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Old 10-19-2011, 08:51 PM   #1
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1964 26' Overlander
Richmond , Virginia
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Question How long can my battery cable be - and what gauge wire?

I have a 64 Overlander that had the battery in the rear compartment. I was able to snag a new huge UB4D 200AH battery for $100 at a local freight salvage place near me (been watching for one all summer)

Now that I have it, I want to balance out my fresh water that is on the driver's side wheel well by putting this new AGM under the bunk on the passenger side. It's roughly 14 feet if I snake the wire around the tub, through the old battery compartment, and back to the new 45amp progressive dynamics I got from VTS.

So, can I run the wire that far, and what gauge? Also, do I need an inline fuse for that?

Finally, I just used a pair of car jumper cables to connect it to the inverter for now to keep the charge on. I did notice that when I unplugged the power the lights dim about 5%. It's not bolted on like it will be in the future - I had almost all the lights in the AS on at the time. Are they normally a little less bright when running on DC?

Thanks folks!

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Old 10-19-2011, 09:30 PM   #2
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1973 27' Overlander
1972 29' Ambassador
St. Paul , Minnesota
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Talk about a neat score!

Yes - loads, especially lights, will noticeably dim on DC alone, your battery produces 12.7VDC but is charged by 13.5-14.2VDC so loads with AC 'help' grab the cream off the top so to speak.

30 amps over 15-feet of 8AWG (one-way measure but round-trip) will drop 5%, 6AWG will drop 3%. The flexible, fine stranded type cable with crimped lugs is what you want. HERE is a link to an online wire-size calculator.

Running the battery primaries through a doomsday fuse or circuit breaker near the battery is a good thing. If you find a C/B it also makes a good isolation switch but they don't like to be exercised multiple times daily day in and day out...


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Old 10-20-2011, 05:49 AM   #3
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1965 22' Safari
Vassar , Michigan
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robwok - I did the same thing you are doing with my 65 Safari. I removed the trunk bat. & installed 3 group 27 100AH Lifelines under the goucho infront of the the axle. I used 4 gauge multi-stranded, heavy duty, flexible wire that is color coded. Got it from a car audio shop. It's a bit pricey but easy to work with being so flexible. Mine is about a 13' run. Take a look at this site: Stinger SHW14B HPM Car Audio 4 Ga Blue 1400W Power Wire - 1 Ft. Per Order - SHW14B

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Old 10-20-2011, 09:52 AM   #4
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1964 26' Overlander
Richmond , Virginia
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Thanks guys, that's really helpful.

I have another thought. I replaced the cord from my original univolt and installed a furrion hookup outside the trailer, and bought a new cord for that.

Is the wire in the original black heavy extension cord big enough for this job? Any recommendations against it? The cord has been stored out of the sun for the last 50 years, but not sure about the gauge.

It seems like battery cable cords have to be thicker than household cords. It's the finer points of electrical work that get me. I can wire a panel, and run new circuits through my house, but the Airstream has been a huge learning curve for me. I needed to save a little space in the 45amp all in one unit, so I used solid wire since the stranded was so much bigger( although solid is a real pain to bend correctly) Anyway, should i go with new wire, or is this of the very few items I can recycle?
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battery, cable, connection, power, 12v

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