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What ga wire do I need ?

dockmasterdave
Explorer
Explorer
I currently have a WFCO 45 amp converter. I have never been happy with it.
I have a voltmeter that tells me it is almost always at 13.6 volts. It never drops below that and in 8 years I have only seen it hit 14.4 once. I e mailed Randy at best converter a while back, and he suggested replacing it with a PD 55 amp wildkat. I bought that one and it came yesterday.
The instructions say " DO NOT " replace a converter with a higher amperage one.
I was hoping that the factory might have used a heavier wire than necessary, just to simplify their stock by using the same wire they have for a larger unit.
I checked my wires and they clearly say 6 AWG.
Does anyone know if #6 AWG is sufficient to handle 55 amps to a 2 battery bank at 20' ?
Thanks for any input. If I needed to run heavier wire, I can get at everything to do that. I just figured there must be a formula for amperage at a certain distance and wire gauge, and if any would know, it would be someone on here.
2014 F 150 ecoboost
2008 Chrysler Aspen
09 Amerilite 21 (modified)
2013 Bendron 14' enclosed cargo
2011 4x8 open cargo
15 REPLIES 15

2112
Explorer II
Explorer II
I have to ask, what is the total Ah of the batteries you wanting to charge? Do most typical battery banks demand more than 30A charge when depleted? And if it does, how long will the current be above 30A? Mods may not be needed.
2011 Ford F-150 EcoBoost SuperCab Max Tow, 2084# Payload, 11,300# Tow,
Timbrens
2013 KZ Durango 2857

time2roll
Nomad
Nomad

CA_Traveler
Explorer III
Explorer III
I love it when a plan comes together!
2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
750 Watts Solar Morningstar MPPT 60 Controller
2014 Grand Cherokee Overland

Bob

dockmasterdave
Explorer
Explorer
Update
I looked online and found a 60 amp surface mount circuit breaker for $33. I can get 2 36" 6GA battery cables with eye ends.
1 will go from the battery terminal to the circuit breaker.
The other will go out of my battery box to connect to the existing 6GA wire. The existing 30 amp fuse block can stay in place to run my other loads.
They currently have the 10GA to 6 GA connection under the TT with a huge wire nut. I will put an eye on the existing cable and connect to the new cable with a bolt, then waterproof the whole connection.
This sounds like the RIGHT and safe thing to do. Much better than the factory setup. Thank you for pointing me in the right direction.
2014 F 150 ecoboost
2008 Chrysler Aspen
09 Amerilite 21 (modified)
2013 Bendron 14' enclosed cargo
2011 4x8 open cargo

CA_Traveler
Explorer III
Explorer III
Food for thought: What works for 120VAC doesn't translate directly into 12V.

That 0.78V drop for 120VAC results in 119.22V and so who cares? But at 14.02V on a battery system something to consider... or not. :h
2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
750 Watts Solar Morningstar MPPT 60 Controller
2014 Grand Cherokee Overland

Bob

CA_Traveler
Explorer III
Explorer III
My calculator shows that 14.8V, 18', 6ga will have a 0.78V drop or 14.02V at the battery. Probably OK.

I would extend the 6A wire from the charger to the battery with a CB and tap off of that for the panel.

Actually I would upgrade to 4ga which would result in 14.3V. But I'm into performance and maybe even bragging rights.
2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
750 Watts Solar Morningstar MPPT 60 Controller
2014 Grand Cherokee Overland

Bob

time2roll
Nomad
Nomad
Really help to post some pictures of what you are looking at.

http://photoposting.is-great.net/?i=1

I get most of my electrical provisions here: https://www.genuinedealz.com/

Yes you need to upgrade the #10 wire. Also verify the grounds are #6 so the entire charging loop has the proper rating.

dockmasterdave
Explorer
Explorer
I just measured the run, it is 18'
If I want to extend the 6 GA with another piece of 6 Ga, I will probably need to replace my fuse block.
It is a simple 2 sided fuse block with 2 30 amp fuses and is wired completely with 10 Ga.
I am guessing that since one side/wire is connected to the 6 Ga run to the power center, that runs all my 12 volt in the TT.
Since the other side/wire bypasses the 6 GA run and heads back the trailer it is probably for my non fuse panel related items, IE break away braking and co/propane detector ?
I looked online but didn't see anything like the fuse "block" near my batteries. Any suggestions on where to get one ?
2014 F 150 ecoboost
2008 Chrysler Aspen
09 Amerilite 21 (modified)
2013 Bendron 14' enclosed cargo
2011 4x8 open cargo

KD4UPL
Explorer
Explorer
Generally #6 is good for 60 amps and #10 is good for 30 amps. It really all depends on what heat rating the insulation is good for and also what heat rating the terminals are rated for. Most devices probably have terminals rated for 75 degree C. Wire size is also dictated by length and thus voltage drop.
In your situation it seems like they used the #6 to reduce voltage drop due to the long run of wire. This is a normal thing to do. Just because a certain size wire will handle a certain current without overheating doesn't mean it won't lose some voltage getting to the other end.
I would extend the #6 with more #6 directly to the battery terminals, fuse it at 60 amps, and hook up your new converter. I suspect voltage drop won't be an issue but you didn't say how long the run is.

dockmasterdave
Explorer
Explorer
It just got WEIRD.
I went to take the cables off the battery to switch the converters and found the 6 GA runs the whole length of the run and in the last 3 feet, they wirenutted the 6 GA to a 3' piece of 10 GA.
My fuse block, at the battery has two 30 amp fuses and is wired in all 10 GA.
Is this 3' length of 10 GA going to mess me up ? What does that do to my reading of the ampacity chart ?
Do I calculate using the smallest GA wire in the run or doesn't that short of a 10 GA run matter ?
2014 F 150 ecoboost
2008 Chrysler Aspen
09 Amerilite 21 (modified)
2013 Bendron 14' enclosed cargo
2011 4x8 open cargo

time2roll
Nomad
Nomad
#6 is fine with 55 amps. If you pull wire I believe #4 is the max that will fit the connectors. You may also want to check if you have a fuse or breaker near the battery to verify rating. The PD will charge like a rocket when needed and consistently drop to storage voltage when expected. Make sure the jumper is in the lead-acid position, not lithium. Ampacity with 105C insulation is 100 amps for #6 but it is usually the voltage drop that becomes the size issue. Either way you are fine for now.

dockmasterdave
Explorer
Explorer
I have no idea what all the abbreviations mean on most of the ampacity charts, such as THHN THWN etc. However I did find an oversimplified one (below ) and based on this chart and others I am guessing between 65 and 75 is the amp rating. I would still like to hear from someone who knows more than I do and understands all the abbreviations etc.

[img][/img]
2014 F 150 ecoboost
2008 Chrysler Aspen
09 Amerilite 21 (modified)
2013 Bendron 14' enclosed cargo
2011 4x8 open cargo

Lwiddis
Explorer II
Explorer II
Rare will a battery bank accept 55 amps for long.
Winnebago 2101DS TT & 2022 Chevy Silverado 1500 LTZ Z71, WindyNation 300 watt solar-Lossigy 200 AH Lithium battery. Prefer boondocking, USFS, COE, BLM, NPS, TVA, state camps. Bicyclist. 14 yr. Army -11B40 then 11A - (MOS 1542 & 1560) IOBC & IOAC grad

Lwiddis
Explorer II
Explorer II
WindyNation wire size chart...

Winnebago 2101DS TT & 2022 Chevy Silverado 1500 LTZ Z71, WindyNation 300 watt solar-Lossigy 200 AH Lithium battery. Prefer boondocking, USFS, COE, BLM, NPS, TVA, state camps. Bicyclist. 14 yr. Army -11B40 then 11A - (MOS 1542 & 1560) IOBC & IOAC grad