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Old 26-06-2017, 08:48   #1
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What size cables in large house bank

Rewiring my house bank and have a question about the size cables to use.

Setup is six batteries, 6V each wired series/parallel. The cables to link the six individual batteries are only 7" long. Since it's the house bank 90% of the time I'll be drawing no more that 5-10-15 amps but do have a 2000 W inverter attached and have the system wired so if needed could use the house bank to start the engine. Either of these could draw up to 150-200 amps at 12 V from the batteries.

According to tables and calculations for voltage drop and cable capacity, a 1 gauge wire would safely carry over 200 amps and drop less that 0.1V for 7"
or even for 21" if you add the drop for all the connectors. However, this doesn't take into account the distance from the battery bank to the starter or inverter.

So the question, will using a 1 gauge cable for linking the batteries be a problem? Yes I know I could use larger but the smaller cables are much more flexible and will be much easier to bend to the shape I need to fit the setup.

I will use 0 or 00 for the longer cables to the starter and the inverter.
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Old 26-06-2017, 23:12   #2
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Re: What size cables in large house bank

None of the jumpers will carry 200a. Ie the 3 series cables will carry 1/3 each. The parallel cables will carry 1/3 and 2/3. Depending on which end of the bank you pull power from. That said. I normally make all the jumpers the same size as the cable leaving. Ie 2/0. Easier to carry one spool and bag of same size lugs. 2/0 jumpers bend and work fine.

1awg is not common at all. And I get pissed when I see it. Because I don't carry lugs for it. Same for 3/0. Both super rare on boats
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Old 29-06-2017, 06:56   #3
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Re: What size cables in large house bank

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Originally Posted by smac999 View Post
... Ie 2/0. Easier to carry one spool and bag of same size lugs. 2/0 jumpers bend and work fine.

1awg is not common at all. And I get pissed when I see it. Because I don't carry lugs for it. Same for 3/0. Both super rare on boats
Good to know that even gauges are uncommon. I picked 2/0 for the house battery cabling in the battery photo in my previous thread.

Does anybody go to 4/0 for battery cabling and/or starter motor cabling?


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Old 29-06-2017, 08:41   #4
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Re: What size cables in large house bank

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Originally Posted by ayates View Post
Good to know that even gauges are uncommon. I picked 2/0 for the house battery cabling in the battery photo in my previous thread.

Does anybody go to 4/0 for battery cabling and/or starter motor cabling?


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I have used plenty of 4/0 on big diesel sportfish and motor yachts. Can't think of a sailboat i have used it on.
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Old 30-06-2017, 22:07   #5
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Re: What size cables in large house bank

3 american wire gauge will be fine for what you described
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Old 01-07-2017, 14:52   #6
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Re: What size cables in large house bank

In the OP's case I would suggest 2/0 for everything, assuming the inverter is reasonably close to the batteries. After the install is finished you are very unlikely to wish you used smaller cable, but if you have voltage drop issues, wishing you'd gone one size larger would be frustrating.

If you are wiring the inverter separately from the start circuit and dc panel, you may choose to go with a smaller cable to the dc panel. Remember to size it for 3% voltage drop or better.
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