideration so don't think I was discarting it either :)
 
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Jeunesse27

Jeunesse27

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May 13, 2011
86
Catalina 30 Vancouver, BC
So I don't have a way to draw up a diagram at the moment, I will try to describe the way I'm going to wire things as accurately as possible see what you guys think. I know some of you wouldn't do it this way...

I currently have 4 batteries, 2 are older optima (one yellow top one blue top) and 2 are brand new blue tops. The reason I have optima batteries on board is because of my experience with them in cars. I now have learned that they are not the best choice for house banks as they are pretty low on the capacity (55ah each, they are D34M size)

What I want to do is use the yellow top as my start batterie, I will wire the positive terminal to the common side of a batterie switch, position one of the switch will go directly to starter. Alternator output will go directly to positive terminal of start battery. Now from position 2 of the motor battery switch will go to common lug of DC panel battery switch, position one of dc panel switch will go to the of of the other old blue top optima and position 2 of the dc panel switch will go to my 2 new blue top optima batteries. I will wire in one of the outputs from the xantrex to the positive of the old batterie which is on the DC panel switch (position 1) and another output from the charger to the new optimas which are wired in parallel on position 2 of the DC panel switch. The ACR will be wired between the start battery and the bank 1 house battery tying them together when either alternator is chagring or xantrex while leaving the new batteries isolated by the battery switch. Only way I will be able to charge the bank 2 (new optimas) is by physically putting the DC panel switch to position 2. I think this way I can monitor very closely when my old patteries pack it in and I can then upgrade to lifelines.

Any thoughts? possible flaws in my logic?
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,759
Canadian Sailcraft 36T Casco Bay, ME
Jeunesse27 said:
Very crude diagram but will have to do for now.
Click to expand
I am not quite sure why you have two 1/2/BOTH switches or what you are exactly trying to accomplish with them and it seems more of a short term band-aid..... Even with their differing age and your plan to upgrade I would simplify that system by losing one battery switch and putting a simple "on/off" in between the old and new house batts or just lose the old ones altogether.. If the yellow tops pack it in simple flip the on/off to off. Alternatively a third blue top may be the most simple measure to get the capacity you need. Those batteries work they are just light on capacity, which can be fixed by adding more. You have space for four so two more blue tops would be fine and make your system much less complicated.

it would also allow cross connecting the parallel string to keep them in balance significantly better than what the drawing shows.

My vote would be one or two more new blue tops, lose the second switch and keep it simple.

Also charging the start bank first, with dissimilar sized banks, can lead to relay cycling and is not a good practice...

Read this: http://forums.sbo.sailboatowners.com/showthread.php?t=137615
 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Hey Jeunesse
I developed a pretty thick skin while in the Army. Glad to see that there are no hard feelings.
Im with MS this could be simplified quite a bit. Looks like you actually have three battery banks. Is that a requirement for how you use the boat or just how it is wired now?
 
Jeunesse27

Jeunesse27

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May 13, 2011
86
Catalina 30 Vancouver, BC
I will answer all the questions as soon as I get home, in the meantime can someone tell me how to test a batterie? I know a battery is supposed to have about 12.7v standing voltage, but how do I test how many ah it actually still holds? I ask because I don't actually have a good idea if my older batteries are any good anymore or not. Why have them onboard if they have very little life left...
 
Jeunesse27

Jeunesse27

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May 13, 2011
86
Catalina 30 Vancouver, BC
Another question I came up with, I have been soldering all my connectors assuming it is a much more durable way of connecting wire to terminals. Am I correct in my logic? Would this be a good way of doing it if working with 4ga and larger wire as well? or is Crimping the preferred way?
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,352
Catalina 34 224 Maple Bay, BC, Canada
Jeunesse27 said:
Very crude diagram but will have to do for now.
Click to expand

WADR, did you read the links in Reply #27?

Don't bother soldering. Mechanical fastenings work just fine, crimp and use heat shrink.

Read Maine Sail's website.

G/L.
 
Jeunesse27

Jeunesse27

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May 13, 2011
86
Catalina 30 Vancouver, BC
I did read everything on the posted link. I'm just redrawing my diagram. Will post when I'm done.
 
Jeunesse27

Jeunesse27

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May 13, 2011
86
Catalina 30 Vancouver, BC
In this latest diagram I posted I have one questions (well probably many more, lol), how do I know when one of the batteries is dying? and by paralleling new and old batteries am I harming the new batteries? If so, any suggestions on altering the wiring? Now for the future, the reason I would rather go to Lifeline deep cycles is that they offer far more capacity per foot print. Ultimately I will end up with 2 GPL-27T, and either one Optima blue top D34M or a D31M
 
Jeunesse27

Jeunesse27

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May 13, 2011
86
Catalina 30 Vancouver, BC
I'm not interested in flooded lead batteries, don't want to deal with the fumes and ways of venting. Non spill fully sealed batteries is the way to go in y opinion, I'd go lithium iron phosphate batteries if I could afford it.
 
Jeunesse27

Jeunesse27

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May 13, 2011
86
Catalina 30 Vancouver, BC
MS you mention in the posted listed in the previous reply that you would choose to go with gel rather than agm, could you elaborate on why? Unless I missed it you didn't explain. Also according to what I read is that for me to take advantage of AGM's if I had a 200ah bank I'd have to have at least a 200A alternator/charger? (1C charge rate) and if they take a 5C charge I'd need 1000A??? I have quite a lot of experience with lithium polymer batteries coming from the R/C airplanes/helicopters world and our batteries take 5C charge rates. This has been hard to achieve up to recently even with 10cell 4000mah packs (42volts, 4amps).
 
Jeunesse27

Jeunesse27

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May 13, 2011
86
Catalina 30 Vancouver, BC
I will be checking to see what alternator I have, if memory serves me right it is a 90amp alternator.
 
Jeunesse27

Jeunesse27

.
May 13, 2011
86
Catalina 30 Vancouver, BC
Ok so more on AGM and xantrex... I wonder why does xantrex specify a minimum of 80ah banks per output charge post on a 40A charger??? My D34M battery can easily take 55A (1C) charge rate so it seems that me trying to satisfy xantrex specs by purchasing 2 D34M (55ah) batteries only works against me?! I should have had bought the 60A charger and only hooked up a single battery to it to take advantage of the AGM's fast recharge, as a matter of fact I could buy 2 60A chargers and wire them in parallel to charge my AGM's which is why I think they came out with the paralleling feature on the new TC2 models... I'm starting to get a really sour taste in my mouth from all the sales pitch BS from various stores and that includes Xantrex tech support...
 
M

mitiempo

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Sep 28, 2008
922
Canadian Sailcraft CS27 Victoria B.C.
Jeunesse27 said:
I'm not interested in flooded lead batteries, don't want to deal with the fumes and ways of venting. Non spill fully sealed batteries is the way to go in y opinion, I'd go lithium iron phosphate batteries if I could afford it.
Click to expand
If you want Agm batteries you should read this link I posted earlier. It describes in detail the care and feeding of Agm batteries if you expect them to last more than a year or two. It is by Maine Sail.
http://forums.sbo.sailboatowners.com/showthread.php?t=124973

It will answer most of your questions.
 
weinie

weinie

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Sep 6, 2010
1,297
Jeanneau 349 port washington, ny
I'd put the starter wire on the C post of the switch. And I'm not sure about mixing old and new batts in the same bank.
 
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