I am sorry I started this project as it still is keeping me up at nights. As part of adding my refrigeration I am adding 4 AGM batteries, however looking at my existing acid batteries I find the positive wire is 4 gauge and the negative a 1/0. What is the reason for the difference? Any help is greatly appreciated!
Thank you.
Charlie Mauk
s/v LadyBug #138
svladybug@msn.com
CD36 Battery Cables........nightmare project
Moderator: Jim Walsh
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Patrick Turner
Re: CD36 Battery Cables........nightmare project
Charlie,
I don't think there is a good reason for having different gauge wire on your battery terminals. I redid my batteries, etc. last year on my CD36 and used 1/0 on everything (batt terminals that is). I currently have just 2 group 31's, but plan on doubleing that this year. I have 1/0 wire that leads from the batts to pos and neg distribution bars and from there to various chargers/alternators/panels/etc.
Pat
patrick.t@home.com
I don't think there is a good reason for having different gauge wire on your battery terminals. I redid my batteries, etc. last year on my CD36 and used 1/0 on everything (batt terminals that is). I currently have just 2 group 31's, but plan on doubleing that this year. I have 1/0 wire that leads from the batts to pos and neg distribution bars and from there to various chargers/alternators/panels/etc.
Pat
patrick.t@home.com
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John R.
Re: CD36 Battery Cables........nightmare project
As Pat says there is no reason for the difference. Both should be the same. The AWG gauge depends on the total circuit length x amperage. Consult a 12V wiring chart to determine the appropriate gauge for your situation.Charlie wrote: I am sorry I started this project as it still is keeping me up at nights. As part of adding my refrigeration I am adding 4 AGM batteries, however looking at my existing acid batteries I find the positive wire is 4 gauge and the negative a 1/0. What is the reason for the difference? Any help is greatly appreciated!
Thank you.
Charlie Mauk
s/v LadyBug #138
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Joe Mac Phee
Re: CD36 Battery Cables........nightmare project
Charlie,
The asymmetry between your cables may be related to how the wiring is configured. I have seen some installations where the negative returns are wired in series from battery to battery (daisy chained). In this arrangement, all of the current from all of the batteries goes through the one series cable. In some installations, it is also possible that the negative return is significantly longer than the positive. Negative usually goes to some common point (perhaps distant) and the positives to a battery switch or combiner.
I rewired my batteries last year using 1/0 throughout, and it made a significant difference in engine starting. After crimping the terminals, I used heat shrink tubing with internal adhesive to hermetically seal the connections.
If you require consulting or just tea and sympathy during this ordeal, contact me off list.
Happy wiring,
Joe Mac Phee
S/V Iolanthe
CD-30 K
jvmacphee@aol.com
The asymmetry between your cables may be related to how the wiring is configured. I have seen some installations where the negative returns are wired in series from battery to battery (daisy chained). In this arrangement, all of the current from all of the batteries goes through the one series cable. In some installations, it is also possible that the negative return is significantly longer than the positive. Negative usually goes to some common point (perhaps distant) and the positives to a battery switch or combiner.
I rewired my batteries last year using 1/0 throughout, and it made a significant difference in engine starting. After crimping the terminals, I used heat shrink tubing with internal adhesive to hermetically seal the connections.
If you require consulting or just tea and sympathy during this ordeal, contact me off list.
Happy wiring,
Joe Mac Phee
S/V Iolanthe
CD-30 K
jvmacphee@aol.com
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Larry DeMers
Re: CD36 Battery Cables........nightmare project
Charlie,
The dual sizes on the battery are bad news. It means that the maximum circulating current in the DC system is being controlled (limited) by the AWG4 wiring, making the 1/0 wire an expensive piece of ballast! They should both be 1/0.
I did a complete rewiring,repaneling (electrical panel) of my CD30 last summer, in preparation for the refrigeration project this summer, so know of your nightmare..although I would not say that ours was a nightmare..just a long project. If you have probems or would like another opinion from an E.E., please contact me at demers@sgi.com. I would be glad to help where possible.
Best of Luck,
Larry DeMers
s/v DeLaMer
Cape Dory 30
demers@sgi.com
The dual sizes on the battery are bad news. It means that the maximum circulating current in the DC system is being controlled (limited) by the AWG4 wiring, making the 1/0 wire an expensive piece of ballast! They should both be 1/0.
I did a complete rewiring,repaneling (electrical panel) of my CD30 last summer, in preparation for the refrigeration project this summer, so know of your nightmare..although I would not say that ours was a nightmare..just a long project. If you have probems or would like another opinion from an E.E., please contact me at demers@sgi.com. I would be glad to help where possible.
Best of Luck,
Larry DeMers
s/v DeLaMer
Cape Dory 30
Charlie wrote: I am sorry I started this project as it still is keeping me up at nights. As part of adding my refrigeration I am adding 4 AGM batteries, however looking at my existing acid batteries I find the positive wire is 4 gauge and the negative a 1/0. What is the reason for the difference? Any help is greatly appreciated!
Thank you.
Charlie Mauk
s/v LadyBug #138
demers@sgi.com
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Mark Yashinsky
Take your time
As was asked earlier, what is the current layout, a common ground, daisy chaining all the negatives, and individual positives going to battery selector(s) switch or battery combiners??? Think of the load on each of the cables, the length, and where they run (temp). There are plenty of spots that give cable size/cable length/amps allowed. How are you charging this setup??? Dont forget charging current (after running the batteries down)! Also watch where cables snake thru any tight areas. You might find that larger sizes JUST DONT FIT. Rewired Goldsmith's CD27, Second Chance, during last winter's haulout, and found that #1 cable will NOT fit inbetween the various bulkheads to the battery switch. Had to use #2, which is still an upgrade from the #4 originally there. All the original primary (battery, starting, charging) was removed. Generally, to prevent stray currents from floating around the boat, all the grounds usually tie to one spot, i.e. the engine/transmission case. Probably find one #1/0 from the batteries to the engine block and all returns going to that point. Also, its not a nightmare project, just take your time and think it thru.
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Ken Coit
Re: CD36 Battery Cables........nightmare project
Charlie,
If you have multiple batteries or banks using a single ground return, then there is certainly a chance that you need a larger ground return than the positive leads. For example, if your multiple bank charger can charge three banks at 20 Amps each, then either you have three complete circuits that will handle the 20 Amps or, when they are all active, you have three positive leads handling 20 Amps each and one ground lead handling 60 Amps. Thus, for the negative return to have the same drop and margin of safety as the positive leads, you need three times the cross-sectional area. However, balancing the loss on postive and negative leads isn't nearly so important as keeping the load to the capacity of the cabling. If you only use or charge one bank at a time, then you can size your wiring to the maximum current (amperage) to/from a single bank.
My new charger will charge three banks. It has three positive connections and one larger negative connection. I have used heavier cable on the negative side.
I know you are racing the weather window to head south, but be patient, enjoy the cool weather, and good luck!
Ken
CD/36 Parfait
Raleigh, NC
parfait@nc.rr.com
If you have multiple batteries or banks using a single ground return, then there is certainly a chance that you need a larger ground return than the positive leads. For example, if your multiple bank charger can charge three banks at 20 Amps each, then either you have three complete circuits that will handle the 20 Amps or, when they are all active, you have three positive leads handling 20 Amps each and one ground lead handling 60 Amps. Thus, for the negative return to have the same drop and margin of safety as the positive leads, you need three times the cross-sectional area. However, balancing the loss on postive and negative leads isn't nearly so important as keeping the load to the capacity of the cabling. If you only use or charge one bank at a time, then you can size your wiring to the maximum current (amperage) to/from a single bank.
My new charger will charge three banks. It has three positive connections and one larger negative connection. I have used heavier cable on the negative side.
I know you are racing the weather window to head south, but be patient, enjoy the cool weather, and good luck!
Ken
CD/36 Parfait
Raleigh, NC
Charlie wrote: I am sorry I started this project as it still is keeping me up at nights. As part of adding my refrigeration I am adding 4 AGM batteries, however looking at my existing acid batteries I find the positive wire is 4 gauge and the negative a 1/0. What is the reason for the difference? Any help is greatly appreciated!
Thank you.
Charlie Mauk
s/v LadyBug #138
parfait@nc.rr.com